Academic literature on the topic 'Myrmecia pilosula'

Background: Myrmecia pilosula (the jack jumper ant, JJA) is the principal cause of ant venom anaphylaxis in Australia. Whereas honeybee and wasp venom allergy can be treated by venom immunotherapy (VIT), no such treatment is available for ant sting allergy. In addition, information on the natural history of JJA sting allergy is required to identify those most likely to benefit from immunotherapy. The main objectives of this research were to establish: (i) the prevalence, natural history and determinants of reaction severity for JJA allergy, and; (ii) the efficacy and tolerability of JJA VIT. Methods: A search of the Royal Hobart Hospital (RHH) forensic register, a random telephone survey, and a review of emergency department (ED) presentations were performed. Three hundred eighty-eight JJA allergic volunteers were assessed, including serum venom-specific IgE RAST, and then followed up for accidental stings over a 4-year period. Finally, a randomised double-blind, placebo-controlled, crossover trial of JJA VIT was performed. Laboratory parameters measured during the trial were; leukocyte stimulation index (SI), IL-4 production, IgE RAST, histamine release test (HRT), leukotriene release test (LRT) and basophil activation test (BAT). Intradermal venom skin testing (VST) was also performed at trial entry. Findings: The prevalence of JJA sting allergy was 2.7% in the Tasmanian population, compared to 1.4% for honeybee. People aged 35 or older had a greater risk of both sting allergy and hypotensive reactions. Four deaths were identified, all in adults with significant comorbidities. During follow-up, 79 (70%) of 113 accidental jack jumper stings caused systemic reactions. Only prior worst reaction severity predicted the severity of follow-up reactions, with the majority of people experiencing similar or less severe reactions when stung again. Sixty-eight otherwise healthy JJA allergic adult volunteers were enrolled in the clinical trial. Systemic reactions to therapy were recorded in 34% during VIT. Objectively defined systemic reactions to sting challenges arose in 1/35 after VIT (mild self-limiting urticaria only) versus 21/29 in the placebo group. Treatment with oxygen, intravenous adrenaline infusion and volume resuscitation was effective and well tolerated. Hypotension was always accompanied by a relative bradycardia, which was severe and treated with atropine in two patients. In the placebo group, only VST and HRT were predictive of sting challenge results. Although IgE RAST, leukocyte SI and IL-4 production, LRT and BAT all correlated well with VST, they did not predict sting challenge outcome. After successful VIT, venom-induced leukocyte IL-4 production tended to fall, whereas IgE RAST increased and a natural decline in HRT reactivity was reversed. Interpretation: VIT is highly effective in prevention of JJA sting anaphylaxis and is likely to be of most benefit to people with a history of severe systemic reactions, which usually occur in people aged over 35. Neurocardiogenic mechanisms &/or direct cardiac effects may be important factors in some anaphylaxis deaths. Systemic reactions to immunotherapy are common and require immediate access to resuscitation facilities. The HRT warrants further investigation as a test for selecting those most likely to benefit from VIT. None of the tests evaluated appear to be reliable markers of successful VIT.

Ants from genus Myrmecia, subfamily Myrmeciinae, are aggressive stinging insects with medical importance in Australia, especially in the endemic areas of southeast Australia and Tasmania. Venoms of Myrmecia ants can cause allergic reactions with symptoms ranging from local to systemic. In some sensitized individuals of extreme severity, even death can occur. Two major allergens, Myr p 1 and Myr p 2 had been cloned and characterized from venom of one species, Myrmecia pilosula. The aim of this thesis was to study several aspects of the allergens from venoms of Myrmecia ants.

The Jack Jumper ant (Myrmecia pilosula complex) is limited geographically to the southern parts of Australia. It has a notorious reputation with the public of Tasmania because of the high incidence of allergic reactions to its sting in this part of Australia. The ant's aggressive attack and defence behaviour increases its exposure to the human population which is exacerbated because of its habit of nesting in close proximity to urban areas. Even though this ant has a very high public profile compared to other insects, very little research has examined aspects of M pilosula that influence its exposure to the human population. In this thesis I have addressed gaps in our knowledge related to M pilosula. I have mapped their distribution, described the climatic envelope of their range and predicted their current distribution using climate parameters. On a local scale I have identified daily above ground colony activity patterns and within this, common behaviours displayed. Activity levels were not necessarily related to time of day, but did have a slight relationship with solar radiation. The exact relationship between solar radiation and colony activity has not been resolved. Other measured climatic conditions were found not to be related to ant activity. Particular behaviours displayed by M pilosula throughout a day will increase exposure to a sting event at certain times of the day. M pilosula was found to be associated with particular plant types which are used for foraging, in addition to associations between invertebrate abundance and presence of M pilosula whereby significantly more invertebrates were found on plants with M pilosula. The types of prey recovered at the nest were not reflected in arboreal samples of invertebrates associated with M pilosula. Activity at the nest surface decreases during the middle of the day. Humans are more likely to be stung at a nest in the mornings as the ants are exiting to forage, and in the afternoon when activity increases again after a lull in the middle of the day. To avoid foraging ants, humans partaldng in outdoor activities should utilise the time early in the morning before the ants begin to exit the nest and late evening when most of the ants have returned to the nest. Any outdoor activities that have to be conducted near a nest surface should be considered during the middle of the day when activity at the nest surface is at its lowest. It is likely that M pilosula forage into the night therefore the risk of sting exposure after dark should not be discounted. Due to the arboreal nature of the ant, bushwallcers should remain on pathways when possible, avoid brushing overhanging foliage and in particular, that of Eucalyptus and Acacia.

The jack jumper ant (Myrmecia pilosula), a member of the primitive Myrmecia genus of ants, is well known for its aggressive behaviour and painful, sometimes dangerous sting. However, although the ant is well known to Tasmanians, there are few published studies of its biology or ecology. This project is an attempt to address this lack of research and seeks to explore the interaction between humans and jack jumpers by understanding better the preferred habitat of the ant. Two studies were undertaken within the boundaries of the study area: Hobart City Council, Tasmania, Australia. In the first study, jack jumper nests were searched for ten times in transects, in each of the natural vegetation types. Data were collected on the presence or absence of jack jumper nests, vegetation type, vegetation structure, moss cover, bare ground cover, coarse woody debris cover, rock cover, litter cover, litter depth, and distance to nearest tree as well as observations made about each nest that was found. In the second study, residents of Hobart were surveyed using a questionnaire regarding the features of their property and whether they had ever seen a jack jumper nest or ant on their property. They were also asked to outline the circumstances in which they were stung. To analyse the data, thematic analyses, correlation analyses, analysis of variance, Wilcoxon tests, chi-square testing, logistic regression and ordination were used. The results of the study showed that, within the Hobart City Council boundary, jack jumpers are co-extensive with dry eucalypt open woodlands. These warm, dry and relatively open environments provide the ant with a combination of insolation for warmth and vegetation for food resources such as nectar and invertebrate prey. They also utilise the radiative warmth of rocks and dry soil and often . enhance their nest's thermal capacity with decorations of seeds, soil, charcoal, stones, sticks and sometimes small vertebrate bones. In a suburban context the ants are associated with native vegetation whilst utilising cracks in concrete, walls, rockeries, dry dirt and dry grassy areas to construct nests. The suburbs with a significant matrix of native vegetation such as Mt. Nelson, Fern Tree and West Hobart all contain the ants, whereas the heavily built up areas of Battery point and North Hobart do not. Humans are most likely to be stung by a jack jumper ant in their property when carrying out outdoor duties such as gardening or collecting firewood. They may also be stung whilst walking bare foot. A common sense approach should be employed in order to avoid a sting from a jack jumper. For those wishing to live in areas that do not contain the ant, the built up suburbs of Hobart are recommended.

Myrmecia pilosula (Jack Jumper) is an endemic Australian ant whose sting is a frequent cause of insect allergy in parts of South-Eastern and South-Western Australia, causing severe anaphylaxis in approximately 3% of the population. The venom of Myrmecia pilosula ant contains IgE-binding components frequently responsible for the severe anaphylactic reactions in humans. A treatment modality based on purified M. pilosula ant venom extract has been developed by members of the Tasmanian Jack Jumper Allergy Program. The treatment, known as Jack Jumper Ant Venom Immunotherapy (JJA VIT), was proven to reduce the risk of severe anaphylaxis in sensitized patients and improve patients’ Quality of Life. However, the current treatment is associated with frequent adverse reactions and long treatment duration. As the principal Pharmacist and Quality Manager responsible for the manufacture of JJA VIT products, it is my primary interest to continuously improve the quality, safety and efficacy of this important life-saving treatment, which is uniquely Australian. My review of allergic reactions to the venom of stinging ants (as detailed in Chapter 1 and Chapter 2) illustrated the burden and impact of M. pilosula venom allergy in Australia and highlights aspects of M. pilosula venom and JJA VIT that warrant further scientific investigations, which consequently shaped the objectives and research questions of this PhD thesis. This research has two general objectives that were aimed to advance this treatment modality, and I have performed several interconnected studies to answer my research questions (Chapter 3). My first research objective was to improve the quality of the JJA VIT produced. In Chapter 4 I explored the intrinsic and extrinsic factors that could influence batch-to-batch consistency and quality of pharmaceutical grade Jack Jumper ant venom (JJAV) extracts in the form of Active Pharmaceutical Ingredients, particularly with respect to their IgE-binding components and activities. In this analysis, I found that components of the venom with molecular weight of >20 kDa are significantly affected by elevated temperature above 40°C. Notably, these venom components are capable of binding to IgE and they were of unknown identity, and their identities are revealed in Chapter 5. I analysed the proteome and allergenome of JJAV separated using a combination of various gel electrophoresis and liquid chromatography techniques. To help divulge the identity of novel JJAV components capable of binding IgE, I employed a tandem Mass Spectrometry technique. From this study, I identified 17 novel JJAV proteins, including two glycoproteins, and confirmed the presence of four known Myr p and pilosulin peptides in JJAV. Most of the newly identified IgE-binding proteins were enzymes, including phospholipase A2, hyaluronidase, arginine kinase, and dipeptidyl peptidase IV. My second research objective was to improve the safety and efficacy of JJA VIT. For this purpose, I analysed the response of subjects undergoing JJA VIT with respect to their IgE-binding recognition to JJAV components pre-treatment and I correlated this information with treatment tolerability and efficacy. I subsequently linked this clinical data with the various JJAV components identified via tandem Mass Spectrometry and report my results in Chapter 5. In this study, I established correlations between recognition of certain IgE-binding bands with JJAV-specific IgE titre by ImmunoCAP, intradermal test threshold, and treatment-related issues. Finally, driven by the relative difficulty in obtaining pharmaceutical grade JJAV extracts and the recent increase in demand to treat patients with JJAV allergy within Tasmania and interstate, I explored the safety and efficacy of treatment with low-dose JJA VIT using Advax™ adjuvant. In order to enable a clinical trial using this novel combination product, I performed fundamental pharmaceutical and immunological studies. In Chapter 6 I report the physicochemical and microbiological stability and murine immunogenicity of low-dose JJA VIT in combination with Advax adjuvant. I observed that JJA VIT formulated with Advax is both physicochemically and microbiologically stable for at least 2 days when stored at 4 and 25°C, with a trend for an increase in allergenic potency observed beyond 2 days of storage. Importantly, JJA VIT formulated with Advax significantly increased the production of JJAV-specific IgG, consistent with a JJAV antigen-sparing effect of the adjuvant, which supports the use of Advax adjuvant with JJA VIT in future clinical trials. Overall, my PhD project has advanced our knowledge on the pharmaceutical and immunological aspects of JJA VIT and provides a robust platform to enhance the quality, safety and efficacy of this life-saving treatment modality.