The Multibasic Cleavage Site of the Hemagglutinin of Highly Pathogenic A/Vietnam/1203/2004 (H5N1) Avian Influenza Virus Acts as a Virulence Factor in a Host-Specific Manner in Mammals

Suguitan, Amorsolo L.; Matsuoka, Yumiko; Lau, Yuk-Fai; Santos, Celia; Vogel, Leatrice; Cheng, Lily; Orandle, Marlene S.; Subbarao, Kanta

doi:10.1128/jvi.05546-11

Cited by 90 publications

(79 citation statements)

References 55 publications

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“…In this study, we did not examine the effect of inoculum volume on infection with seasonal human influenza viruses or avian influenza viruses that differ significantly in their sialic acid receptor preferences. However, in a separate study, we observed that a highly pathogenic H5N1 influenza virus administered in 0.2 ml caused only mild clinical disease in ferrets (unpublished data), while the same amount of virus administered in an inoculum volume of 0.5 ml caused neurological disease, including hind limb paresis (38). Taken together with the findings from the current study, it is likely that the animals that received 0.2 ml of the H5N1 virus had milder clinical disease than the animals that received the 0.5-ml inoculum because the smaller volume did not efficiently infect the LRT, where the ␣2,3 SA receptors predominate.…”

Section: Discussionmentioning

confidence: 99%

Severity of Clinical Disease and Pathology in Ferrets Experimentally Infected with Influenza Viruses Is Influenced by Inoculum Volume

Moore

Lamirande

Paskel

et al. 2014

J Virol

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Ferrets are a valuable model for influenza virus pathogenesis, virus transmission, and antiviral therapy studies. However, the contributions of the volume of inoculum administered and the ferret's respiratory tract anatomy to disease outcome have not been explored. We noted variations in clinical disease outcomes and the volume of inoculum administered and investigated these differences by administering two influenza viruses (A/California/07/2009 [H1N1 pandemic] and A/Minnesota/11/2010 [H3N2 variant]) to ferrets intranasally at a dose of 10 6 50% tissue culture infective doses in a range of inoculum volumes (0.2, 0.5, or 1.0 ml) and followed viral replication, clinical disease, and pathology over 6 days. Clinical illness and respiratory tract pathology were the most severe and most consistent when the viruses were administered in a volume of 1.0 ml. Using a modified micro-computed tomography imaging method and examining gross specimens, we found that the right main-stem bronchus was consistently larger in diameter than the left main-stem bronchus, though the latter was longer and straighter. These anatomic features likely influence the distribution of the inoculum in the lower respiratory tract. A 1.0-ml volume of inoculum is optimal for delivery of virus to the lower respiratory tract of ferrets, particularly when evaluation of clinical disease is desired. Furthermore, we highlight important anatomical features of the ferret lung that influence the kinetics of viral replication, clinical disease severity, and lung pathology. IMPORTANCEFerrets are a valuable model for influenza virus pathogenesis, virus transmission, and antiviral therapy studies. Clinical disease in ferrets is an important parameter in evaluating the virulence of novel influenza viruses, and findings are extrapolated to virulence in humans. Therefore, it is highly desirable that the data from different laboratories be accurate and reproducible. We have found that, even when the same virus was administered at similar doses, different investigators reported a range of clinical disease outcomes, from asymptomatic infection to severe weight loss, ocular and nasal discharge, sneezing, and lethargy. We found that a wide range of inoculum volumes was used to experimentally infect ferrets, and we sought to determine whether the variations in disease outcome were the result of the volume of inoculum administered. These data highlight some less explored features of the model, methods of experimental infection, and clinical disease outcomes in a research setting.

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Section: Discussionmentioning

confidence: 99%

Severity of Clinical Disease and Pathology in Ferrets Experimentally Infected with Influenza Viruses Is Influenced by Inoculum Volume

Moore

Lamirande

Paskel

et al. 2014

J Virol

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“…122 However, the HPAI H5N1 virus, which does have a multibasic cleavage site, can be lethal for mice and ferrets in which it induces increased cytokine levels and virus titers and results in systemic infection. 136 This does not occur in pigs, 82 which may reflect a difference in tissue proteases in this species. The HA from the 1918 human pandemic H1N1virus, which does not have a multibasic cleavage site but still appears to be highly cleavable, also confers increased virulence to reassortants as reflected in increased virus titers and inflammation in mice and human airway cells.…”

Section: Hemagglutininmentioning

confidence: 99%

Influenza A Virus Infections in Swine

Janke

2013

Vet Pathol

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Influenza has been recognized as a respiratory disease in swine since its first appearance concurrent with the 1918 ''Spanish flu'' human pandemic. All influenza viruses of significance in swine are type A, subtype H1N1, H1N2, or H3N2 viruses. Influenza viruses infect epithelial cells lining the surface of the respiratory tract, inducing prominent necrotizing bronchitis and bronchiolitis and variable interstitial pneumonia. Cell death is due to direct virus infection and to insult directed by leukocytes and cytokines of the innate immune system. The most virulent viruses consistently express the following characteristics of infection: (1) higher or more prolonged virus replication, (2) excessive cytokine induction, and (3) replication in the lower respiratory tract. Nearly all the viral proteins contribute to virulence. Pigs are susceptible to infection with both human and avian viruses, which often results in gene reassortment between these viruses and endemic swine viruses. The receptors on the epithelial cells lining the respiratory tract are major determinants of infection by influenza viruses from other hosts. The polymerases, especially PB2, also influence cross-species infection. Methods of diagnosis and characterization of influenza viruses that infect swine have improved over the years, driven both by the availability of new technologies and by the necessity of keeping up with changes in the virus. Testing of oral fluids from pigs for virus and antibody is a recent development that allows efficient sampling of large numbers of animals.Keywords influenza virus, swine, pathogenesis, cytokines, apoptosis, virulence, cross-species infection, hemagglutinin, receptors, polymerases, diagnosisThe evolution and epidemiology of influenza A virus (IAV) infections in swine have been integrally tied to the segmented nature of the genome of the virus, which facilitates gene reassortment, and to the adaptability of these genes through mutation, which sometimes facilitates replication in a new host. 8,19,77,85,89 Influenza was first recognized as a respiratory disease entity in swine during the 1918 human Spanish flu pandemic. 67 The virus was not isolated until 1931, when nasal discharge from pigs was inoculated into ferrets and subsequently into embryonated chicken eggs. 129 In 1933, a similar virus was recovered from humans with this technique. 131 The viruses were essentially identical and served as the prototype for type A subtype H1N1 influenza viruses.All influenza viruses of significance that infect swine are type A viruses, defined by the highly conserved internal nucleoproteins and matrix proteins. Influenza A virus subtypes are based on the external hemagglutinin (HA) and neuraminidase (NA) proteins. The predominant viruses in swine populations in different parts of the world may have genes of different origin, even though the subtypes may be similar. 10,73,171 The original classic H1N1 swine influenza virus, which remained the predominant influenza virus in North American swine populations for nearl...

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“…For example, the HA protein of HPAIV plays crucial roles in systemic replication and lethal infection in chickens (24) and mammals (25,26). Mutations in the M1 protein also affect the virulence of H5N1 viruses in mice (27).…”

Section: Discussionmentioning

confidence: 99%

Molecular Determinants of Virulence and Stability of a Reporter-Expressing H5N1 Influenza A Virus

Zhao

Fukuyama

Yamada

et al. 2015

J Virol

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We previously reported that an H5N1 virus carrying the Venus reporter gene, which was inserted into the NS gene segment from the A/Puerto Rico/8/1934(H1N1) virus (Venus-H5N1 virus), became more lethal to mice, and the reporter gene was stably maintained after mouse adaptation compared with the wild-type Venus-H5N1 (WT-Venus-H5N1) virus. However, the basis for this difference in virulence and Venus stability was unclear. Here, we investigated the molecular determinants behind this virulence and reporter stability by comparing WT-Venus-H5N1 virus with a mouse-adapted Venus-H5N1 (MA-Venus-H5N1) virus. To determine the genetic basis for these differences, we used reverse genetics to generate a series of reassortants of these two viruses. We found that reassortants with PB2 from MA-Venus-H5N1 (MA-PB2), MA-PA, or MA-NS expressed Venus more stably than did WT-Venus-H5N1 virus. We also found that a single mutation in PB2 (V25A) or in PA (R443K) increased the virulence of the WT-Venus-H5N1 virus in mice and that the presence of both of these mutations substantially enhanced the pathogenicity of the virus. Our results suggest roles for PB2 and PA in the stable maintenance of a foreign protein as an NS1 fusion protein in influenza A virus. IMPORTANCEThe ability to visualize influenza viruses has far-reaching benefits in influenza virus research. Previously, we reported that an H5N1 virus bearing the Venus reporter gene became more pathogenic to mice and that its reporter gene was more highly expressed and more stably maintained after mouse adaptation. Here, we investigated the molecular determinants behind this enhanced virulence and reporter stability. We found that mutations in PB2 (V25A) and PA (R443K) play crucial roles in the stable maintenance of a foreign protein as an NS1 fusion protein in influenza A virus and in the virulence of influenza virus in mice. Our findings further our knowledge of the pathogenicity of influenza virus in mammals and will help advance influenza virusrelated live-imaging studies in vitro and in vivo.

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The Multibasic Cleavage Site of the Hemagglutinin of Highly Pathogenic A/Vietnam/1203/2004 (H5N1) Avian Influenza Virus Acts as a Virulence Factor in a Host-Specific Manner in Mammals

Cited by 90 publications

References 55 publications

Severity of Clinical Disease and Pathology in Ferrets Experimentally Infected with Influenza Viruses Is Influenced by Inoculum Volume

Severity of Clinical Disease and Pathology in Ferrets Experimentally Infected with Influenza Viruses Is Influenced by Inoculum Volume

Influenza A Virus Infections in Swine

Molecular Determinants of Virulence and Stability of a Reporter-Expressing H5N1 Influenza A Virus

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