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Choi, Vivian W., Douglas M. McCarty y R. Jude Samulski. "Host Cell DNA Repair Pathways in Adeno-Associated Viral Genome Processing". Journal of Virology 80, n.º 21 (1 de noviembre de 2006): 10346–56. http://dx.doi.org/10.1128/jvi.00841-06.
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ABSTRACT Recentstudies have shown that wild-type and recombinant adeno-associated virus (AAV and rAAV) genomes persist in human tissue predominantly as double-stranded (ds) circular episomes derived from input linear single-stranded virion DNA. Using self-complementary recombinant AAV (scAAV) vectors, we generated intermediates that directly transition to ds circular episomes. The scAAV genome ends are palindromic hairpin-structured terminal repeats, resembling a double-stranded break repair intermediate. Utilizing this substrate, we found cellular DNA recombination and repair factors to be essential for generating circular episomal products. To identify the specific cellular proteins involved, the scAAV circularization-dependent vector was used as a reporter in 19 mammalian DNA repair-deficient cell lines. The results show that RecQ helicase family members (BLM and WRN), Mre11 and NBS1 of the Mre11-Rad50-Nbs1 (MRN) complex, and ATM are required for efficient scAAV genome circularization. We further demonstrated that the scAAV genome requires ATM and DNA-PKCS, but not NBS1, to efficiently convert to a circular form in nondividing cells in vivo using transgenic mice. These studies identify specific pathways involved for further elucidating viral and cellular mechanisms of DNA maintenance important to the viral life cycle and vector utilizations.
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Watkins, Raychel, Suzanne Moshier y Aelita Pinter. "Parasites of Small Mammals in Grand Teton National Park: Babesia and Hepatozoon". UW National Parks Service Research Station Annual Reports 20 (1 de enero de 1996): 95–99. http://dx.doi.org/10.13001/uwnpsrc.1996.3295.
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Babesia microti, a parasitic protozoan, is endemic in the Microtus montanus of Grand Teton National Park. It is transmitted by the tick Ixodes eastoni and reproduces in the erythrocytes of its vole host. A second protozoan parasite, Hepatozoon sp., which is widespread in small mammals in Europe, is also found in reptiles throughout the world. The record of Hepatozoon in North American small mammals is not extensive. Hepatozoon, unlike Babesia, may be a two-host or a three-host parasite. Also unlike Babesia, for which the intermediate host is always a tick, the intermediate host of Hepatozoon may be a tick, a mite, a flea, or a mosquito. The method of transmission by the vector also differs in the two parasites. Babesia is transmitted in the tick's saliva when it bites, whereas Hepatozoon infection requires the vertebrate host to ingest a vector. In our 1996 studies, we sought more data on these two parasites. The objectives for 1996 focused on Hepatozoon: to sample specific populations of M. montanus, in which we have previously documented Hepatozoon infections; to determine whether differences exist in the infection rates at different study sites in the park; and to search for any additional vectors of Hepatozoon sp. infections in M. montanus by examining ectoparasites. These studies contributed to our long-term objectives of documenting the effects and cost of parasitism on M. montanus populations.
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Moshier, Suzanne, Raychel Watkins y Aelita Pinter. "Parasites of Small Mammals in Grand Teton National Park: Babesia and Hepatozoon". UW National Parks Service Research Station Annual Reports 19 (1 de enero de 1995): 67–72. http://dx.doi.org/10.13001/uwnpsrc.1995.3249.
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The role of parasitism, whether macro- or microparasites, and whether endo- or ectoparasites, in the demographic machinery of microtines is poorly understood. In a review of the parasites of Microtus, Timm (1985) lists no protozoan endoparasites whatsoever for this genus and observes that one of the most challenging and fruitful directions of future research with Microtus will be the statistical quantification of the cost of parasitism. Babesia microti, a parasitic protozoan, is transmitted by a tick vector and reproduces in the erythrocytes of its mammalian host. Initially, Babesia was thought to be restricted to small mammals, however, in 1970 the first human cases were diagnosed in residents of Nantucket Island, Massachusetts (Western et al. 1970). In the United States, human babesiosis is caused by B. microti. As hunians insert themselves into places where they have historically been present only occasionally, they often contract new diseases. A second protozoan parasite, Hepatozoon sp., which is widespread in small mammals in Europe, is also found in reptiles throughout the world. The record of Hepatozoon in North American small mammals is not extensive. Like Babesia, Hepatozoon is a two-host parasite. Unlike Babesia, for which the intermediate host is always a tick, the intermediate host of Hepatozoon may be a tick, a mite, a flea, or a mosquito. The method of transmission by the vector also differs in the two parasites. Babesia is transmitted in the tick's saliva when it bites, whereas Hepatozoon infection requires the vertebrate host to swallow the vector. In our 1995 studies, we sought more data on these two parasites. The objectives for 1995 were: to sample specific populations of M. montanus, in which we have previously documented Hepatozoon infections, to determine whether there were differences in the infection rates at different study sites in the park, and to search for any additional vectors of Hepatozoon sp. infections in M. montanus by examining ectoparasites. Our long-term objectives are to document the effects and cost of parasitism on M. montanus populations.
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Burattini, Marcelo N., Francisco A. B. Coutinho, Luis F. Lopez y Eduardo Massad. "Modelling the Dynamics of Leishmaniasis Considering Human, Animal Host and Vector Populations". Journal of Biological Systems 06, n.º 04 (diciembre de 1998): 337–56. http://dx.doi.org/10.1142/s0218339098000224.
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Some of the vector-borne infections with public health importance involve an animal reservoir. This work describes, through a compartimental model, the dynamics of leishmaniasis considering the interactions between the three populations involved, namely the sandfly, the domestic dog (as the principal intermediate host), and the human population. An expression for the Basic Reproduction Ratio (R0), which takes into account the time delay representing the extrinsic incubation period of the parasite in the vector, is presented. Numerical simulation, equilibrium and stability analysis provided insights into the transmission dynamics of the infection that can help in the design of control strategies.
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Svinin, Anton Olegovich, I. V. Bashinskiy, S. N. Litvinchuk, L. A. Neymark, A. Yu Ivanov, O. A. Ermakov, A. A. Vedernikov y A. Dubois. "A Mollusk Planorbarius corneus is an Intermediate Host of the Infectious Agent of Rostand’s «Anomaly P» in Green Frogs". Russian Journal of Herpetology 26, n.º 6 (15 de diciembre de 2019): 349–53. http://dx.doi.org/10.30906/1026-2296-2019-26-6-349-353.
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Here we present the first new data about the mysterious «anomaly P» of green frogs (genus Pelophylax) in about 50 years. We established that the gastropod Planorbarius corneus could be an intermediate host (or vector) of the infectious agent of the anomaly P. Symmetrical cases of polydactyly, the anomaly «cross» and heavy cases of the anomaly P, which were previously found in natural populations in the European part of Russia and recently obtained in laboratory, can be caused by this infectious agent. As the most probable cause, we assume a species of trematodes, for which the first intermediate host is P. corneus, from which they infest tadpoles of green frogs.
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Stone, Chris M., Samantha R. Schwab, Dina M. Fonseca y Nina H. Fefferman. "Human movement, cooperation and the effectiveness of coordinated vector control strategies". Journal of The Royal Society Interface 14, n.º 133 (agosto de 2017): 20170336. http://dx.doi.org/10.1098/rsif.2017.0336.
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Vector-borne disease transmission is often typified by highly focal transmission and influenced by movement of hosts and vectors across different scales. The ecological and environmental conditions (including those created by humans through vector control programmes) that result in metapopulation dynamics remain poorly understood. The development of control strategies that would most effectively limit outbreaks given such dynamics is particularly urgent given the recent epidemics of dengue, chikungunya and Zika viruses. We developed a stochastic, spatial model of vector-borne disease transmission, allowing for movement of hosts between patches. Our model is applicable to arbovirus transmission by Aedes aegypti in urban settings and was parametrized to capture Zika virus transmission in particular. Using simulations, we investigated the extent to which two aspects of vector control strategies are affected by human commuting patterns: the extent of coordination and cooperation between neighbouring communities. We find that transmission intensity is highest at intermediate levels of host movement. The extent to which coordination of control activities among neighbouring patches decreases the prevalence of infection is affected by both how frequently humans commute and the proportion of neighbouring patches that commits to vector surveillance and control activities. At high levels of host movement, patches that do not contribute to vector control may act as sources of infection in the landscape, yet have comparable levels of prevalence as patches that do cooperate. This result suggests that real cooperation among neighbours will be critical to the development of effective pro-active strategies for vector-borne disease control in today's commuter-linked communities.
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Verneau, Olivier, Sirine Melliti, Latifa Kimdil, El Hassan El Mouden, Mohamed Sghaier Achouri y Rachid Rouag. "Molecular Phylogenies of Leeches and Haemoparasites Infecting Freshwater Turtles in Aquatic Ecosystems of Northern Africa Suggest Phylogenetic Congruence between Placobdella costata Sensu Lato and Haemogregarina stepanowi Sensu Lato". Microorganisms 11, n.º 6 (15 de junio de 2023): 1584. http://dx.doi.org/10.3390/microorganisms11061584.
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Haemogregarines are blood parasites with a life-cycle involving a vertebrate as the intermediate host and an invertebrate as the definitive host and vector. Extensive phylogenetic investigations based on 18S-rRNA gene sequences have shown that Haemogregarina stepanowi (Apicomplexa: Haemogregarinidae) is able to infest a large diversity of freshwater turtle species, including the European pond turtle Emys orbicularis, the Sicilian pond turtle Emys trinacris, the Caspian turtle Mauremys caspica, the Mediterranean pond turtle Mauremys leprosa, and the Western Caspian turtle Mauremys rivulata, among others. From the same molecular markers, H. stepanowi is further considered to be a complex of cryptic species predisposed to infect the same host species. While Placobdella costata is known to be the unique vector of H. stepanowi, it is only recently that independent lineages within P. costata have been illustrated—suggesting the presence of at least five unique leech species across Western Europe. The aims of our study were therefore to investigate from mitochondrial markers (COI) the genetic diversity within haemogregarines and leeches infecting freshwater turtles of the Maghreb, in order to identify processes of parasite speciation. We showed that H. stepanowi consists of at least five cryptic species in the Maghreb, while two Placobella species were identified in the same area. Although an Eastern–Western speciation pattern was apparent for both leeches and haemogregarines, we cannot make definitive conclusions regarding co-speciation patterns between parasites and vectors. However, we cannot reject the hypothesis of a very strict host–parasite specificity within leeches.
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Portet, Anaïs, Eve Toulza, Ana Lokmer, Camille Huot, David Duval, Richard Galinier y Benjamin Gourbal. "Experimental Infection of the Biomphalaria glabrata Vector Snail by Schistosoma mansoni Parasites Drives Snail Microbiota Dysbiosis". Microorganisms 9, n.º 5 (18 de mayo de 2021): 1084. http://dx.doi.org/10.3390/microorganisms9051084.
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Host-parasite interaction can result in a strong alteration of the host-associated microbiota. This dysbiosis can affect the fitness of the host; can modify pathogen interaction and the outcome of diseases. Biomphalaria glabrata is the snail intermediate host of the trematode Schistosoma mansoni, the agent of human schistosomiasis, causing hundreds of thousands of deaths every year. Here, we present the first study of the snail bacterial microbiota in response to Schistosoma infection. We examined the interplay between B. glabrata, S. mansoni and host microbiota. Snails were infected and the microbiota composition was analysed by 16S rDNA amplicon sequencing approach. We demonstrated that the microbial composition of water did not affect the microbiota composition. Then, we characterised the Biomphalaria bacterial microbiota at the individual scale in both naive and infected snails. Sympatric and allopatric strains of parasites were used for infections and re-infections to analyse the modification or dysbiosis of snail microbiota in different host-parasite co-evolutionary contexts. Concomitantly, using RNAseq, we investigated the link between bacterial microbiota dysbiosis and snail anti-microbial peptide immune response. This work paves the way for a better understanding of snail/schistosome interaction and should have critical consequences in terms of snail control strategies for fighting schistosomiasis disease in the field.
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Velusamy, R., A. Latchumikanthan y M. K. Vijayasarathi. "The Lesser Mealworm Beetle (Alphitobius diaperinus) as an Intermediate Host for Poultry Tapeworm Raillietina cesticillus". UTTAR PRADESH JOURNAL OF ZOOLOGY 44, n.º 14 (20 de julio de 2023): 72–77. http://dx.doi.org/10.56557/upjoz/2023/v44i143560.
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Tapeworms are a widespread and recurrent problem in intensive chicken rearing and are transmitted by various types of invertebrate hosts dwelling in poultry litter. The mealworm beetle, Alphitobius diaperinus is the major pest in poultry litter and acts as an intermediate host for poultry tapeworms. Beetles collected from a poultry farm with suspected tapeworm infection were examined for the presence of the metacestode stage of the parasite. A total of 713 beetles were collected to study the vector potentiality. Out of these, 208 beetles (29.17%) were found to harbor cysticercoids of Railietina cesticillus. The percentage of cysticercoid infection in beetles was 33.42 and 24.78% respectively in two different surveys in a year. The beetles harboring the cysticercoids were identified as Alphitobius diaperinus, which may be a natural intermediate host for poultry tapeworm, Railietina cesticillus. The results of this study will help to formulate suitable control measures against the lesser mealworm beetles.
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Otahal, Alexander, Renate Fuchs, Faisal A. Al-Allaf y Dieter Blaas. "Release of Vesicular Stomatitis Virus Spike Protein G-Pseudotyped Lentivirus from the Host Cell Is Impaired upon Low-Density Lipoprotein Receptor Overexpression". Journal of Virology 89, n.º 22 (2 de septiembre de 2015): 11723–26. http://dx.doi.org/10.1128/jvi.01869-15.
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Production of a vesicular stomatitis virus spike protein G (VSVG)-pseudotyped lentiviral expression vector in HEK293 cells decreased on overexpression of low-density lipoprotein receptor (LDLR) but not that of ICAM1 or TfR1. Reverse transcription-quantitative PCR (RT-qPCR) revealed a reduction in vector RNA as a function of LDLR expression. Decreased syncytium formation suggested diminished surface expression of VSVG. Intracellular VSVG granules colocalized with LDLR, ER-Golgi intermediate compartment protein 53 (ERGIC53), LAMP2, and vimentin but not with GM130 or calnexin, suggesting that VSVG interacts with LDLR within the ERGIC, resulting in rerouting into the aggresome/autophagosome pathway.
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Kumar, Pradeep. "Potentilla fulgens: organic column purified extract and its effect on enzyme inhibition in the vector snail Lymnaea acuminata". PROCEEDINGS OF THE ZOOLOGICAL SOCIETY OF INDIA 23, n.º 01 (junio de 2024): 97. http://dx.doi.org/10.59467/pzsi.2024.23.97.
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Fasciola hepatica and F. gigantica are parasitic trematode that causes fascioliasis in cattle and humans. The vector snail Lymnaea acuminata is an intermediate host of the Fasciola species. The major preventive step against fascioliasis is the control of the host snail L. acuminata. Effect of sub-lethal concentration of (20% and 60% of 96h LC50) column purified extract of Potentilla fulgens on acid phosphatase (ACPase), alkaline phosphatase (ALPase), and acetylcholinesterase (AChE) inhibition in nervous tissue of host L. acuminata were studied. Alteration in the enzymes of ACPase, ALPase, and AChE in nervous tissue was time and concentration-dependent. Withdrawal experiment demonstrates that there was a significant recovery in ACPase, ALPase, and AChE inhibition in nervous tissues of L. acuminata were withdrawn from 7 days and treated with 20 and 60% of 96h LC50 for 96h. A significant recovery in the levels of ACPase, ALPase, and AChE was observed in the nervous tissue of L. acuminata. . KEYWORDS :Lymnaea acuminata; Potentilla fulgens; ACPase; ALPase; AChE; Fasciola
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OTRANTO, D., R. P. LIA, V. BUONO, D. TRAVERSA y A. GIANGASPERO. "Biology of Thelazia callipaeda (Spirurida, Thelaziidae) eyeworms in naturally infected definitive hosts". Parasitology 129, n.º 5 (5 de octubre de 2004): 627–33. http://dx.doi.org/10.1017/s0031182004006018.
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Thelazia callipaeda (Spirurida, Thelaziidae) eyeworm causes ocular infection in carnivores and humans in the Far East; this infection has been recently reported also in Europe – northern and southern Italy – in dogs, cats and foxes. The natural vector/s of T. callipaeda is/are unknown and the development of the nematode in its definitive hosts is limited to an experimental trial on dogs. To contribute new insights into the development of T. callipaeda in the definitive host in field conditions, eyeworms were collected from naturally infected dogs from an area with a high prevalence of infection (up to 60·14%) in the Basilicata region of southern Italy, from January 2002 to December 2003. Conjunctival secretions were also collected and examined for the presence of immature stages. The presence of blastomerized eggs throughout the period – except for the months from May to November – indicates a seasonality in the reproductive activity of T. callipaeda, coinciding with the presence/absence of the vector. In fact, 1st-stage larvae were found in the lachrymal secretions of dogs in summer (June–July 2002 and 2003), ready to be ingested by flies feeding about the eyes. The evidence of 4th-stage larvae in March 2002 and April, July and October 2003 may be accounted for by the presence of flies that act as intermediate hosts of T. callipaeda from early spring to early autumn. The presence of immature stages in October indicates an overlapping generation of nematodes and a 2nd cycle of vector infection. This basic knowledge of the development of T. callipaeda will hopefully help future epidemiological studies to identify the intermediate hosts and define the likely risk for vectors in field conditions.
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Sunita, Kumari y D. K. Singh. "Fascioliasis Control:In VivoandIn VitroPhytotherapy of Vector Snail to KillFasciolaLarva". Journal of Parasitology Research 2011 (2011): 1–7. http://dx.doi.org/10.1155/2011/240807.
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Snail is one of the important components of an aquatic ecosystem, it acts as intermediate host ofFasciolaspecies. Control of snail population below a certain threshold level is one of the important methods in the campaign to reduce the incidence of fascioliasis. Life cycle of the parasite can be interrupted by killing the snail orFasciolalarva redia and cercaria in the snail body.In vivoandin vitrotoxicity of the plant products and their active component such as citral, ferulic acid, umbelliferone, azadirachtin, and allicin against larva ofFasciolain infected snailLymnaea acuminatawere tested. Mortality of larvae were observed at 2 h, 4 h, 6 h, and 8 h, of treatment. Inin vivotreatment, azadirachtin caused highest mortality in redia and cercaria larva (8 h, LC500.11, and 0.05 mg/L) whereas inin vitrocondition allicin was highly toxic against redia and cercaria (8 h, LC500.01, and 0.009 mg/L). Toxicity of citral was lowest against redia and cercaria larva.
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Rafiq, Naseem, Sultan Ayaz, Sadaf Niaz, Sumbal Haleem, Riaz Ullah, Ahmed Bari, Mohammed Bourhia y Essam A. Ali. "Changes in the Prevalence of Natural Paramphistomum Cercariae Infection in Indoplanorbis and Lymnaea Intermediate Hosts Influenced by Meteorological Factors". Journal of Tropical Medicine 2022 (3 de febrero de 2022): 1–7. http://dx.doi.org/10.1155/2022/8719834.
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Paramphistomosis is a neglected ruminant parasitic disease caused by trematodes known as Paramphistomum, which has a diheteroxenic life cycle involving freshwater snail genera, i.e., Planorbis and Lymnaea as the intermediate host and mammals as the definitive host. Snail vector distribution, infection with Paramphistomum spp. cercariae, preferred habitat, and their relationship with certain meteorological factors were not investigated in the province Khyber Pakhtunkhwa of Pakistan. Therefore, this study is designed to evaluate the effects of meteorological factors on the occurrence and severity of Paramphistomum spp. cercariae in Indoplanorbis and Lymnaea intermediate snail hosts. For this purpose, a cross-sectional survey was conducted from October 2018 to September 2019, and snails were collected and then identified using snail shell morphology; their infection with Paramphistomum spp. cercariae was determined through microscopy; and descriptive statistics were used to estimate the prevalence of infection and evaluate their occurrence relationship with a certain meteorological factors including temperature, humidity, rainfall, and pan evaporation in different districts of the above-mentioned province of Pakistan, i.e., adjacent areas of Bara and Kabul rivers in district Nowshehra, Kabul River (Sardaryab) of district Charsadda, Kalpani River of district Mardan, and Indus River (Hund) of district Swabi. A total of 2,706 Indoplanorbis (1539) and Lymnaea (1167) snails were collected, in which overall 10.30% shed Paramphistomum spp. cercariae. The highest infection rate was found in the river of district Swabi (13.20%), while the lowest in adjacent rivers of district Nowshehra (8.19%). Meteorological factors play an essential role in the causation of Paramphistomum spp. infection, parasitic reproduction, vector growth, and survival. Due to these factors, high significant prevalence was found in the summer season (11.83), followed by autumn (11.25), which might be due to optimum temperature, relative humidity, and rainfall ( p < 0.05 ). It was concluded from the study that meteorological factors contribute to the prevalence of Paramphistomum species in the Indoplanorbis and Lymnaea, which act as vectors for the disease paramphistomosis, which may lead to the increased intensity of infection outbreaks of the parasite population in humans and domestic animals.
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Netshikweta, Rendani y Winston Garira. "A Multiscale Model for the World’s First Parasitic Disease Targeted for Eradication: Guinea Worm Disease". Computational and Mathematical Methods in Medicine 2017 (2017): 1–29. http://dx.doi.org/10.1155/2017/1473287.
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Guinea worm disease (GWD) is both a neglected tropical disease and an environmentally driven infectious disease. Environmentally driven infectious diseases remain one of the biggest health threats for human welfare in developing countries and the threat is increased by the looming danger of climate change. In this paper we present a multiscale model of GWD that integrates the within-host scale and the between-host scale. The model is used to concurrently examine the interactions between the three organisms that are implicated in natural cases of GWD transmission, the copepod vector, the human host, and the protozoan worm parasite (Dracunculus medinensis), and identify their epidemiological roles. The results of the study (through sensitivity analysis of R0) show that the most efficient elimination strategy for GWD at between-host scale is to give highest priority to copepod vector control by killing the copepods in drinking water (the intermediate host) by applying chemical treatments (e.g., temephos, an organophosphate). This strategy should be complemented by health education to ensure that greater numbers of individuals and communities adopt behavioural practices such as voluntary reporting of GWD cases, prevention of GWD patients from entering drinking water bodies, regular use of water from safe water sources, and, in the absence of such water sources, filtering or boiling water before drinking. Taking into account the fact that there is no drug or vaccine for GWD (interventions which operate at within-host scale), the results of our study show that the development of a drug that kills female worms at within-host scale would have the highest impact at this scale domain with possible population level benefits that include prevention of morbidity and prevention of transmission.
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GÜNEŞ, Nihan, Süleyman G. TÜRKSEVEN, Pınar ÖZSARI, Mustafa GÜMÜŞ y Damla BAYSAL SİVRİTEPE. "Incidence and possible sources of Tomato spotted wilt virus in tobacco grown in Denizli Province, Turkey". Notulae Botanicae Horti Agrobotanici Cluj-Napoca 50, n.º 2 (23 de mayo de 2022): 12529. http://dx.doi.org/10.15835/nbha50212529.
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Tomato spotted wilt virus (TSWV) is economically prominent disease for its impact on tobacco (Nicotiana tabacum L.) production worldwide. An increase of the incidence of symptoms typical of TSWV has been observed in tobacco production areas in Denizli province of Turkey where tobacco is significantly grown. Surveys were conducted to determine the prevalence status of TSWV in tobacco cultivars and its possible sources of infections in four tobacco growing districts of Denizli province. A total of 501 plant samples from field-grown tobaccos, weeds, potential intermediate hosts, seedlings and seeds were collected during 2019 and tested by DAS-ELISA. Of these plants, 243 belong to 55 different weed species from 26 different families with intermediate host potential. Throughout the study, 40 crop plant samples which could be intermediate hosts and 39 tobacco seed samples were also taken for testing. Adult thrips specimens were picked up from the fields and brought to the laboratory for preparations. Four vector virus species were detected when adult thrips individuals were diagnosed: Thrips tabaci Lindeman (Thysanoptera: Thripidae), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), Aeolothrips intermedius Bagnall (Thysanoptera: Aeolothripidae) and Thrips major Uzel (Thysanoptera: Thripidae). Of the 179 tobaccos sampled, 31.2% was positive; besides, of 243 weeds tested 10 were found to be infected. Echinochloa crus-galli and Tordylium apulum were determined to be new host recordings for TSWV infection. Only one tomato plant from the crop plants as intermediate hosts was infected. Cucumber mosaic virus (CMV), Alfalfa mosaic virus (AMV) and Potato virus Y (PVY) was also confirmed in tobacco fields.
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Carraretto, Davide, Laura Soresinetti, Irene Rossi, Anna R. Malacrida, Giuliano Gasperi y Ludvik M. Gomulski. "Behavioural Responses of Male Aedes albopictus to Different Volatile Chemical Compounds". Insects 13, n.º 3 (15 de marzo de 2022): 290. http://dx.doi.org/10.3390/insects13030290.
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The Asian tiger mosquito, Aedes albopictus, has become one of the most important invasive vectors for disease pathogens such as the viruses that cause chikungunya and dengue. Given the medical importance of this disease vector, a number of control programmes involving the use of the sterile insect technique (SIT) have been proposed. The identification of chemical compounds that attract males can be very useful for trapping purposes, especially for monitoring the makeup of the male population during control programmes, such as those involving the use of the SIT. Twenty-eight chemical compounds from different chemical classes were evaluated using a dual-port olfactometer assay. The compounds included known animal, fungal and plant host volatiles, and components of a putative Aedes aegypti pheromone. Many of the compounds were repellent for male mosquitoes, especially at the highest concentration. One compound, decanoic acid, acted as an attractant for males at an intermediate concentration. Decanoic acid did not elicit a significant response from female mosquitoes.
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Mohammadian, Omid, Masoumeh Rajabibazl, Hadi Bayat y Azam Rahimpour. "Transient Expression of a Recombinant Monoclonal Antibody in HEK293T Cells". Pharmaceutical Sciences 24, n.º 3 (23 de septiembre de 2018): 207–12. http://dx.doi.org/10.15171/ps.2018.30.
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Background: Monoclonal antibodies (mAbs) are considered the most important and financially successful category of the biopharmaceuticals. Extensive optimization of the expression vector, host system and culture parameters are required for the successful production of active monoclonal antibodies in mammalian cells. In this regards, transient expression enables rapid and cost-effective production of recombinant proteins for initial characterization. Methods: In the present study, an internal ribosome entry site (IRES) based bicistronic expression system has been evaluated for the transient expression of an anti-CD52 monoclonal antibody in mammalian cells. The IRES based bicistronic vector was generated through sequential cloning of the Light chain (LC), IRES, and Heavy chain (HC) in an intermediate vector and transfer of the resulting fragment to the expression vector. Transfection of the HEK293T cells was performed and antibody expression was analyzed in cell culture supernatant. Results: Restriction enzyme analysis indicated successful cloning of the antibody coding unit in the expression vector. Analysis of EGFP expression indicated successful transfection of the HEK293T cells. Production levels of 220 µg/L of antibody were achieved in HEK293T cells during three days of culture. Conclusion: Our results show the convenience and efficiency of the bicistronic expression system for transient expression of the whole monoclonal antibodies in mammalian cells.
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Ahmad, Alzahraa Abdelraouf, Haidi Karam-Allah Ramadan, Waleed Attia Hassan, Mohammed Ageeli Hakami, Enas Abdelhameed Mahmoud Huseein, Sara Abdel-Aal Mohamed, Adnan Ahmed Mohamed y Nahed Ahmed Elossily. "New perspectives for fascioliasis in Upper Egypt’s new endemic region: Sociodemographic characteristics and phylogenetic analysis of Fasciola in humans, animals, and lymnaeid vectors". PLOS Neglected Tropical Diseases 16, n.º 12 (28 de diciembre de 2022): e0011000. http://dx.doi.org/10.1371/journal.pntd.0011000.
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Background Fascioliasis is a significant vector-borne disease that has emerged in numerous tropical and subtropical countries causing severe health problems. Egypt is one of the fascioliasis endemic regions; however, the current situation in Upper Egypt is understudied, with only sporadic human cases or outbreaks. This study aims to highlight the sociodemographic characteristics of human fascioliasis in a newly emerged endemic area in Upper Egypt, along with risk factors analysis and the molecular characteristics of the fasciolid population in humans, animals, and lymnaeid snails. Methodology/Principal findings The study reported Fasciola infection in patients and their close relatives by analyzing the risk of human infection. Morphological and molecular characterization was performed on lymnaeid snails. Multigene sequencing was also used to characterize fasciolids from human cases, cattle, and pooled snail samples. The study identified asymptomatic Fasciola infection among family members and identified the presence of peridomestic animals as a significant risk factor for infection. This is the first genetic evidence that Radix auricularia exists as the snail intermediate host in Egypt. Conclusions/Significance This study revealed that Assiut Governorate in Upper Egypt is a high-risk area for human fascioliasis that requires additional control measures. Fasciola hepatica was the main causative agent infecting humans and snail vectors in this newly emerged endemic area. In addition, this is the first report of R. auricularia as the snail intermediate host transmitting fascioliasis in Upper Egypt. Further research is required to clarify the widespread distribution of Fasciola in Egypt’s various animal hosts. This provides insight into the mode of transmission, epidemiological criteria, and genetic diversity of fasciolid populations in Upper Egypt.\
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Serkova. "FACTORS AFFECTING THE DEVELOPMENT OF DIROFILARIASIS PATHOGENS IN INTERMEDIATE HOSTS, BLOOD-SUCKING MOSQUITOES (REVIEW)". THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL, n.º 23 (18 de abril de 2022): 417–21. http://dx.doi.org/10.31016/978-5-6046256-9-9.2022.23.417-421.
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Dirofilariasis is a transmissible parasitic disease caused by helminths Dirofilaria repens and D. immitis. Vectors of pathogens are blood-sucking mosquitoes (Diptera, Culicidae). Climate change, urbanization, and importation of exotic mosquito species into the territory of Russia lead to the expansion of the Dirofilaria vector range and, consequently, an increase in the incidence of the disease among the population and animals. The purpose of this research was to study the literature data on factors of the dirofilariasis pathogen development in blood-sucking mosquitoes. An important factor in the development of Dirofilaria from the larval stage to the invasive stage is an optimal environmental temperature, the average daily value of which should not be less than 130. This number is referred to as the "Dirofilaria Development Unit (DDU)". The immune response of the insect plays an important role in the helminth development in the intermediate host. Melanin, which is produced by mosquito hemocytes, forms a capsule around the larvae thus preventing their maturation. However, the extent of this response depends on the phenoloxidase enzyme and the age of the mosquito. The symbiotic intracellular Wolbachia bacteria found in Dirofilaria are essential for the helminth development in mosquitoes. But no information has currently been found on interaction between mosquito immunity and these bacteria in the literature; although a correlation has been found between the mosquito infected with the bacteria and the probability of infection transmitted by them.
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Acosta-Leal, Rodolfo, Becky K. Bryan y Charles M. Rush. "Host Effect on the Genetic Diversification of Beet necrotic yellow vein virus Single-Plant Populations". Phytopathology® 100, n.º 11 (noviembre de 2010): 1204–12. http://dx.doi.org/10.1094/phyto-04-10-0103.
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Theoretical models predict that, under restrictive host conditions, virus populations will exhibit greater genetic variability. This virus response has been experimentally demonstrated in a few cases but its relation with a virus's capability to overcome plant resistance is unknown. To explore the genetic host effects on Beet necrotic yellow vein virus (BNYVV) populations that might be related to resistance durability, a wild-type virus isolate was vector inoculated into partially resistant Rz1, Rz2, and susceptible sugar beet cultivars during a serial planting experiment. Cloning and sequencing a region of the viral RNA-3, involving the pathogenic determinant p25, revealed that virus diversity significantly increased in direct proportion to the strength of host resistance. Thus, whereas virus titers were highest, intermediate, and lowest in susceptible, Rz1, and Rz2 plants, respectively; the average number of nucleotide differences among single-plant populations was 0.8 (±0.1) in susceptible, 1.4 (±0.1) in Rz1, and 2.4 (±0.2) in Rz2 genotypes. A similar relationship between host restriction to BNYVV root accumulation and virus genetic variability was detected in fields of sugar beet where these specific Rz1- and Rz2-mediated resistances have been defeated.
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HAGEN, H. E. y S. L. KLÄGER. "Integrin-like RGD-dependent cell adhesion mechanism is involved in the rapid killing of Onchocerca microfilariae during early infection of Simulium damnosum s.l." Parasitology 122, n.º 4 (abril de 2001): 433–38. http://dx.doi.org/10.1017/s0031182001007545.
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Injection trials with compatible and non-compatible Onchocerca species into S. damnosum s.l., the vector of human and bovine onchocerciasis, demonstrated that the rapid killing of microfilariae within the blackfly's haemocoel is species specific. In the presence of the peptide RGDS as a blocking agent for integrin-like receptors of haemocytes, the survival of O. ochengi microfilariae in its natural intermediate host was significantly increased. This increased survival 24 h p.i. correlated with a significant decrease of apoptosis levels in the microfilariae following a 2 h exposure to the haemolymph in vivo. These findings suggest that haemocytes are directly involved in the killing of Onchocerca microfilariae in the blackfly.
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Perkins, Susan. "Parasites are Particularly Problematic". Biodiversity Information Science and Standards 2 (5 de julio de 2018): e25604. http://dx.doi.org/10.3897/biss.2.25604.
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Although they are hyperdiverse and intensively studied, parasites present major challenges when it comes to phylogenetics, taxonomy, and biodiversity informatics. The collection of any parasitic organism entails the linking of at least two specimens - the parasite and the host. If the parasite has a complex life cycle, then this becomes further complicated by requiring the linking of three or more hosts, such as the parasite, its intermediate host (vector) and its definitive host(s). Parasites are sometimes collected as byproduct of another collection event and are not studied immediately - which has the potential to disconnect them further in terms of information content and continuity- and the converse if also common - parasites can be collected by parasitologists, who do not necessarily take host vouchers or incorporate host taxonomy, let alone other metadata for these events. Using the specific example of the malaria parasites (Order Haemosporida) I will present examples of the specific challenges that have accompanied the study of these parasites including issues of delimiting species, phylogenetic study, including genetic oddities that are unique to these organisms, and taxonomic quandries that we now find ourselves in, along with other problems with maintaining continuity of information in a group that is both diverse biologically and important medically.
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Berkower, Ira, Konstantin Virnik, Yisheng Ni, Kirk Prutzman y Angelo Spadaccini. "Stable expression of a foreign protein by a live rubella viral vector (45.25)". Journal of Immunology 184, n.º 1_Supplement (1 de abril de 2010): 45.25. http://dx.doi.org/10.4049/jimmunol.184.supp.45.25.
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Abstract Live attenuated rubella virus has a number of desirable features for a live viral vector. It has a good safety profile, so it can immunize while growing exponentially in the host. It immunizes at a low dose, and one dose protects (against rubella) for life. It grows well in rhesus macaques, which allow a viral challenge. It has no DNA intermediate, cannot integrate, and usually does not persist in the host. A full length infectious cDNA clone of rubella was available for modification, but prior efforts to express foreign genes were frustrated by genetic instability and size limitations on the insert. A deletion of 507 bp in nonstructural gene P150 was permissive, so we asked whether this deletion could make room for insertion of zoanthus GFP (792 bp). By using the deletion/insertion strategy, zGFP was stably expressed for at least 12 passages. In the zGFP hybrid, rubella structural proteins were expressed at normal levels, while the vector grew to high titer (4 X 10^6/ml). Normal P150 function was detected by P150-GFP labeling of functional replication centers in living cells. Rubella may be useful for expressing vaccine antigens as large as most viral proteins, and it is stable enough for vaccine production followed by growth in vivo. This approach may extend the range and utility of rubella to include immunization against other viruses for which attenuation is not currently feasible.
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Moshier, Suzanne, William O'Dell, Raychel Watkins y Aelita Pinter. "Parasites of Small Mammals in Grand Teton National Park: Babesia and Hepatozoon". UW National Parks Service Research Station Annual Reports 18 (1 de enero de 1994): 65–75. http://dx.doi.org/10.13001/uwnpsrc.1994.3197.
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In a review of the parasites of Microtus, Timm (1985) lists no protozoan endoparasites whatsoever for this genus. The role of parasitism, whether macro- or microparasites, and whether endo- or ectoparasites, in the demographic machinery of microtines is poorly understood. Timm (1985) astutely observes that one of the most challenging and fruitful directions of future research with Microtus will be the statistical quantification of the cost of parasitism. In addition, since humans in the Grand Teton National Park may encounter protozoon parasites that are potentially pathogenic to humans, it is useful to characterize the occurrence and biology of such organisms in the parko Babesia microti, a parasitic protozoon, is transmitted by a tick vector and reproduces in the erythrocytes of its mammalian host. Initially, Babesia was thought to be restricted to small mammals; however, in 1970 the first human cases were diagnosed in residents of Nantucket Island, Massachusetts (Western et al, 1970). Over 200 cases of human babesiosis have been documented worldwide. In the United States, human babesiosis is caused by B. microti. Most of these cases have occurred in the eastern United States. The earliest report of an organism that fits the description of Babesia in human erythrocytes is that of Wilson et al. (1904), who found an unknown organism in human erythrocytes while investigating the cause of Rocky Mountain Spotted fever. Documented cases of babesiosis in many areas of the United States are increasing (Steketee et al, 1985). As humans insert themselves into places where they have historically been present only occasionally, they often contract new diseases. A second protozoon parasite, Hepatozoon sp., which is widespread in small mammals in Europe, is also found in reptiles throughout the world. The record of Hepatozoon in North American small mammals is not extensive. Fewer than 10 species of mammals have been shown to harbor Hepatozoon parasites. Like Babesia, Hepatozoon is a two-host parasite. Unlike Babesia, for which the intermediate host is always a tick, the intermediate host in the Hepatozoon may be a tick, a mite, a flea, or a mosquito. The method of transmission by the vector also differs in the two parasites. Babesia is transmitted in saliva when the tick bites, whereas Hepatozoon infection requires the vertebrate host to swallow the vector. In our 1994 studies, we sought to extend knowledge of these two parasites. The specific objectives for 1994 were: to sample specific populations of M. molltanus, in which we have previously documented Hepatozoon infections, to determine whether there are differences in the infection rates at different study sites in the park; to search for the vector of Hepatozoon sp. infections in M. montanus by examining ectoparasites; to collect and rear ticks from M. montanus for use in R microti transmission studies; and to complete a comparison of the spleen histology of babesiosis in infected and uninfected laboratory animals, with inclusion of data from wild animals, as available. Our long-term objectives are to document the effects and cost of parasitism on vole populations and to determine the potential of small mammals of Grand Teton National Park to serve as reservoirs of human parasites.
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Nguyen, Karena H., Philipp H. Boersch-Supan, Rachel B. Hartman, Sandra Y. Mendiola, Valerie J. Harwood, David J. Civitello y Jason R. Rohr. "Interventions can shift the thermal optimum for parasitic disease transmission". Proceedings of the National Academy of Sciences 118, n.º 11 (8 de marzo de 2021): e2017537118. http://dx.doi.org/10.1073/pnas.2017537118.
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Temperature constrains the transmission of many pathogens. Interventions that target temperature-sensitive life stages, such as vector control measures that kill intermediate hosts, could shift the thermal optimum of transmission, thereby altering seasonal disease dynamics and rendering interventions less effective at certain times of the year and with global climate change. To test these hypotheses, we integrated an epidemiological model of schistosomiasis with empirically determined temperature-dependent traits of the human parasite Schistosoma mansoni and its intermediate snail host (Biomphalaria spp.). We show that transmission risk peaks at 21.7 °C (Topt), and simulated interventions targeting snails and free-living parasite larvae increased Topt by up to 1.3 °C because intervention-related mortality overrode thermal constraints on transmission. This Topt shift suggests that snail control is more effective at lower temperatures, and global climate change will increase schistosomiasis risk in regions that move closer to Topt. Considering regional transmission phenologies and timing of interventions when local conditions approach Topt will maximize human health outcomes.
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Hansen, Bjarne G., Bo Salomonsen, Morten T. Nielsen, Jakob B. Nielsen, Niels B. Hansen, Kristian F. Nielsen, Torsten B. Regueira, Jens Nielsen, Kiran R. Patil y Uffe H. Mortensen. "Versatile Enzyme Expression and Characterization System for Aspergillus nidulans, with the Penicillium brevicompactum Polyketide Synthase Gene from the Mycophenolic Acid Gene Cluster as a Test Case". Applied and Environmental Microbiology 77, n.º 9 (11 de marzo de 2011): 3044–51. http://dx.doi.org/10.1128/aem.01768-10.
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ABSTRACTAssigning functions to newly discovered genes constitutes one of the major challenges en route to fully exploiting the data becoming available from the genome sequencing initiatives. Heterologous expression in an appropriate host is central in functional genomics studies. In this context, filamentous fungi offer many advantages over bacterial and yeast systems. To facilitate the use of filamentous fungi in functional genomics, we present a versatile cloning system that allows a gene of interest to be expressed from a defined genomic location ofAspergillus nidulans. By a single USER cloning step, genes are easily inserted into a combined targeting-expression cassette ready for rapid integration and analysis. The system comprises a vector set that allows genes to be expressed either from the constitutive PgpdA promoter or from the inducible PalcA promoter. Moreover, by using the vector set, protein variants can easily be made and expressed from the same locus, which is mandatory for proper comparative analyses. Lastly, all individual elements of the vectors can easily be substituted for other similar elements, ensuring the flexibility of the system. We have demonstrated the potential of the system by transferring the 7,745-bp largempaCgene fromPenicillium brevicompactumtoA. nidulans. In parallel, we produced defined mutant derivatives ofmpaC, and the combined analysis ofA. nidulansstrains expressingmpaCor mutatedmpaCgenes unequivocally demonstrated thatmpaCindeed encodes a polyketide synthase that produces the first intermediate in the production of the medically important immunosuppressant mycophenolic acid.
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Tomasina, Ramiro, Fabiana C. González, Andrés Cabrera, Yester Basmadjián y Carlos Robello. "From Trypomastigotes to Trypomastigotes: Analyzing the One-Way Intracellular Journey of Trypanosoma cruzi by Ultrastructure Expansion Microscopy". Pathogens 13, n.º 10 (2 de octubre de 2024): 866. http://dx.doi.org/10.3390/pathogens13100866.
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The protozoan parasite Trypanosoma cruzi is the causative agent of Chagas disease, also called American trypanosomiasis. This neglected tropical disease affects millions of individuals across the Americas. To complete its life cycle, T. cruzi parasitizes both vertebrate hosts and its vector, commonly known as the ‘kissing bug’. The parasite’s survival and proliferation strategies are driven by the diverse environments it encounters. Despite being described by Carlos Chagas in 1909, significant knowledge gaps persist regarding the parasite’s various life forms and adaptive capabilities in response to environmental cues. In this study, we employed Ultrastructure Expansion Microscopy to explore the intricate journey of T. cruzi within the host cell. Upon entry into the host cell, trypomastigotes undergo folding, resulting in intermediate forms characterized by a rounded cell body, anterior positioning of basal bodies, and a shortened flagellum. The repositioning of basal bodies and the kinetoplast and the shortening of the flagella mark the culmination of intracellular amastigogenesis. Furthermore, we analyzed intracellular trypomastigogenesis, identifying discrete intermediate forms, including leaf-shaped stages and epimastigote-like forms, which suggests a complex differentiation process. Notably, we did not observe any dividing intracellular epimastigotes, indicating that these may be non-replicative forms within the host cell. Our detailed examination of amastigote cell division revealed semi-closed nuclear mitosis, with mitotic spindle formation independent of basal bodies. This study provides new insights into the morphological and cytoskeletal changes during the intracellular stages of T. cruzi, providing a model for understanding the dynamics of intracellular amastigogenesis and trypomastigogenesis.
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Agrahari, Pooja. "Attraction of Umbelliferone in Snail Attractant Pellets (SAP) against the Snail Lymnaea acuminata: An Intermediate Host of Fasciola gigantica". Asian Journal of Research in Zoology 6, n.º 2 (24 de abril de 2023): 33–39. http://dx.doi.org/10.9734/ajriz/2023/v6i2110.
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Snail control method is one of the best ways to management of the fasciolosis. Snail attractant pellets (bait) containing attractant and molluscicide is the good alternative method for control of the Lymnaea acuminata, which is a known intermediate host of Fasciola gigantica. The result of the present study is to find the attraction of molluscicide umbelliferone in snail attractant pellets (SAP) against the Lymnaea acuminata, a vector of snail in different months of the year. Data shows that active molluscicidal component (umbelliferone) showed more attraction at lower concentration. On the contrary, at higher concentration, attraction of snail decreases significantly throughout the year. The attraction of snails declined significantly (P < 0.01) as the concentrations of molluscicide incorporated inside the pellets were increased and water temperature is low (i.e., in winter season). SAP containing 0.5% umbelliferone + starch attract maximum snails (46.0%) and 0.5% umbelliferone + proline, attract maximum snails (42.33%), in the month of June, whereas minimum attraction was observed in the month of January to March when SAP containing 7.0% umbelliferone + starch (6.23-8.1%) and when SAP containing 3.0 % umbelliferone + proline (7.33-9.45%).
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Otranto, D., C. Cantacessi, G. Testini y R. P. Lia. "Phortica variegata as an intermediate host of Thelazia callipaeda under natural conditions: Evidence for pathogen transmission by a male arthropod vector". International Journal for Parasitology 36, n.º 10-11 (septiembre de 2006): 1167–73. http://dx.doi.org/10.1016/j.ijpara.2006.06.006.
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Johnson, Pieter T. J., Peder J. Lund, Richard B. Hartson y Timothy P. Yoshino. "Community diversity reduces Schistosoma mansoni transmission, host pathology and human infection risk". Proceedings of the Royal Society B: Biological Sciences 276, n.º 1662 (20 de enero de 2009): 1657–63. http://dx.doi.org/10.1098/rspb.2008.1718.
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Global biodiversity loss and disease emergence are two of the most challenging issues confronting science and society. Recently, observed linkages between species-loss and vector-borne infections suggest that biodiversity may help reduce pathogenic infections in humans and wildlife, but the mechanisms underlying this relationship and its applicability to a broader range of pathogens have remained speculative. Here, we experimentally evaluated the effects of host community structure on transmission of the human pathogen, Schistosoma mansoni , which alternates between snail intermediate hosts and vertebrate definitive hosts. By manipulating parasite exposure and community diversity, we show that heterospecific communities cause a 25–50 per cent reduction in infection among snail hosts ( Biomphalaria glabrata ). Infected snails raised alongside non-host snails ( Lymnaea or Helisoma sp.) also produced 60–80 per cent fewer cercariae, suggesting that diverse communities could reduce human infection risk. Because focal host density was held constant during experiments, decreases in transmission resulted entirely from diversity-mediated pathways. Finally, the decrease in infection in mixed-species communities led to an increase in reproductive output by hosts, representing a novel example of parasite-mediated facilitation. Our results underscore the significance of community structure on transmission of complex life-cycle pathogens, and we emphasize enhanced integration between ecological and parasitological research on the diversity–disease relationship.
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Martins, H., T. Nunes y Fernando Boinas. "Modélisation de la survenue des vecteurs de la fièvre catarrhale ovine à l'aide des systèmes d'information géographiques et de la télédétection". Revue d’élevage et de médecine vétérinaire des pays tropicaux 62, n.º 2-4 (1 de febrero de 2009): 154. http://dx.doi.org/10.19182/remvt.10062.
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Bluetongue (BT) is an infectious non-contagious disease which mainly affects domestic ruminants. It is caused by an arbovirus (BTV) from the family Reoviridae and its transmission is commonly associated with an intermediate arthropod host from the genus Culicoides. Culicoides imicola is the main vector of BTV in the Mediterranean Basin. Entomological surveillance programmes make it possible to collect continuously data of vital importance for the spatial and temporal investigation of BT vector distribution. In May 2005, Portugal has implemented this programme, which is providing a considerable amount of data concerning the abundance, and spatial and temporal distribution of several Culicoides species. Remote sensing is the process of acquiring data about a geographical object through several aircrafts or satellites built-in sensors and thus allowing the collection of useful information to characterize biophysical, climatic and environmental variables. Some of these variables influence survival, development and dispersion of BT vectors. The combination of satellite imagery and entomological surveillance data using geographical information systems (GIS) helps to develop models for the prediction of spatial occurrence of disease vectors. These models might be useful to identify risk areas for disease transmission and are therefore important for the development of targeted sanitary control measures. Two mathematical approaches were selected to model the spatial occurrence of Culicoides imicola, i.e. discriminant analysis and logistic regression. Climatic, remotely sensed and national entomological data were used to build both models. Statistical packages and GIS were then used to implement these models. The discriminant analysis model was less accurate, presenting a sensitivity of 76.6% and a specificity of 75.3%. The logistic regression model was more robust and presented 80.9% sensitivity and 83.6% specificity. Descriptive spatial statistics were then calculated to characterize the landscape features associated with the presence/absence of BT vectors.
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Au, Ming Fung Franco, Gray A. Williams y Jerome H. L. Hui. "Status Quo and Future Perspectives of Molecular and Genomic Studies on the Genus Biomphalaria—The Intermediate Snail Host of Schistosoma mansoni". International Journal of Molecular Sciences 24, n.º 5 (3 de marzo de 2023): 4895. http://dx.doi.org/10.3390/ijms24054895.
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Schistosomiasis, or also generally known as bilharzia or snail fever, is a parasitic disease that is caused by trematode flatworms of the genus Schistosoma. It is considered by the World Health Organisation as the second most prevalent parasitic disease after malaria and affects more than 230 million people in over 70 countries. People are infected via a variety of activities ranging from agricultural, domestic, occupational to recreational activities, where the freshwater snails Biomphalaria release Schistosoma cercariae larvae that penetrate the skin of humans when exposed in water. Understanding the biology of the intermediate host snail Biomphalaria is thus important to reveal the potential spread of schistosomiasis. In this article, we present an overview of the latest molecular studies focused on the snail Biomphalaria, including its ecology, evolution, and immune response; and propose using genomics as a foundation to further understand and control this disease vector and thus the transmission of schistosomiasis.
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Thompson, S. N., R. W. K. Lee, V. Mejia-Scales y M. Shams El-Din. "Biochemical and morphological pathology of the foot of the schistosome vector Biomphalaria glabrata infected with Schistosoma mansoni". Parasitology 107, n.º 3 (septiembre de 1993): 275–85. http://dx.doi.org/10.1017/s0031182000079257.
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SummaryInfection by Schistosoma mansoni resulted in morphological and biochemical changes to the foot of its intermediate host, Biomphalaria glabrata. Migration through, and emergence of cercariae from, the foot was observed and evidenced by lesions on the ciliated foot surface. This was accompanied by a significant decrease in the velocity of movement by infected individuals. In vivo31P NMR spectral analyses demonstrated that the foot of infected snails had a lower phosphoarginine (PA)/adenosine 5' triphosphate (ATP) ratio than that of uninfected controls. Moreover, kinetic experiments, employing saturation transfer, demonstrated the pseudo-first-order rate constant for the arginine kinase-catalysed exchange reaction in the forward direction, that is, PA→ATP was decreased by infection. The reverse reaction was not observed by the NMR methods used. PA was depleted upon exposure to hypoxic conditions suggesting its traditional role in preserving ATP level. Partly oxidized metabolic end-products were not observed in snails maintained under aerobic conditions, but succinate, propionate, acetate and lactate rapidly accumulated under hypoxic conditions.
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Wang, Lingjun, Di Li, Changzhu Yin, Hongri Tang, Bo Luo, Rong Yan, Yujuan Shen y Hui Liu. "Laboratory Culture and Life Cycle of Thelazia callipaeda in Intermediate and Definitive Hosts". Pathogens 11, n.º 9 (19 de septiembre de 2022): 1066. http://dx.doi.org/10.3390/pathogens11091066.
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Human thelaziasis caused by Thelazia callipaeda is being increasingly reported worldwide. Notably, an epidemic trend is observed in Southwest China. Whether Phortica okadai found in Southwest China can act as a vector of T. callipaeda and human-derived T. callipaeda animal infections has not been widely reported. Here, P. okadai was maintained in a laboratory and experimentally infected with first-stage larvae collected from adult T. callipaeda that were isolated from infected human subjects. Dead P. okadai were subjected to PCR assay and dissected every two days to detect T. callipaeda. Subsequently, live flies were used to infect a rabbit. The infection procedures were performed once a day (20 min) for two weeks. The results show that L1 collected from the adult T. callipaeda could successfully parasitize P. okadai captured in Zunyi, a city in Southwest China, and developed into L3, and a rabbit was successfully infected with T. callipaeda using P. okadai as the intermediate host. The present study demonstrates a human-derived T. callipaeda infection in rabbits, through P. okadai, under laboratory conditions for the first time. These results provide insights into the transmission cycle of T. callipaeda and constitute a foundation to develop an effective treatment protocol for T. callipaeda infection.
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Moskvin. "SCHISTOSOMA TURKESTANICA SKRJABIN, 1913: TOPOGRAPHY OF CERCARIAE EMISSION FROM A SPONTANEOUSLY INVADED OBLIGATE INTERMEDIATE HOST LYMNAEA AURICULARIA L., 1758". THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL, n.º 23 (18 de abril de 2022): 327–32. http://dx.doi.org/10.31016/978-5-6046256-9-9.2022.23.327-332.
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The algorithm of ethology of cercariae (=furcocercariae) of the trematode Schistosoma turkestanica Skrjabin, 1913, when implementing the scenario of the emission process from the naturally invaded mollusk Lymnaea auricularia L., 1758, is constant and consists of two periods. In the first, preliminary, larvae migrate into the subepithelial tissue of the mollusk. In the second, final, consisting of two phases, furcocercariae pierce the epithelial tissue "from the inside out" and go out into the external environment. Initiation by cercariae of the process of exit from the body of the mollusk Lymnaea auricularia L., 1758, excludes the possibility of suspension or reverse development of the sequence of events. Anatomical and topographic areas of the body of the obligate intermediate host Lymnaea auricularia L., 1758, are not limiting factors for the realization of the final phases of the emission process of the cercariae of the trematode Schistosoma turkestanica Skrjabin, 1913. The resulting vector of interstitial migration of cercariae, stochastically oriented in the direction of the shell mouth of the mollusk Lymnaea auricularia L., 1758, brings the larva into the subepithelial tissue in any topographic area of the body of the intermediate host, where the integumentary epithelium borders with the external environment. To denote the anatomical topography of the apical part of the body of the cercarium trematode Schistosoma turkestanica Skrjabin, 1913, we propose to use the term "apical talus organ". The process of emission of cercariae of the trematode Schistosoma turkestanica Skrjabin, 1913, from the body of the mollusk Lymnaea auricularia L., 1758, is invasive for the latter.
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Daniel, René, James G. Greger, Richard A. Katz, Konstantin D. Taganov, Xiaoyun Wu, John C. Kappes y Anna Marie Skalka. "Evidence that Stable Retroviral Transduction and Cell Survival following DNA Integration Depend on Components of the Nonhomologous End Joining Repair Pathway". Journal of Virology 78, n.º 16 (15 de agosto de 2004): 8573–81. http://dx.doi.org/10.1128/jvi.78.16.8573-8581.2004.
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ABSTRACT We have previously reported several lines of evidence that support a role for cellular DNA repair systems in completion of the retroviral DNA integration process. Failure to repair an intermediate in the process of integrating viral DNA into host DNA appears to trigger growth arrest or death of a large percentage of infected cells. Cellular proteins involved in the nonhomologous end joining (NHEJ) pathway (DNA-PKCS) and the damage-signaling kinases (ATM and ATR) have been implicated in this process. However, some studies have suggested that NHEJ proteins may not be required for the completion of lentiviral DNA integration. Here we provide additional evidence that NHEJ proteins are required for stable transduction by human immunodeficiency type 1 (HIV-1)-based vectors. Our analyses with two different reporters show that the number of stably transduced DNA-PKCS-deficient scid fibroblasts was reduced by 80 to 90% compared to the number of control cells. Furthermore, transduction efficiency can be restored to wild-type levels in scid cells that are complemented with a functional DNA-PKCS gene. The efficiency of stable transduction by an HIV-1-based vector is also reduced upon infection of Xrcc4 and ligase IV-deficient cells, implying a role for these components of the NHEJ repair pathway. Finally, we show that cells deficient in ligase IV are killed by infection with an integrase-competent but not an integrase-deficient HIV-1 vector. Results presented in this study lend further support to a general role for the NHEJ DNA repair pathway in completion of the retroviral DNA integration process.
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Lado, Sara, Jan Futas, Martin Plasil, Tom Loney, Pia Weidinger, Jeremy V. Camp, Jolanta Kolodziejek et al. "Crimean–Congo Hemorrhagic Fever Virus Past Infections Are Associated with Two Innate Immune Response Candidate Genes in Dromedaries". Cells 11, n.º 1 (21 de diciembre de 2021): 8. http://dx.doi.org/10.3390/cells11010008.
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Dromedaries are an important livestock, used as beasts of burden and for meat and milk production. However, they can act as an intermediate source or vector for transmitting zoonotic viruses to humans, such as the Middle East respiratory syndrome coronavirus (MERS-CoV) or Crimean–Congo hemorrhagic fever virus (CCHFV). After several outbreaks of CCHFV in the Arabian Peninsula, recent studies have demonstrated that CCHFV is endemic in dromedaries and camel ticks in the United Arab Emirates (UAE). There is no apparent disease in dromedaries after the bite of infected ticks; in contrast, fever, myalgia, lymphadenopathy, and petechial hemorrhaging are common symptoms in humans, with a case fatality ratio of up to 40%. We used the in-solution hybridization capture of 100 annotated immune genes to genotype 121 dromedaries from the UAE tested for seropositivity to CCHFV. Through univariate linear regression analysis, we identified two candidate genes belonging to the innate immune system: FCAR and CLEC2B. These genes have important functions in the host defense against viral infections and in stimulating natural killer cells, respectively. This study opens doors for future research into immune defense mechanisms in an enzootic host against an important zoonotic disease.
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Ribeiro, Karlos A. L., Cenira Monteiro de Carvalho, Maria Teresa Molina, Estelita Pereira Lima, Eulogio López-Montero, José Rui M. Reys, Maria Beatriz Farias de Oliveira, Antonio Ventura Pinto, Antônio Euzébio G. Santana y Marília O. F. Goulart. "Activities of naphthoquinones against Aedes aegypti (Linnaeus, 1762) (Diptera: Culicidae), vector of dengue and Biomphalaria glabrata (Say, 1818), intermediate host of Schistosoma mansoni". Acta Tropica 111, n.º 1 (julio de 2009): 44–50. http://dx.doi.org/10.1016/j.actatropica.2009.02.008.
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Zhang, Zhichao, Xiaojuan Guo, Wenzhe Hou, Xiaohui Zou, Yongjin Wang, Shuqing Liu y Zhuozhuang Lu. "User-Friendly Replication-Competent MAdV-1 Vector System with a Cloning Capacity of 3.3 Kilobases". Viruses 16, n.º 5 (11 de mayo de 2024): 761. http://dx.doi.org/10.3390/v16050761.
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Mouse adenoviruses (MAdV) play important roles in studying host–adenovirus interaction. However, easy-to-use reverse genetics systems are still lacking for MAdV. An infectious plasmid pKRMAV1 was constructed by ligating genomic DNA of wild-type MAdV-1 with a PCR product containing a plasmid backbone through Gibson assembly. A fragment was excised from pKRMAV1 by restriction digestion and used to generate intermediate plasmid pKMAV1-ER, which contained E3, fiber, E4, and E1 regions of MAdV-1. CMV promoter-controlled GFP expression cassette was inserted downstream of the pIX gene in pKMAV1-ER and then transferred to pKRMAV1 to generate adenoviral plasmid pKMAV1-IXCG. Replacement of transgene could be conveniently carried out between dual BstZ17I sites in pKMAV1-IXCG by restriction-assembly, and a series of adenoviral plasmids were generated. Recombinant viruses were rescued after transfecting linearized adenoviral plasmids to mouse NIH/3T3 cells. MAdV-1 viruses carrying GFP or firefly luciferase genes were characterized in gene transduction, plaque-forming, and replication in vitro or in vivo by observing the expression of reporter genes. The results indicated that replication-competent vectors presented relevant properties of wild-type MAdV-1 very well. By constructing viruses bearing exogenous fragments with increasing size, it was found that MAdV-1 could tolerate an insertion up to 3.3 kb. Collectively, a replication-competent MAdV-1 vector system was established, which simplified procedures for the change of transgene or modification of E1, fiber, E3, or E4 genes.
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Zhu, Xuechen, Rongbin Wang, Vilja Siitonen, Nemanja Vuksanovic, Nicholas R. Silvaggi, Charles E. Melançon III y Mikko Metsä-Ketelä. "ActVI-ORFA directs metabolic flux towards actinorhodin by preventing intermediate degradation". PLOS ONE 19, n.º 8 (9 de agosto de 2024): e0308684. http://dx.doi.org/10.1371/journal.pone.0308684.
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The biosynthetic pathway of actinorhodin in Streptomyces coelicolor A3(2) has been studied for decades as a model system of type II polyketide biosynthesis. The actinorhodin biosynthetic gene cluster includes a gene, actVI-orfA, that encodes a protein that belongs to the nuclear transport factor-2-like (NTF-2-like) superfamily. The function of this ActVI-ORFA protein has been a long-standing question in this field. Several hypothetical functions, including pyran ring cyclase, enzyme complex stability enhancer, and gene transcription regulator, have been proposed for ActVI-ORFA in previous studies. However, although the recent structural analysis of ActVI-ORFA revealed a solvent-accessible cavity, the protein displayed structural differences to the well-characterized cyclase SnoaL and did not possess a DNA-binding domain. The obtained crystal structure facilitates an inspection of the previous hypotheses regarding the function of ActVI-ORFA. In the present study, we investigated the effects of a series of actVI-orfA test plasmids with different mutations in an established vector/host system. Time-course analysis of dynamic metabolism profiles demonstrated that ActVI-ORFA prevented formation of shunt metabolites and may have a metabolic flux directing function, which shepherds the flux of unstable intermediates towards actinorhodin. The expression studies resulted in the isolation and structure elucidation of two new shunt metabolites from the actinorhodin pathway. Next, we utilized computational modeling to probe the active site of ActVI-ORFA and confirmed the importance of residues R76 and H78 in the flux directing functionality by expression studies. This is the first time such a function has been observed for a member of NTF-2-like superfamily in Streptomyces secondary metabolism.
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Yewhalaw, D., S. Hamels, Y. Getachew, P. R. Torgerson, M. Anagnostou, W. Legesse, H. Kloos, L. Duchateau y N. Speybroeck. "Water resource developments in Ethiopia: potential benefits and negative impacts on the environment, vector-borne diseases, and food security". Environmental Reviews 22, n.º 4 (diciembre de 2014): 364–71. http://dx.doi.org/10.1139/er-2013-0076.
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To satisfy the growing demand for electricity, Ethiopia plans to increase its electricity production five-fold between 2010 and 2015, mainly through the construction of dams. A literature review shows that while dams can boost power and agricultural production, promote economic development, and facilitate flood control, they can also lead to environmental, ecological, and socioeconomic changes. Several case studies show that dams may alter the composition and density of vectors and intermediate host species, increase the incidence of malaria schistosomiasis and possibly lymphatic filariasis, and lead to eutrophication of reservoirs, soil erosion, and earthquakes. There is evidence that dams and commercial irrigation schemes can increase soil and water degradation, vulnerability to drought, and food insecurity in riverine and lacustrine areas downstream of dams. It appears that dams in Ethiopia are also vulnerable to high soil erosion rates and earthquakes. Consequently, the current and proposed large-scale dam construction program in Ethiopia requires in-depth research to improve our understanding of the unintended negative effects of projects and to guide the location, design, and implementation of appropriate preventive and remedial programs.
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DeHart, Jason L., Joshua L. Andersen, Erik S. Zimmerman, Orly Ardon, Dong Sung An, Jana Blackett, Baek Kim y Vicente Planelles. "The Ataxia Telangiectasia-Mutated and Rad3-Related Protein Is Dispensable for Retroviral Integration". Journal of Virology 79, n.º 3 (1 de febrero de 2005): 1389–96. http://dx.doi.org/10.1128/jvi.79.3.1389-1396.2005.
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ABSTRACT Integration into the host cell DNA is an essential part of the retroviral life cycle and is required for the productive replication of a retrovirus. Retroviral integration involves cleavage of the host DNA and insertion of the viral DNA, forming an integration intermediate that contains two gaps, each with a viral 5′ flap. The flaps are then removed, and the gap is filled by as yet unidentified nuclease and polymerase activities. It is thought that repair of these gaps flanking the site of retroviral integration is achieved by host DNA repair machinery. The ATM and Rad3-related protein (ATR) is a member of the phosphatidylinositol 3 kinase-related family of protein kinases that play a major role in sensing and triggering repair of DNA lesions in mammalian cells. In an effort to examine the role of ATR in retroviral integration, we used RNA interference to selectively downregulate ATR and measured integration efficiency. In addition, we examined the possible role that Vpr may play in enhancing integration and, in particular, whether activation of ATR by Vpr (Roshal et al., J. Biol. Chem. 278:25879-25886, 2003) will favor human immunodeficiency virus type 1 integration. We conclude that cells in which ATR has been depleted are competent for retroviral integration. We also conclude that the presence of Vpr as a virion-bound protein does not enhance integration of a lentivirus vector in dividing cells.
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Zhong, Daibin, Lijing Bu, Mohamed R. Habib, Lijun Lu, Guiyun Yan y Si-Ming Zhang. "A haplotype-like, chromosome-level assembled and annotated genome of Biomphalaria glabrata, an important intermediate host of schistosomiasis and the best studied model of schistosomiasis vector snails". PLOS Neglected Tropical Diseases 18, n.º 2 (29 de febrero de 2024): e0011983. http://dx.doi.org/10.1371/journal.pntd.0011983.
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Schistosomiasis is one of the world’s most devastating parasitic diseases, afflicting 251 million people globally. The Neotropical snail Biomphalaria glabrata is an important intermediate host of the human blood fluke Schistosoma mansoni and a predominant model for schistosomiasis research. To fully exploit this model snail for biomedical research, here we report a haplotype-like, chromosome-level assembled and annotated genome of the homozygous iM line of B. glabrata that we developed at the University of New Mexico. Using multiple sequencing platforms, including Illumina, PacBio, and Omni-C sequencing, 18 sequence contact matrices representing 18 haploid chromosomes (2n = 36) were generated (337x genome coverage), and 96.5% of the scaffold sequences were anchored to the 18 chromosomes. Protein-coding genes (n = 34,559), non-coding RNAs (n = 2,406), and repetitive elements (42.52% of the genome) were predicted for the whole genome, and detailed annotations for individual chromosomes were also provided. Using this genomic resource, we have investigated the genomic structure and organization of the Toll-like receptor (TLR) and fibrinogen-domain containing protein (FReD) genes, the two important immune-related gene families. Notably, TLR-like genes are scattered on 13 chromosomes. In contrast, almost all (39 of 40) fibrinogen-related genes (FREPs) (immunoglobulin superfamily (IgSF) + fibrinogen (FBG)) are clustered within a 5-million nucleotide region on chromosome 13, yielding insight into mechanisms involved in the diversification of FREPs. This is the first genome of schistosomiasis vector snails that has been assembled at the chromosome level, annotated, and analyzed. It serves as a valuable resource for a deeper understanding of the biology of vector snails, especially Biomphalaria snails.
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Hurd, Hilary y Richard Lane. "Parasite-insect interactions: reciprocal manipulation". Parasitology 116, S1 (1998): S1—S2. http://dx.doi.org/10.1017/s0031182000084882.
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It is probably a truism to say that what seems to be a single organism is, in fact, an assemblage of organisms – for there can hardly be an individual living outside a specialized laboratory that does not have commensals or parasites living within. The insects, the most diverse and numerous group of organisms on earth are no exception, and with micro- and macro-parasites from a wide range of taxa generate a remarkable range of interspecific associations. In some cases the insect is the sole host, in others it is an intermediate host or vector. It is the latter relationship which attracts much attention when insects and arachnids transmit infectious agents to humans, their animals or crops. Knowledge of the parasites of insects provides us with an opportunity to develop novel control methods for pests. Despite the diverse and widespread nature of insect infections, their impact on human well-being and the opportunity they give us to understand the complexity of the natural world, the subject remains a surprisingly neglected field. In this volume we endeavour to draw the veil from the 'black-box' approach to the insect stages of parasite life cycles to reveal some of the complexities of these relationships and how they are currently being analysed.
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Malone, John, Robert Bergquist, Laura Rinaldi y Zhou Xiao-nong. "SCHISTOSOMIASIS: GEOSPATIAL SURVEILLANCE AND RESPONSE SYSTEMS IN SOUTHEAST ASIA". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (14 de octubre de 2016): 1409–11. http://dx.doi.org/10.5194/isprs-archives-xli-b8-1409-2016.
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Geographic information system (GIS) and remote sensing (RS) from Earth-observing satellites offer opportunities for rapid assessment of areas endemic for vector-borne diseases including estimates of populations at risk and guidance to intervention strategies. This presentation deals with GIS and RS applications for the control of schistosomiasis in China and the Philippines. It includes large-scale risk mapping including identification of suitable habitats for <i>Oncomelania hupensis</i>, the intermediate host snail of <i>Schistosoma japonicum</i>. Predictions of infection risk are discussed with reference to ecological transformations and the potential impact of climate change and the potential for long-term temperature increases in the North as well as the impact on rivers, lakes and water resource developments. Potential integration of geospatial mapping and modeling in schistosomiasis surveillance and response systems in Asia within Global Earth Observation System of Systems (GEOSS) guidelines in the health societal benefit area is discussed.
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Yan, Yongyong, Junwei Li, Yanping Chen, Lihong Wu, Haiyan Wang, Diana Diaz-Arevalo y Mingtao Zeng. "A combinatory mucosal vaccine against influenza and botulism". Journal of Immunology 196, n.º 1_Supplement (1 de mayo de 2016): 145.13. http://dx.doi.org/10.4049/jimmunol.196.supp.145.13.
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Abstract Botulinum neurotoxins (BoNTs) are the most poisonous substances known in nature and cause the life-threatening botulism. Currently, there is no FDA licensed botulism vaccine available for public use. Influenza is still an important problem for public health and current influenza vaccines are not optimal for protection against seasonal and potential pandemic influenza. Influenza virus is a negative, segmented RNA virus without DNA intermediate. This makes it safer as a vaccine delivery vector than most DNA viruses that have potential to integrate their genetic elements into host genomes. We hypothesize that a live-attenuated influenza virus expressing botulinum antigens can be developed to a dual use vaccine against both botulism and influenza. Based on influenza virus H1N1 PR8, an engineered influenza viral vector with a 2A cleavage site on NA, was constructed. Using this vector, we generated a recombinant influenza virus, PR8/HC50-rbsd, expressing the receptor binding subdomain of the heavy chain C-terminal receptor binding domain (HC50-rbsd) from BoNT/A. We tested the growth characters of the recombinant PR8/HC50-rbsd virus in chicken eggs and Madin-Darby Canine Kidney epithelial cells (MDCK), and showed that it can be produced to a titer of 5×10E6 plaque forming units/ml in chicken eggs and MDCK cells. Subsequently, mice intranasally vaccinated with the PR8/HC50-rbsd virus conferred protection against challenge with lethal doses of active BoNT/A toxin and wild type H1N1 PR8 influenza virus. Our results demonstrated that it is possible to develop a dual purpose nasal vaccine against both botulism and influenza.
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Paglinawan, Rosannie Joy, Ruby Paylangco, Jesiel Cris Paylangco, Archie Along y Florence Jhun Almadin. "Association of size structure, diet composition, endo-parasites of Snakehead fish (Channa striata, Bloch), in Lake Mainit, Caraga Region, Philippines". Southeastern Philippines Journal of Research and Development 27, n.º 2 (30 de septiembre de 2022): 1–22. http://dx.doi.org/10.53899/spjrd.v27i2.135.
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Channa striata Bloch is a type of indigenous freshwater fish abundant in Lake Mainit and it serves as a source of foods and finances of the people. This species was reported as an intermediate host of many helminth parasites. This research aimed to determine the association of endo-parasites, diet composition, and length and weight in snakehead fish C. striata Bloch in three selected municipalities along Lake Mainit, Caraga Region, Philippines. The results revealed that food items found in the stomach of the fish were mostly composed of shrimps, plant debris, fish, crab, detritus (dry & wet seasons), aquatic insects and snail (wet season). Among the seven food items, highest index of relative importance (IRI) value observed are shrimps in both wet and dry seasons. A nematode parasite was recovered in the gut of the fish samples. Out of 180 fish samples, 133 were infected with Procamallanus sp. The prevalence was higher in the dry season compared to the wet season. However, parasite intensity and diet count of C. striata Bloch. showed no significant variations between sampling sites and seasons. On the other hand, there were no significant differences between the intensity of the parasite count to the length and weight of the fish; the association between parasite count and diet count during dry and wet seasons showed a strong positive correlation. The results indicated that C. striata Bloch is susceptible to Procamallanus sp. nematode infection because of its carnivorous diet and serves as the vector or intermediate host in freshwater. Thus, more fish samples, the host’s age, host’s sex, the study gap, infection rate of the fish organs, and assessment of the physico-chemical parameters in future studies must be used.
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KAŇKOVÁ, Š., P. KODYM, D. FRYNTA, R. VAVŘINOVÁ, A. KUBĚNA y J. FLEGR. "Influence of latent toxoplasmosis on the secondary sex ratio in mice". Parasitology 134, n.º 12 (26 de julio de 2007): 1709–17. http://dx.doi.org/10.1017/s0031182007003253.
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SUMMARYThe sex ratio may be influenced by many factors, such as stress and immunosuppression, age of parents, parity and sex of preceding siblings. In animal systems, parasitism often changes the sex ratio of infected hosts, which can increase the probability of their transmission. The most common human protozoan parasite in developed countries,Toxoplasma gondii(prevalence 20%−80%), is known to change the behaviour of its intermediate hosts, thereby increasing the probability of transmission to its definitive host (the cat) by predation. The intermediate hosts, which under natural conditions are rodents, serve as the vector forToxoplasma. Therefore, we speculate thatToxoplasmacan alter the secondary sex ratio (i.e. male to female ratio in the offspring) of infected females to increase the proportion of (congenitally infected) male offspring, which are the more migratory sex in most rodent species. Here we studied the sex ratio of experimentally infected laboratory mice, expressed here as the proportion of males in the litter. In accordance with our hypothesis and results of previous retrospective cohort studies on human subjects, mice with toxoplasmosis produced a higher sex ratio than controls, in the early phase of latent infection. In the later phase of infection, mice with congenital toxoplasmosis had a lower sex ratio than controls, which is in accord with the Trivers-Willard hypothesis of sex ratio manipulation, suggesting that females in poor physical condition give birth to more female offspring.
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Zhou, Youcheng, Bin Zhong, Tao Fang, Jiming Liu, Xiaonong Zhou y Shiwu Zhang. "Application of bio-inspired control of AmphiHex-I in detection of Oncomelania hupensis, the amphibious snail intermediate host of Schistosoma japonicum". Industrial Robot: An International Journal 44, n.º 2 (20 de marzo de 2017): 242–50. http://dx.doi.org/10.1108/ir-05-2016-0151.
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Purpose This paper aims to construct a central pattern generator (CPG) network that comprises coupled nonlinear oscillators to implement diversified locomotion gaits of robot AmphiHex-I. With the gaits, AmphiHex-I will have a strong locomotion ability in an amphibious environment, which is motivated by a novel public health application to detect the amphibious snail, Oncomelania hupensis, the snail intermediate host of Schistosoma japonicum, as an amphibious robot-based tool for schistosomiasis surveillance and response in the future. Design/methodology/approach First, the basis neural network was built by adopting six Hopf nonlinear oscillators which corresponded to six legs. Then, the correlation between the self-excited harmonic output signals generated from CPGs and various gaits was established. In view of requirements on its field application, the authors added a telecontrol system and an on-board battery to support the real-life remote control and a high-definition camera and a global positioning system module to acquire images and position information. Finally, the authors conducted the testing experiments on several tasks, e.g. detecting the distribution of Oncomelania hupensis snails. Findings The results demonstrate that the CPG is effective in controlling the robot’s diversified locomotion gaits. In addition, the robot is capable of fulfilling several testing tasks in the experiments. Originality/value The research provides a method based on CPG to control a hexapod robot with multiple motion patterns, which can effectively overcome the difficulty of motion control simply by changing certain mathematical parameters of a nonlinear equation, such as frequency, phase difference and offset angle, so as to realize the gait transitions. Also, using such a robot to probe the distribution of snails offers another way to tackle this laborious job, especially in some odious terrains, which will hence broaden the application of AmphiHex-I to vector surveillance in the fields of public health.