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Journal articles on the topic 'Pathogenicity of H.influenzae'

Author: Grafiati

Published: 4 June 2021

Last updated: 13 February 2022

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1

Martin, Kimberly, Gregory Morlin, Arnold Smith, Andrea Nordyke, Abraham Eisenstark, and Miriam Golomb. "The Tryptophanase Gene Cluster of Haemophilus influenzae Type b: Evidence for Horizontal Gene Transfer." Journal of Bacteriology 180, no. 1 (January 1, 1998): 107–18. http://dx.doi.org/10.1128/jb.180.1.107-118.1998.

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ABSTRACT Among strains of Haemophilus influenzae, the ability to catabolize tryptophan (as detected by indole production) varies and is correlated with pathogenicity. Tryptophan catabolism is widespread (70 to 75%) among harmless respiratory isolates but is nearly universal (94 to 100%) among strains causing serious disease, including meningitis. As a first step in investigating the relationship between tryptophan catabolism and virulence, we have identified genes in pathogenic H. influenzae which are homologous to the tryptophanase (tna) operon of Escherichia coli. The tna genes are located on a 3.1-kb fragment betweennlpD and mutS in the H. influenzaetype b (Eagan) genome, are flanked by 43-bp direct repeats of an uptake signal sequence downstream from nlpD, and appear to have been inserted as a mobile unit within this sequence. The organization of this insertion is reminiscent of pathogenicity islands. Thetna cluster is found at the same map location in all indole-positive strains of H. influenzae surveyed and is absent from reference type d and e genomes. In contrast to H. influenzae, most other Haemophilus species lacktna genes. Phylogenetic comparisons suggest that thetna cluster was acquired by intergeneric lateral transfer, either by H. influenzae or a recent ancestor, and thatE. coli may have acquired its tnaA gene from a related source. Genomes of virulent H. influenzae resemble those of pathogenic enterics in having an island of laterally transferred DNA next to mutS.

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2

Allen, Simon, Anthony Zaleski, Jason W. Johnston, Bradford W. Gibson, and Michael A. Apicella. "Novel Sialic Acid Transporter of Haemophilus influenzae." Infection and Immunity 73, no. 9 (September 2005): 5291–300. http://dx.doi.org/10.1128/iai.73.9.5291-5300.2005.

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ABSTRACT Nontypeable Haemophilus influenzae is an opportunistic pathogen and a common cause of otitis media in children and of chronic bronchitis and pneumonia in patients with chronic obstructive pulmonary disease. The lipooligosaccharides, a major component of the outer membrane of H. influenzae, play an important role in microbial virulence and pathogenicity. N-Acetylneuraminic acid (sialic acid) can be incorporated into the lipooligosaccharides as a terminal nonreducing sugar. Although much of the pathway of sialic acid incorporation into lipooligosaccharides is understood, the transporter responsible for N-acetylneuraminic acid uptake in H. influenzae has yet to be characterized. In this paper we demonstrate that this transporter is a novel sugar transporter of the tripartite ATP-independent periplasmic transporter family. In the absence of this transporter, H. influenzae cannot incorporate sialic acid into its lipooligosaccharides, making the organism unable to survive when exposed to human serum and causing reduced viability in biofilm growth.

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3

Doyle, Daniel, Raynell Lang, and Oscar E. Larios. "Atypical presentation of right-sided native valve infective endocarditis." Official Journal of the Association of Medical Microbiology and Infectious Disease Canada 6, no. 2 (July 2021): 163–67. http://dx.doi.org/10.3138/jammi-2020-0033.

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A previously healthy 55-year-old man presented to hospital with 10 days of progressive dyspnea with fever, night sweats, and a productive cough and no history of recreational drug use or occupational or animal exposures. His wife had developed similar symptoms 2 weeks earlier but had since recovered. Physical exam revealed a new systolic murmur best heard at the left lower sternal border. Transesophageal echocardiogram demonstrated severe tricuspid regurgitation with a small vegetation. Blood cultures were positive for non-typeable Haemophilus influenzae. This case illustrates the necessity of both timely and proficient diagnosis of H. influenzae infection and the unique challenges associated with detecting H. influenzae–related pathology. Clinicians should be aware of the variable presentations of Haemophilus infection, including respiratory infection, neurological infection, and infective endocarditis. Given the fastidious nature of H. influenzae and variability between subtype pathogenicity, microbiology laboratories require tools to culture and differentiate Haemophilus species.

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Mhlanga-Mutangadura, Tendai, Gregory Morlin, Arnold L. Smith, Abraham Eisenstark, and Miriam Golomb. "Evolution of the Major Pilus Gene Cluster ofHaemophilus influenzae." Journal of Bacteriology 180, no. 17 (September 1, 1998): 4693–703. http://dx.doi.org/10.1128/jb.180.17.4693-4703.1998.

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ABSTRACT Haemophilus influenzae is a ubiquitous colonizer of the human respiratory tract and causes diseases ranging from otitis media to meningitis. Many H. influenzae isolates express pili (fimbriae), which mediate adherence to epithelial cells and facilitate colonization. The pilus gene (hif) cluster of H. influenzae type b maps between purE andpepN and resembles a pathogenicity island: it is present in invasive strains, absent from the nonpathogenic Rd strain, and flanked by direct repeats of sequence at the insertion site. To investigate the evolution and role in pathogenesis of the hif cluster, we compared the purE-pepN regions of various H. influenzae laboratory strains and clinical isolates. Unlike Rd, most strains had an insert at this site, which usually was the only chromosomal locus of hif DNA. The inserts are diverse in length and organization: among 20 strains, nine different arrangements were found. Several nontypeable isolates lack hif genes but have two conserved open reading frames (hicA andhicB) upstream of purE; their inferred products are small proteins with no data bank homologs. Other isolates havehif genes but lack hic DNA or have combinations of hif and hic genes. By comparing these arrangements, we have reconstructed a hypothetical ancestral genotype, the extended hif cluster. The hif region of INT1, an invasive nontypeable isolate, resembles the hypothetical ancestor. We propose that a progenitor strain acquired the extended cluster by horizontal transfer and that other variants arose as deletions. The structure of the hif cluster may correlate with colonization site or pathogenicity.

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5

Gomez-De-Leon, Patricia, Jose I. Santos, Javier Caballero, Demostenes Gomez, Luz E. Espinosa, Isabel Moreno, Daniel Piñero, and Alejandro Cravioto. "Genomic Variability of Haemophilus influenzae Isolated from Mexican Children Determined by Using Enterobacterial Repetitive Intergenic Consensus Sequences and PCR." Journal of Clinical Microbiology 38, no. 7 (2000): 2504–11. http://dx.doi.org/10.1128/jcm.38.7.2504-2511.2000.

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Genomic fingerprints from 92 capsulated and noncapsulated strains of Haemophilus influenzae from Mexican children with different diseases and healthy carriers were generated by PCR using the enterobacterial repetitive intergenic consensus (ERIC) sequences. A cluster analysis by the unweighted pair-group method with arithmetic averages based on the overall similarity as estimated from the characteristics of the genomic fingerprints, was conducted to group the strains. A total of 69 fingerprint patterns were detected in theH. influenzae strains. Isolates from patients with different diseases were represented by a variety of patterns, which clustered into two major groups. Of the 37 strains isolated from cases of meningitis, 24 shared patterns and were clustered into five groups within a similarity level of 1.0. One fragment of 1.25 kb was common to all meningitis strains. H. influenzae strains from healthy carriers presented fingerprint patterns different from those found in strains from sick children. Isolates from healthy individuals were more variable and were distributed differently from those from patients. The results show that ERIC-PCR provides a powerful tool for the determination of the distinctive pathogenicity potentials of H. influenzae strains and encourage its use for molecular epidemiology investigations.

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6

Bergman, Nicholas H., and Brian J. Akerley. "Position-Based Scanning for Comparative Genomics and Identification of Genetic Islands in Haemophilus influenzae Type b." Infection and Immunity 71, no. 3 (March 2003): 1098–108. http://dx.doi.org/10.1128/iai.71.3.1098-1108.2003.

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ABSTRACT Bacteria exhibit extensive genetic heterogeneity within species. In many cases, these differences account for virulence properties unique to specific strains. Several such loci have been discovered in the genome of the type b serotype of Haemophilus influenzae, a human pathogen able to cause meningitis, pneumonia, and septicemia. Here we report application of a PCR-based scanning procedure to compare the genome of a virulent type b (Hib) strain with that of the laboratory-passaged Rd KW20 strain for which a complete genome sequence is available. We have identified seven DNA segments or H. influenzae genetic islands (HiGIs) present in the type b genome and absent from the Rd genome. These segments vary in size and content and show signs of horizontal gene transfer in that their percent G+C content differs from that of the rest of the H. influenzae genome, they contain genes similar to those found on phages or other mobile elements, or they are flanked by DNA repeats. Several of these loci represent potential pathogenicity islands, because they contain genes likely to mediate interactions with the host. These newly identified genetic islands provide areas of investigation into both the evolution and pathogenesis of H. influenzae. In addition, the genome scanning approach developed to identify these islands provides a rapid means to compare the genomes of phenotypically diverse bacterial strains once the genome sequence of one representative strain has been determined.

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7

Brook, Itzhak. "Microbiology and antimicrobial management of sinusitis." Journal of Laryngology & Otology 119, no. 4 (April 2005): 251–58. http://dx.doi.org/10.1258/0022215054020304.

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Sinusitis generally develops as a complication of viral or allergic inflammation of the upper respiratory tract. The bacterial pathogens in acute sinusitis are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, while anaerobic bacteria and Staphylococcus aureus are predominant in chronic sinusitis. Pseudomonas aeruginosa has emerged as a potential pathogen in immunocompromised patients and in those who have nasal tubes or catheters, or are intubated. Many of these organisms recovered from sinusitis became resistant to penicillins either through the production of beta-lactamase (H. influenzae, M. catarrhalis, S. aureus, Fusobacterium spp., and Prevotella spp) or through changes in the penicillin-binding protein (S. pneumoniae). The pathogenicity of beta-lactamase-producing bacteria is expressed directly through their ability to cause infections, and indirectly through the production of betalactamase. The indirect pathogenicity is conveyed not only by surviving penicillin therapy, but also by ‘shielding’ penicillin-susceptible pathogens from the drug. The direct and indirect virulent characteristics of these bacteria require the administration of appropriate antimicrobial therapy directed against all pathogens in mixed infections. The antimicrobials that are the most effective in management of acute sinusitis are amoxycillin-clavulanate (given in a high dose), the newer quinolones (gatifloxacin, moxifloxacin) and the second generation cephalosporins (cefuroxime, cefpodoxime, cefprozil or cefdinir). The antimicrobials that are the most effective in management of chronic sinusitis are amoxycillinclavulanate, clindamycin and the combination of metronidazole and a penicillin.

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8

Read, Timothy D., Sarah W. Satola, and Monica M. Farley. "Nucleotide Sequence Analysis of Hypervariable Junctions of Haemophilus influenzae Pilus Gene Clusters." Infection and Immunity 68, no. 12 (December 1, 2000): 6896–902. http://dx.doi.org/10.1128/iai.68.12.6896-6902.2000.

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ABSTRACT Haemophilus influenzae pili are surface structures that promote attachment to human epithelial cells. The five genes that encode pili, hifABCDE, are found inserted in genomes either between pmbA and hpt (hif-1) or between purE and pepN (hif-2). We determined the sequence between the ends of the pilus clusters and bordering genes in a number of H. influenzae strains. The junctions of the hif-1 cluster (limited to biogroup aegyptius isolates) are structurally simple. In contrast,hif-2 junctions are highly diverse, complex assemblies of conserved intergenic sequences (including genes hicA andhicB) with evidence of frequent recombination. Variation athif-2 junctions seems to be tied to multiple copies of a 23-bp Haemophilus intergenic dyad sequence. Thehif-1 cluster appears to have originated in biogroup aegyptius strains from invasion of the hpt-pmbA region by a DNA template containing the hif-2 genes with termini in the hairpin loop of flanking intergenic dyad sequences. The pilus gene clusters are an interesting model of a mobile “pathogenicity island” not associated with a phage, transposon, or insertion element.

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9

Twabela, Augustin, Masatoshi Okamatsu, Keita Matsuno, Norikazu Isoda, and Yoshihiro Sakoda. "Evaluation of Baloxavir Marboxil and Peramivir for the Treatment of High Pathogenicity Avian Influenza in Chickens." Viruses 12, no. 12 (December 8, 2020): 1407. http://dx.doi.org/10.3390/v12121407.

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Control measures in the case of high pathogenicity avian influenza (HPAI) outbreaks in poultry include culling, surveillance, and biosecurity; wild birds in captivity may also be culled, although some rare bird species should be rescued for conservation. In this study, two anti-influenza drugs, baloxavir marboxil (BXM) and peramivir (PR), used in humans, were examined in treating HPAI in birds, using chickens as a model. Chickens were infected with H5N6 HPAI virus and were treated immediately or 24 h from challenge with 20 mg/kg BXM or PR twice a day for five days. As per our findings, BXM significantly reduced virus replication in organs and provided full protection to chickens compared with that induced by PR. In the 24-h-delayed treatment, neither drug completely inhibited virus replication nor ensured the survival of infected chickens. A single administration of 2.5 mg/kg of BXM was determined as the minimum dose required to fully protect chickens from HPAI virus; the concentration of baloxavir acid, the active form of BXM, in chicken blood at this dose was sufficient for a 48 h antiviral effect post-administration. Thus, these data can be a starting point for the use of BXM and PR in treating captive wild birds infected with HPAI virus.

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10

Jóźwiak, Michał, Krzysztof Wyrostek, Katarzyna Domańska-Blicharz, Monika Olszewska-Tomczyk, Krzysztof Śmietanka, and Zenon Minta. "Application of FTA® Cards for detection and storage of avian influenza virus." Journal of Veterinary Research 60, no. 1 (March 1, 2016): 1–6. http://dx.doi.org/10.1515/jvetres-2016-0001.

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AbstractIntroduction: The aim of the study was to test the utility of Flinders Technology Associates filter paper (FTA® Cards) for molecular detection and storage of avian influenza virus (AIV). Material and Methods: There were two strains of AIV used in the study: low pathogenicity H7N1 and high pathogenicity H5N1 subtypes. Detection of viral material was conducted using molecular RT-PCR and rRT- PCR method. Results: The infectivity of LPAIV/H7N1 and HPAIV/H5N1 was completely inactivated within 1 h and 24 h after adsorption to FTA® Cards at room temperature, respectively. Viruses stored on FTA® Cards had detection limit approximately 1 log10 lower than live viruses. Viral RNA of both strains were detectable on the cards by rRT-PCR for a minimum of 150 d, irrespectively of storage temperatures (room temperature, -20ºC). RNA was also detected in all samples obtained from SPF chickens experimentally infected with HPAI/H5N1 on 3rd and 4th day post-infection (p.i.). Conclusion: FTA® Cards enable safe and effective alternative transport of samples for molecular diagnosis of AIV.

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11

Conly, JM, and BL Johnston. "Ode to Oseltamivir and Amantadine?" Canadian Journal of Infectious Diseases and Medical Microbiology 17, no. 1 (2006): 11–14. http://dx.doi.org/10.1155/2006/106989.

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Influenza A and B viruses are the two major types of influenza viruses that cause human epidemic disease. Influenza A viruses are further categorized into subtypes based on two surface antigens: hemagglutinin (H) and neuraminidase (N). Influenza B viruses are not categorized into subtypes (1). Influenza A viruses are found in many animal species, including humans, ducks, chickens, pigs, whales, horses and seals, whereas influenza B viruses circulate only among humans. The H antigen contains common and strain-specific antigens, demonstrates antigenic variation, and acts as a site of attachment of the virus to host cells to initiate infection (1). The N antigen contains subtype-specific antigens and also demonstrates antigenic variation between subtypes. It is a surface glycoprotein possessing enzymatic activity essential for viral replication in both influenza A and B viruses. The N antigen allows the release of newly produced virions from infected host cells, prevents the formation of viral aggregates after release from the host cells, and prevents viral inactivation by respiratory mucous (2,3). It is thought that this enzyme may also promote viral penetration into respiratory epithelial cells and may contribute to the pathogenicity of the virus by promoting production of proinflammatory cytokines such as interleukin-1 and tumour necrosis factor from macrophages (4-6).

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12

Suzuki, Koutaro, Hironao Okada, Toshihiro Itoh, Tatsuya Tada, Masaji Mase, Kikuyasu Nakamura, Masanori Kubo, and Kenji Tsukamoto. "Association of Increased Pathogenicity of Asian H5N1 Highly Pathogenic Avian Influenza Viruses in Chickens with Highly Efficient Viral Replication Accompanied by Early Destruction of Innate Immune Responses." Journal of Virology 83, no. 15 (May 20, 2009): 7475–86. http://dx.doi.org/10.1128/jvi.01434-08.

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ABSTRACT The Asian H5N1 highly pathogenic avian influenza (HPAI) viruses have been increasing in pathogenicity in diverse avian species since 1996 and are now widespread in Asian, European, and African countries. To better understand the basis of the increased pathogenicity of recent Asian H5N1 HPAI viruses in chickens, we compared the fevers and mean death times (MDTs) of chickens infected with the Asian H5N1 A/chicken/Yamaguchi/7/04 (CkYM7) strain with those infected with the H5N1 Duck/Yokohama/aq10/03 (DkYK10) strain, using a wireless thermosensor. Asian H5N1 CkYM7 caused peracute death in chickens before fever could be induced, whereas DkYK10 virus induced high fevers and had a long MDT. Real-time PCR analyses of cytokine mRNA expressions showed that CkYM7 quickly induced antiviral and proinflammatory cytokine mRNA expressions at 24 h postinfection (hpi) that suddenly decreased at 32 hpi. In contrast, these cytokine mRNA expressions increased at 24 hpi in the DkYK10 group, but decreased from 48 hpi onward to levels similar to those resulting from infection with the low-pathogenicity H5N2 A/chicken/Ibaraki/1/2004 strain. Sequential titrations of viruses in lungs, spleens, and kidneys demonstrated that CkYM7 replicated rapidly and efficiently in infected chickens and that the viral titers were more than twofold higher than those of DkYK10. CkYM7 preferentially and efficiently replicated in macrophages and vascular endothelial cells, while DkYK10 grew moderately in macrophages. These results indicate that the increased pathogenicity in chickens of the recent Asian H5N1 HPAI viruses may be associated with extremely rapid and high replication of the virus in macrophages and vascular endothelial cells, which resulted in disruption of the thermoregulation system and innate immune responses.

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13

Chow, CW, N. Senathiragah, M. Rawji, M. Chan, LR Lee-Pack, and CK Chan. "Interim Report on Drug Utilization Review of Community Acquired, Nursing Home Acquired and Nosocomial Pneumonia: Clinical, Bacteriological and Radiological Spectrum." Canadian Journal of Infectious Diseases 5, suppl c (1994): 20C—27C. http://dx.doi.org/10.1155/1994/651452.

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OBJECTIVES: To review the epidemiology of community acquired, nursing home acquired and nosocomial pneumonia in terms of clinical. bacteriological and radiological features and to examine the spectrum of and response to antimicrobial agents used in its management.DESIGN: A retrospective review of all hospital records with pneumonia coded in the discharge diagnoses over a five-year period from April 1987 to March 1993.SETTING: University-affiliated, community-based hospital with a mixed primary to tertiary referral base.PATIENT SELECTION: Patients included in the study were all patients with a diagnosis of pneumonia as identified by computer records of diagnostic codes of all discharges: patients with a specific diagnosis of Pneumocystis carinii pneumonia were excluded. One thousand seven hundred and eighty-two patients out of 74.435 discharges over the five-year period met the inclusion criteria.RESULTS: The initial 1300 of the 1782 cases of pneumonia are included in this interim report. Mean age was 65 years (range 16 to 103) wilh 60% men and 40% women. Sixty-two percent of all cases were community acquired, 29% were hospital acquired and 9% were nursing home acquired. One thousand two hundred and sixty (97%) patients had al least one concomitant medical condition. mainly cardiac disease. alcoholism and chronic obstructive lung disease. Chest roentgenogram was abnormal in 98%. Cultures of sputum, bronchoalveolar lavage fluid, blood and/or serology revealed positive results in 785. The most common pathogens were Streptococcus pneumoniae (154). Haemophilus influenzae (147). Staphylococcus aureus (111) and Pseudomonas aeruginosa (100). In the group with community acquired pneumonia, S pneumoniae and H influenzae predominated. In the hospital acquired pneumonia group S aureus and P aeruginosa were more common. although S pneumoniae remains a significant pathogen. In the nursing home acquired pneumonia group. Gram-negative agents were the most common. The pattern of antimicrobial agents used, usually begun empirically when culture results are pending. showed that the majority of patients was treated with combination antibiotics for both Gram-positive and Gram-negative coverage. Ceftriaxone was usually prescribed with either erythromycin or clindamycin. In about half the patients. the ceftriaxone dose was 1 g per clay. Ninety-six (7%) patients developed complications of pneumonia and 207 (16%) patients required intensive care unit admission. Nine hundred and fifty-nine (73%) patients were cured or improved at time of discharge, 21 ( 1.5%) patients discharged themselves against medical advice and 320 (25%) patients died during admission to hospital, of whom 165 cases had pneumonia listed as a cause on the death certificate.CONCLUSIONS: Pneumonia remains a significant illness with high morbidity and mortality. Those affected and requiring hospitalization are elderly and ill. The most common pathogens overall continue to be S pneumoniae and H influenzae, although Gram-negative organisms and S aureus were also significant agents in nosocomial and nursing home acquired pneumonia. The high percentage of Gram-negative infections in the community acquired group has not been previously described and may represent a change in the pattern of pathogens affecting this group. Three of the 53 community acquired cases in whom P aeruginosa was implicated were detected on blood cultures and were definitely pathogens. Ten of the 53 patients had underlying bronchiectasis or cystic fibrosis and one patient had a history of hematogenous malignancy. Whether the finding of P aeruginosa represents true pathogenicity or colonization in the 53 cases is difficult to differentiate in a retrospective fashion. However. all but two received antibiotic therapy. and 10 of the 40 survivors in this subgroup received adequate coverage for pseudomonas. Although yield from routine investigations is only 60% (785 of 1300 patients in this study), cultures of blood and sputum should be sent in all patients as it may help to narrow choice of antimicrobial agents and aid in oral step-down selection . Only in select patients should serum serology and more costly and invasive procedures such as bronchoscopy and thoracocentesis be done. It appears that the current pattern of antimicrobial use is appropriate for management of pneumonia given the pattern of offending organisms seen. In the present study, pragmatic use of ceftriaxone at 1 g/24h in these sick patients appeared to result in a therapeutic outcome similar to other antibiotic combination therapy.

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Trinh, Thuy-Tien Thi, Indira Tiwari, Kaliannan Durairaj, Bao Tuan Duong, Anh Thi Viet Nguyen, Hien Thi Tuong, Vui Thi Hoang, et al. "Genetic Characterization and Pathogenesis of Avian Influenza Virus H7N3 Isolated from Spot-Billed Ducks in South Korea, Early 2019." Viruses 13, no. 5 (May 7, 2021): 856. http://dx.doi.org/10.3390/v13050856.

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Low-pathogenicity avian influenza viruses (LPAIV) introduced by migratory birds circulate in wild birds and can be transmitted to poultry. These viruses can mutate to become highly pathogenic avian influenza viruses causing severe disease and death in poultry. In March 2019, an H7N3 avian influenza virus—A/Spot-billed duck/South Korea/WKU2019-1/2019 (H7N3)—was isolated from spot-billed ducks in South Korea. This study aimed to evaluate the phylogenetic and mutational analysis of this isolate. Molecular analysis revealed that the genes for HA (hemagglutinin) and NA (neuraminidase) of this strain belonged to the Central Asian lineage, whereas genes for other internal proteins such as polymerase basic protein 1 (PB1), PB2, nucleoprotein, polymerase acidic protein, matrix protein, and non-structural protein belonged to that of the Korean lineage. In addition, a monobasic amino acid (PQIEPR/GLF) at the HA cleavage site, and the non-deletion of the stalk region in the NA gene indicated that this isolate was a typical LPAIV. Nucleotide sequence similarity analysis of HA revealed that the highest homology (99.51%) of this isolate is to that of A/common teal/Shanghai/CM1216/2017 (H7N7), and amino acid sequence of NA (99.48%) was closely related to that of A/teal/Egypt/MB-D-487OP/2016 (H7N3). An in vitro propagation of the A/Spot-billed duck/South Korea/WKU2019-1/2019 (H7N3) virus showed highest (7.38 Log10 TCID50/mL) virus titer at 60 h post-infection, and in experimental mouse lungs, the virus was detected at six days’ post-infection. Our study characterizes genetic mutations, as well as pathogenesis in both in vitro and in vivo model of a new Korea H7N3 viruses in 2019, carrying multiple potential mutations to become highly pathogenic and develop an ability to infect humans; thus, emphasizing the need for routine surveillance of avian influenza viruses in wild birds.

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Sakuma, Saki, Yuko Uchida, Momoyo Kajita, Taichiro Tanikawa, Junki Mine, Ryota Tsunekuni, and Takehiko Saito. "First Outbreak of an H5N8 Highly Pathogenic Avian Influenza Virus on a Chicken Farm in Japan in 2020." Viruses 13, no. 3 (March 16, 2021): 489. http://dx.doi.org/10.3390/v13030489.

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On 5 November 2020, a confirmed outbreak due to an H5N8 highly pathogenic avian influenza virus (HPAIV) occurred at an egg-hen farm in Kagawa prefecture (western Japan). This virus, A/chicken/Kagawa/11C/2020 (Kagawa11C2020), was the first HPAI poultry isolate in Japan in 2020 and had multiple basic amino acids—a motif conferring high pathogenicity to chickens—at the hemagglutinin cleavage site. Mortality of chickens was 100% through intravenous inoculation tests performed according to World Organization for Animal Health criteria. Phylogenetic analysis showed that the hemagglutinin of Kagawa11C2020 belongs to clade 2.3.4.4B of the H5 Goose/Guangdong lineage and clusters with H5N8 HPAIVs isolated from wild bird feces collected in Hokkaido (Japan) and Korea in October 2020. These H5N8 HPAIVs are closely related to H5N8 HPAIVs isolated in European countries during the winter of 2019–2020. Intranasal inoculation of chickens with 106 fifty-percent egg infectious doses of Kagawa11C2020 revealed that the 50% chicken lethal dose was 104.63 and the mean time to death was 134.4 h. All infected chickens demonstrated viral shedding beginning on 2 dpi—before clinical signs were observed. These results suggest that affected chickens could transmit Kagawa11C2020 to surrounding chickens in the absence of clinical signs for several days before they died.

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Spackman, Erica, David E. Swayne, Mary J. Pantin‐Jackwood, Xiu‐Feng Wan, Mia K. Torchetti, Mohammad Hassan, David L. Suarez, and Mariana Sá e Silva. "Variation in protection of four divergent avian influenza virus vaccine seed strains against eight clade 2.2.1 and 2.2.1.1. E gyptian H 5 N 1 high pathogenicity variants in poultry." Influenza and Other Respiratory Viruses 8, no. 6 (October 3, 2014): 654–62. http://dx.doi.org/10.1111/irv.12290.

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17

Trinh, Thuy-Tien Thi, Bao Tuan Duong, Anh Thi Viet Nguyen, Hien Thi Tuong, Vui Thi Hoang, Duong Duc Than, SunJeong Nam, et al. "Emergence of Novel Reassortant H1N1 Avian Influenza Viruses in Korean Wild Ducks in 2018 and 2019." Viruses 13, no. 1 (December 26, 2020): 30. http://dx.doi.org/10.3390/v13010030.

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Influenza A virus subtype H1N1 has caused global pandemics like the “Spanish flu” in 1918 and the 2009 H1N1 pandemic several times. H1N1 remains in circulation and survives in multiple animal sources, including wild birds. Surveillance during the winter of 2018–2019 in Korea revealed two H1N1 isolates in samples collected from wild bird feces: KNU18-64 (A/Greater white-fronted goose/South Korea/KNU18-64/2018(H1N1)) and WKU19-4 (A/wild bird/South Korea/WKU19-4/2019(H1N1)). Phylogenetic analysis indicated that M gene of KNU18-64(H1N1) isolate resembles that of the Alaskan avian influenza virus, whereas WKU19-4(H1N1) appears to be closer to the Mongolian virus. Molecular characterization revealed that they harbor the amino acid sequence PSIQRS↓GLF and are low-pathogenicity influenza viruses. In particular, the two isolates harbored three different mutation sites, indicating that they have different virulence characteristics. The mutations in the PB1-F2 and PA protein of WKU19-4(H1N1) indicate increasing polymerase activity. These results corroborate the kinetic growth data for WKU19-4 in MDCK cells: a dramatic increase in the viral titer after 12 h post-inoculation compared with that in the control group H1N1 (CA/04/09(pdm09)). The KNU18-64(H1N1) isolate carries mutations indicating an increase in mammal adaptation; this characterization was confirmed by the animal study in mice. The KNU18-64(H1N1) group showed the presence of viruses in the lungs at days 3 and 6 post-infection, with titers of 2.71 ± 0.16 and 3.71 ± 0.25 log10(TCID50/mL), respectively, whereas the virus was only detected in the WKU19-4(H1N1) group at day 6 post-infection, with a lower titer of 2.75 ± 0.51 log10(TCID50/mL). The present study supports the theory that there is a relationship between Korea and America with regard to reassortment to produce novel viral strains. Therefore, there is a need for increased surveillance of influenza virus circulation in free-flying and wild land-based birds in Korea, particularly with regard to Alaskan and Asian strains.

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Kolker, Eugene, Samuel Purvine, Alex Picone, Tim Cherny, Brian J. Akerley, Robert S. Munson, Bernhard O. Palsson, Dayle A. Daines, and Arnold L. Smith. "H. influenzae Consortium: Integrative Study of H. influenzae-Human Interactions." OMICS: A Journal of Integrative Biology 6, no. 4 (October 2002): 341–48. http://dx.doi.org/10.1089/153623102321112764.

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Nguyen, Ngoc Minh, Haan Woo Sung, Ki-Jung Yun, Hyun Park, and Seon-Ju Yeo. "Genetic Characterization of a Novel North American-Origin Avian Influenza A (H6N5) Virus Isolated from Bean Goose of South Korea in 2018." Viruses 12, no. 7 (July 17, 2020): 774. http://dx.doi.org/10.3390/v12070774.

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The complex overlap in waterfowl migratory pathways across the world has established numerous occurrences of genetic reassortment and intercontinental spread of avian influenza virus (AIV) over long distances, thereby calling for huge efforts and targeted surveillance for infection control. During annual surveillance in South Korea in 2018, a novel avian influenza H6N5 (K6) subtype was isolated from the fecal sample of wild bird. Genomic characterization using a phylogenetic tree indicated the K6 virus to be of North American-origin, with partial homology to an H6N5 strain, A/Aix galericulata/South Korea/K17-1638-5/2017 (K17). A monobasic residue at the HA cleavage site and absence of a notable mutation at the HA receptor-binding site suggested the isolate to be of low pathogenicity. However, molecular analysis revealed the E119V mutation in the NA gene and a human host marker mutation E382D in the polymerase acidic (PA) gene, implying their susceptibility to neuraminidase inhibitors and potential infectivity in humans, respectively. For comparison, K6 and K17 were found to be dissimilar for various mutations, such as A274T of PB2, S375N/T of PB1, or V105M of NP, each concerning the increased virulence of K6 in mammalian system. Moreover, kinetic data presented the highest viral titer of this H6N5 isolate at 106.37 log10TCID50 after 48 h of infection, thus proving efficient adaptability for replication in a mammalian system in vitro. The mouse virus challenge study showed insignificant influence on the total body weight, while viral load shedding in lungs peaked at 1.88 ± 0.21 log10 TICD50/mL, six days post infection. The intercontinental transmission of viruses from North America may continuously be present in Korea, thereby providing constant opportunities for virus reassortment with local resident AIVs; these results hint at the increased potential risk of host jumping capabilities of the new isolates. Our findings reinforce the demand for regular surveillance, not only in Korea but also along the flyways in Alaska.

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20

&NA;. "H. influenzae - an unsolved problem?" Inpharma Weekly &NA;, no. 883 (April 1993): 4. http://dx.doi.org/10.2165/00128413-199308830-00005.

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Marwick, Charles. "H influenzae Vaccines Gain Favor." JAMA: The Journal of the American Medical Association 264, no. 11 (September 19, 1990): 1375. http://dx.doi.org/10.1001/jama.1990.03450110011002.

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Brenner, Steven E., Tim Hubbard, Alexey Murzin, and Cyrus Chothia. "Gene duplications in H. influenzae." Nature 378, no. 6553 (November 1995): 140. http://dx.doi.org/10.1038/378140a0.

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23

&NA;. "Vaccination eliminates H. influenzae meningitis." Inpharma Weekly &NA;, no. 855 (September 1992): 18. http://dx.doi.org/10.2165/00128413-199208550-00031.

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&NA;. "VACCINATING CHILDREN AGAINST H. INFLUENZAE." AJN, American Journal of Nursing 85, no. 6 (June 1985): 642. http://dx.doi.org/10.1097/00000446-198506000-00005.

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25

Marwick, C. "H influenzae vaccines gain favor." JAMA: The Journal of the American Medical Association 264, no. 11 (September 19, 1990): 1375. http://dx.doi.org/10.1001/jama.264.11.1375.

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26

Pinkett, Heather W. "ABC Transporters in H. Influenzae." Biophysical Journal 106, no. 2 (January 2014): 227a—228a. http://dx.doi.org/10.1016/j.bpj.2013.11.1332.

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&NA;. "Concerns over H. influenzae B vaccine." Reactions Weekly &NA;, no. 435 (January 1993): 4. http://dx.doi.org/10.2165/00128415-199304350-00009.

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Neville, Stephen, George Toouli, and Gerry Williams. "H. influenzae in genital tract specimens." Medical Journal of Australia 142, no. 9 (April 1985): 531. http://dx.doi.org/10.5694/j.1326-5377.1985.tb133214.x.

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&NA;. "Concerns over H. influenzae B vaccine." Inpharma Weekly &NA;, no. 871 (January 1993): 2. http://dx.doi.org/10.2165/00128413-199308710-00002.

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30

Boody, R., E. R. Moxon, R. T. Mayon-White, M. P. Slack, and J. A. Macfarlane. "Vaccination against H influenzae type b." BMJ 306, no. 6869 (January 2, 1993): 63. http://dx.doi.org/10.1136/bmj.306.6869.63-c.

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Bower, B. D. "AMPICILLIN ‘FAILURE’ IN H. INFLUENZAE MENINGITIS." Developmental Medicine & Child Neurology 15, no. 6 (November 12, 2008): 813–14. http://dx.doi.org/10.1111/j.1469-8749.1973.tb04921.x.

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Gamstorp, Ingrid, and Ingmar Klockhoff. "HEARING LOSS AFTER H. INFLUENZAE MENINGITIS." Developmental Medicine & Child Neurology 16, no. 5 (November 12, 2008): 678–79. http://dx.doi.org/10.1111/j.1469-8749.1974.tb04191.x.

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Bachman, David S. "Hearing Loss After H. influenzae Meningitis." Developmental Medicine & Child Neurology 17, no. 1 (November 12, 2008): 119–20. http://dx.doi.org/10.1111/j.1469-8749.1975.tb04976.x.

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34

Pettigrew, M. M., B. Foxman, C. F. Marrs, and J. R. Gilsdorf. "Identification of the Lipooligosaccharide Biosynthesis Gene lic2B as a Putative Virulence Factor in Strains of Nontypeable Haemophilus influenzae That Cause Otitis Media." Infection and Immunity 70, no. 7 (July 2002): 3551–56. http://dx.doi.org/10.1128/iai.70.7.3551-3556.2002.

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ABSTRACT Nontypeable (NT) strains of Haemophilus influenzae are an important cause of acute otitis media (OM). The pathogenic process by which NT H. influenzae strains cause OM is poorly understood. In order to identify specific virulence factors important for OM pathogenesis, genomic subtraction of the NT H. influenzae middle ear isolate G622 against H. influenzae strain Rd was conducted and the resulting subtraction products were used to screen a panel of H. influenzae isolates. Subtraction identified 36 PCR fragments unique to strain G622, which were used in a preliminary screen of 48 middle ear isolates and 46 nasopharyngeal and throat isolates to identify genes found more frequently among middle ear isolates. These experiments identified a PCR fragment with high homology to the lipooligosaccharide biosynthesis gene lic2B (originally identified in an H. influenzae type b strain) among 52% of the middle ear isolates and 9% of nasopharyngeal and throat isolates. The lic2B gene cloned from NT H. influenzae strain G622 was 99% identical at the amino acid level to that of the H. influenzae type b strain RM7004. The lic2B gene was used to screen a larger panel of H. influenzae isolates including the original 48 middle ear isolates, 40 invasive type b isolates, 90 NT H. influenzae throat isolates from children attending day care, and 32 NT H. influenzae nasopharyngeal clinical isolates. The lic2B gene was found 3.7 times more frequently among middle ear isolates than in throat isolates from children attending day care. These data suggest that a specific NT H. influenzae gene is associated with OM.

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Dalhoff, A. "Activity of Moxifloxacin Against H. influenzae and H. parainfluenzae." Drugs 58, Supplement 2 (1999): 349–50. http://dx.doi.org/10.2165/00003495-199958002-00118.

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Koroleva, M. A., I. S. Koroleva, I. M. Gruber, and L. S. Cherkasova. "Phenotypic Characteristics and the Susceptibility of Haemophilus influenzae to the Antimicrobial Agents in Russia (2004 - 2016)." Epidemiology and Vaccine Prevention 16, no. 2 (April 20, 2017): 36–43. http://dx.doi.org/10.31631/2073-3046-2017-16-2-36-43.

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The aim. The study of phenotypic characteristics and dynamics of sensitivity to antibiotics Russian invasive strains H. influenzae. Materials and methods. Studied 89 Russian invasive strains H. influenzae for the period 13-year period (2004 - 2016). To study metabolic, enzymatic activity and beta-lactamase and biotype characteristics H. influenzae strains. Studied H. influenzae sensitivity to antibiotics. Results. Most strains related H. influenzae serotype b (86,1%), biotype II (69,7%), VII (16,9%), I (13,5%). Ampicillin-resistant strains accounted for 10.1%. All of them produced the enzyme beta-lactamase. Conclusion. The population of the Russian invasive ampicillin-resistant H. influenzae strains accounted for 10.1%. The mechanism of resistance to ampicillin is the production of the enzyme beta-lactamase.

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Osorio-Aguilar, Yesenia, Maria Cristina Gonzalez-Vazquez, Patricia Lozano-Zarain, Ygnacio Martinez-Laguna, Alejandro Carabarin-Lima, and Rosa del Carmen Rocha-Gracia. "Cloning and Characterization of Immunological Properties of Haemophilus influenzae Enolase." Journal of Immunology Research 2021 (June 16, 2021): 1–14. http://dx.doi.org/10.1155/2021/6629824.

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Haemophilus influenzae is a common organism of the human upper respiratory tract; this bacterium is responsible of a wide spectrum for respiratory infections and can generate invasive diseases such as meningitis and septicemia. These infections are associated with H. influenzae encapsulated serotype b. However, the incidence of invasive disease caused by nontypeable H. influenzae (NTHi) has increased in the post-H. influenzae serotype b (Hib) vaccine era. Currently, an effective vaccine against NTHi is not available; due to this, it is important to find an antigen capable to confer protection against NTHi infection. In this study, 10 linear B cell epitopes and 13 CTL epitopes and a putative plasminogen-binding motif (252FYNKENGMY260) and the presence of enolase on the surface of different strains of H. influenzae were identified in the enolase sequence of H. influenzae. Both in silico and experimental results showed that recombinant enolase from H. influenzae is immunogenic that could induce a humoral immune response; this was observed mediating the generation of specific polyclonal antibodies anti-rNTHiENO that recognize typeable and nontypeable H. influenzae strains. The immunogenic properties and the superficial localization of enolase in H. influenzae, important characteristics to be considered as a new candidate for the development of a vaccine, were demonstrated.

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Arce, Fernando Terán, Ross Carlson, James Monds, Richard Veeh, Fen Z. Hu, Philip S. Stewart, Ratnesh Lal, Garth D. Ehrlich, and Recep Avci. "Nanoscale Structural and Mechanical Properties of Nontypeable Haemophilus influenzae Biofilms." Journal of Bacteriology 191, no. 8 (February 13, 2009): 2512–20. http://dx.doi.org/10.1128/jb.01596-08.

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ABSTRACT Nontypeable Haemophilus influenzae (NTHI) bacteria are commensals in the human nasopharynx, as well as pathogens associated with a spectrum of acute and chronic infections. Two important factors that influence NTHI pathogenicity are their ability to adhere to human tissue and their ability to form biofilms. Extracellular polymeric substances (EPS) and bacterial appendages such as pili critically influence cell adhesion and intercellular cohesion during biofilm formation. Structural components in the outer cell membrane, such as lipopolysaccharides, also play a fundamental role in infection of the host organism. In spite of their importance, these pathogenic factors are not yet well characterized at the nanoscale. Here, atomic force microscopy (AFM) was used in aqueous environments to visualize structural details, including probable Hif-type pili, of live NTHI bacteria at the early stages of biofilm formation. Using single-molecule AFM-based spectroscopy, the molecular elasticities of lipooligosaccharides present on NTHI cell surfaces were analyzed and compared between two strains (PittEE and PittGG) with very different pathogenicity profiles. Furthermore, the stiffness of single cells of both strains was measured and subsequently their turgor pressure was estimated.

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Agrawal, Aarti, and Timothy F. Murphy. "Haemophilus influenzae Infections in the H. influenzae Type b Conjugate Vaccine Era." Journal of Clinical Microbiology 49, no. 11 (September 7, 2011): 3728–32. http://dx.doi.org/10.1128/jcm.05476-11.

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Slack, Mary Paulina Elizabeth. "Long Term Impact of Conjugate Vaccines on Haemophilus influenzae Meningitis: Narrative Review." Microorganisms 9, no. 5 (April 21, 2021): 886. http://dx.doi.org/10.3390/microorganisms9050886.

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H. influenzae serotype b (Hib) used to be the commonest cause of bacterial meningitis in young children. The widespread use of Hib conjugate vaccine has profoundly altered the epidemiology of H. influenzae meningitis. This short review reports on the spectrum of H. influenzae meningitis thirty years after Hib conjugate vaccine was first introduced into a National Immunization Program (NIP). Hib meningitis is now uncommon, but meningitis caused by other capsulated serotypes of H. influenzae and non-typeable strains (NTHi) should be considered. H. influenzae serotype a (Hia) has emerged as a significant cause of meningitis in Indigenous children in North America, which may necessitate a Hia conjugate vaccine. Cases of Hie, Hif, and NTHi meningitis are predominantly seen in young children and less common in older age groups. This short review reports on the spectrum of H. influenzae meningitis thirty years after Hib conjugate vaccine was first introduced into a NIP.

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Prasadarao, Nemani V., Elena Lysenko, Carol A. Wass, Kwang Sik Kim, and Jeffrey N. Weiser. "Opacity-Associated Protein A Contributes to the Binding of Haemophilus influenzae to Chang Epithelial Cells." Infection and Immunity 67, no. 8 (August 1, 1999): 4153–60. http://dx.doi.org/10.1128/iai.67.8.4153-4160.1999.

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ABSTRACT Opacity-associated protein A (OapA), which is responsible for the transparent-colony phenotype of Haemophilus influenzae, has been implicated in the colonization of the nasopharynx in an infant rat model of carriage. In this report, we show that OapA mediates attachment to Chang epithelial cells examined by using genetically defined type b and nontypeable H. influenzae strains with or without OapA. We also showed that OapA was conserved among H. influenzae strains by comparing deduced amino acid sequences. Both recombinant OapA and polyclonal anti-OapA antiserum blocked the binding of H. influenzae to Chang epithelial cells, suggesting that the interaction of H. influenzae is specific to OapA. Moreover, the binding of recombinant OapA to epithelial cells further provided evidence that OapA can promote attachment of H. influenzae. Expression of oapAgene in a nonadherent Escherichia coli strain significantly increased the binding to Chang epithelial cells, and disruption of theoapA gene with kanamycin resistance cassette insertion resulted in a significant loss of binding. These findings demonstrate that OapA plays a role in H. influenzae binding to human conjunctival epithelial cells.

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Whitby, Paul W., Thomas W. Seale, Daniel J. Morton, Timothy M. VanWagoner, and Terrence L. Stull. "Characterization of the Haemophilus influenzae tehB gene and its role in virulence." Microbiology 156, no. 4 (April 1, 2010): 1188–200. http://dx.doi.org/10.1099/mic.0.036400-0.

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The Haemophilus influenzae ORF designated HI1275 in the Rd KW20 genomic sequence encodes a putative S-adenosyl methyltransferase with significant similarity to tellurite-resistance determinants (tehB) in other species. While the H. influenzae tehB can complement an Escherichia coli tehB mutation, thus restoring tellurite resistance, its role in H. influenzae is unknown. In a previous study defining the iron and haem modulon of H. influenzae, we showed that transcription of this gene in H. influenzae Rd KW20 increases during growth in iron- and haem-restricted media. Since iron and haem uptake genes, and other known virulence factors, constitute the majority of the iron- and haem-regulated gene set, we postulated that tehB may play a role in nutrient acquisition and/or the virulence of H. influenzae. A tehB mutant was constructed in the H. influenzae type b strain 10810 and was evaluated for growth defects in various supplemented media, as well as for its ability to cause infection in rat models of infection. Deletion of tehB leads to an increase in sensitivity both to tellurite and to the oxidizing agents cumene hydroperoxide, tert-butyl hydroperoxide and hydrogen peroxide. The tehB mutant additionally showed a significantly reduced ability to utilize free haem as well as several haem-containing moieties including haem–human serum albumin, haemoglobin and haemoglobin–haptoglobin. Examination of the regulation kinetics indicated that transcription of tehB was independent of both tellurite exposure and oxidative stress. Paired comparisons of the tehB mutant and the wild-type H. influenzae strain 10810 showed that tehB is required for wild-type levels of infection in rat models of H. influenzae invasive disease. To our knowledge this is the first report of a role for tehB in virulence in any bacterial species. These data demonstrate that H. influenzae tehB plays a role in both resistance to oxidative damage and haem uptake/utilization, protects H. influenzae from tellurite exposure, and is important for virulence of this organism in an animal model of invasive disease.

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43

Jain, Amita, Pradeep Kumar, and Shally Awasthi. "High ampicillin resistance in different biotypes and serotypes of Haemophilus influenzae colonizing the nasopharynx of healthy school-going Indian children." Journal of Medical Microbiology 55, no. 2 (February 1, 2006): 133–37. http://dx.doi.org/10.1099/jmm.0.46249-0.

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Haemophilus influenzae is one of the main causes of otitis media, sinusitis, meningitis, pneumonia and septicaemia in children, and the development of ampicillin resistance in H. influenzae is a cause of serious concern. The aim of the present study was to determine the prevalence of ampicillin resistance in H. influenzae colonizing the nasopharynx of school-going healthy North Indian children, and to compare the distribution of different biotypes and serotype b in this population. A total of 2400 school-going healthy children from 45 rural and 45 urban schools were enrolled. Nasopharyngeal swabs were collected from the children and cultured. H. influenzae was isolated from 1001 (41·7 %) of the 2400 nasopharyngeal swabs collected. All these H. influenzae isolates were biotyped and serotyped, and their antibiotic susceptibility tested. All eight biotypes were present in this population. The most prevalent biotypes were I (19·6 %), II (16·8 %) and III (25·0 %). Of the 1001 isolates, 316 (31·6 %) were H. influenzae type b and 685 (68·4 %) were non-type b H. influenzae, and 22·9 % were resistant to ampicillin, 41·9 % to chloramphenicol, 27·5 % to erythromycin and 67·3 % to co-trimoxazole. Of the 316 H. influenzae type b isolates, 44·0 % were ampicillin resistant, while only 13·1 % non-type b H. influenzae isolates were ampicillin resistant. Of the 229 ampicillin-resistant H. influenzae isolates, 196 (85·6 %) were positive for β-lactamase; 93·4 % (214/229) were biotypes I, II and III, of which 49 % were biotype I, 27·9 % were type II and 16·6 % were type III. Most of the strains belonging to biotypes III–VIII were ampicillin sensitive. Ampicillin resistance is significantly more common in biotype I and serotype b than in other biotypes and serotypes.

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44

&NA;. "H. influenzae antibacterial resistance in Finnish children." Inpharma Weekly &NA;, no. 984 (April 1995): 19. http://dx.doi.org/10.2165/00128413-199509840-00039.

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&NA;. "More investigation of H. influenzae vaccination needed." Inpharma Weekly &NA;, no. 907 (October 1993): 5. http://dx.doi.org/10.2165/00128413-199309070-00008.

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&NA;. "H. influenzae/DTP vaccine combo is practical." Inpharma Weekly &NA;, no. 912 (November 1993): 20. http://dx.doi.org/10.2165/00128413-199309120-00047.

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47

&NA;. "H. influenzae vaccination good value in Spain." Inpharma Weekly &NA;, no. 1179 (March 1999): 8. http://dx.doi.org/10.2165/00128413-199911790-00012.

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TUCKER, MIRIAM E. "Pneumococcal Vaccine Also Works vs. H. influenzae." Pediatric News 40, no. 4 (April 2006): 17. http://dx.doi.org/10.1016/s0031-398x(06)70975-4.

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49

&NA;. "A closer look at H. influenzae vaccines." Inpharma Weekly &NA;, no. 863 (November 1992): 16. http://dx.doi.org/10.2165/00128413-199208630-00037.

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Marwick, Charles. "FDA soon to license H influenzae vaccine." JAMA: The Journal of the American Medical Association 253, no. 9 (March 1, 1985): 1232. http://dx.doi.org/10.1001/jama.1985.03350330022003.

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