scholarly journals In vivo reassortment of influenza viruses.

2014 ◽  
Vol 61 (3) ◽  
Author(s):  
Kinga Urbaniak ◽  
Iwona Markowska-Daniel
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
Influenza Pandemic ◽  
Genetic Material ◽  
Influenza Viruses ◽  
Influenza A Viruses ◽  
Individual Gene ◽  
Different Strains ◽  
The Individual

The genetic material of influenza A virus consists of eight negative-sense RNA segments. Under suitable conditions, the segmented structure of the viral genome allows an exchange of the individual gene segments between different strains, causing formation of new reassorted viruses. For reassortment to occur, co-infection with two or more influenza virus strains is necessary. The reassortment is an important evolutionary mechanism which can result in antigenic shifts that modify host range, pathology, and transmission of the influenza A viruses. In this process, the influenza virus strain with epidemic and/or pandemic potential can be created. Cases of this kind were in 1957 (Asian flu), 1968 (Hong Kong flu) and recently in 2009 (Mexico). Viruses containing genes of avian, swine, and/or human origin are widespread around the world, for example the triple reassortant H1N1 virus causing the 2009 influenza pandemic in 2009 that has become a seasonal virus. The aim of the study is to present the mechanism of reassortment and the results of experimental co-infection with different influenza viruses.

scholarly journals Stochastic processes dominate the within and between host evolution of influenza virus

2017 ◽  
Author(s):  
John T. McCrone ◽  
Robert J. Woods ◽  
Emily T. Martin ◽  
Ryan E. Malosh ◽  
Arnold S. Monto ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Stochastic Processes ◽  
Influenza A ◽  
Evolutionary Dynamics ◽  
Sequence Data ◽  
Influenza A Viruses ◽  
Effective Population ◽  
The Individual ◽  
Host Evolution

AbstractThe global evolutionary dynamics of influenza virus ultimately derive from processes that take place within and between infected individuals. Here we define the dynamics of influenza A virus populations in human hosts through next generation sequencing of 249 specimens from 200 individuals collected over 6290 person-seasons of observation. Because these viruses were collected over 5 seasons from individuals in a prospective community-based cohort, they are broadly representative of natural human infections with seasonal viruses. We used viral sequence data from 35 serially sampled individuals to estimate a within host effective population size of 30-70 and an in vivo mutation rate of 4x10−5 per nucleotide per cellular infectious cycle. These estimates are consistent across several models and robust to the models' underlying assumptions. We also identified 43 epidemiologically linked and genetically validated transmission pairs. Maximum likelihood optimization of multiple transmission models estimates an effective transmission bottleneck of 1-2 distinct genomes. Our data suggest that positive selection of novel viral variants is inefficient at the level of the individual host and that genetic drift and other stochastic processes dominate the within and between host evolution of influenza A viruses.

scholarly journals Influenza: An Emerging and Re-emerging Public Health Threat in Nepal

2018 ◽  
Vol 3 (2) ◽  
pp. 1-2
Author(s):  
Bishnu Prasad Upadhyay
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
Winter Season ◽  
Emerging Infectious Diseases ◽  
Influenza Viruses ◽  
Influenza B ◽  
Influenza A Viruses ◽  
Influenza A H1n1 ◽  
New Variant ◽  
Seasonal Epidemics

Influenza virus type A and B are responsible for seasonal epidemics as well as pandemics in human. Influenza A viruses are further divided into two major groups namely, low pathogenic seasonal influenza (A/H1N1, A/H1N1 pdm09, A/H3N2) and highly pathogenic influenza virus (H5N1, H5N6, H7N9) on the basis of two surface antigens: hemagglutinin (HA) and neuraminidase (NA). Mutations, including substitutions, deletions, and insertions, are one of the most important mechanisms for producing new variant of influenza viruses. During the last 30 years; more than 50 viral threat has been evolved in South-East Asian countriesof them influenza is one of the major emerging and re-emerging infectious diseases of global concern. Similar to tropical and sub-tropical countries of Southeast Asia; circulation of A/H1N1 pdm09, A/H3N2 and influenza B has been circulating throughout the year with the peak during July-November in Nepal. However; the rate of infection transmission reach peak during the post-rain and winter season of Nepal.

scholarly journals Plasticity of the Influenza Virus H5 HA Protein

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Huihui Kong ◽  
David F. Burke ◽  
Tiago Jose da Silva Lopes ◽  
Kosuke Takada ◽  
Masaki Imai ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Mammalian Cells ◽  
Influenza A ◽  
Viral Antigen ◽  
Influenza Viruses ◽  
Influenza A Viruses ◽  
Highly Pathogenic ◽  
Antigenic Properties ◽  
Ha Protein

ABSTRACT Since the emergence of highly pathogenic avian influenza viruses of the H5 subtype, the major viral antigen, hemagglutinin (HA), has undergone constant evolution, resulting in numerous genetic and antigenic (sub)clades. To explore the consequences of amino acid changes at sites that may affect the antigenicity of H5 viruses, we simultaneously mutated 17 amino acid positions of an H5 HA by using a synthetic gene library that, theoretically, encodes all combinations of the 20 amino acids at the 17 positions. All 251 mutant viruses sequenced possessed ≥13 amino acid substitutions in HA, demonstrating that the targeted sites can accommodate a substantial number of mutations. Selection with ferret sera raised against H5 viruses of different clades resulted in the isolation of 39 genotypes. Further analysis of seven variants demonstrated that they were antigenically different from the parental virus and replicated efficiently in mammalian cells. Our data demonstrate the substantial plasticity of the influenza virus H5 HA protein, which may lead to novel antigenic variants. IMPORTANCE The HA protein of influenza A viruses is the major viral antigen. In this study, we simultaneously introduced mutations at 17 amino acid positions of an H5 HA expected to affect antigenicity. Viruses with ≥13 amino acid changes in HA were viable, and some had altered antigenic properties. H5 HA can therefore accommodate many mutations in regions that affect antigenicity. The substantial plasticity of H5 HA may facilitate the emergence of novel antigenic variants.

scholarly journals Broadly Reactive H2 Hemagglutinin Vaccines Elicit Cross-Reactive Antibodies in Ferrets Preimmune to Seasonal Influenza A Viruses

mSphere ◽  
2021 ◽  
Vol 6 (2) ◽  
Author(s):  
Z. Beau Reneer ◽  
Amanda L. Skarlupka ◽  
Parker J. Jamieson ◽  
Ted M. Ross
Keyword(s):  
Influenza Virus ◽  
Immune Responses ◽  
Recombinant Proteins ◽  
Human Population ◽  
Influenza A ◽  
Seasonal Influenza ◽  
Influenza Viruses ◽  
Wild Type ◽  
Influenza A Viruses ◽  
Global Pandemic

ABSTRACT Influenza vaccines have traditionally been tested in naive mice and ferrets. However, humans are first exposed to influenza viruses within the first few years of their lives. Therefore, there is a pressing need to test influenza virus vaccines in animal models that have been previously exposed to influenza viruses before being vaccinated. In this study, previously described H2 computationally optimized broadly reactive antigen (COBRA) hemagglutinin (HA) vaccines (Z1 and Z5) were tested in influenza virus “preimmune” ferret models. Ferrets were infected with historical, seasonal influenza viruses to establish preimmunity. These preimmune ferrets were then vaccinated with either COBRA H2 HA recombinant proteins or wild-type H2 HA recombinant proteins in a prime-boost regimen. A set of naive preimmune or nonpreimmune ferrets were also vaccinated to control for the effects of the multiple different preimmunities. All of the ferrets were then challenged with a swine H2N3 influenza virus. Ferrets with preexisting immune responses influenced recombinant H2 HA-elicited antibodies following vaccination, as measured by hemagglutination inhibition (HAI) and classical neutralization assays. Having both H3N2 and H1N1 immunological memory regardless of the order of exposure significantly decreased viral nasal wash titers and completely protected all ferrets from both morbidity and mortality, including the mock-vaccinated ferrets in the group. While the vast majority of the preimmune ferrets were protected from both morbidity and mortality across all of the different preimmunities, the Z1 COBRA HA-vaccinated ferrets had significantly higher antibody titers and recognized the highest number of H2 influenza viruses in a classical neutralization assay compared to the other H2 HA vaccines. IMPORTANCE H1N1 and H3N2 influenza viruses have cocirculated in the human population since 1977. Nearly every human alive today has antibodies and memory B and T cells against these two subtypes of influenza viruses. H2N2 influenza viruses caused the 1957 global pandemic and people born after 1968 have never been exposed to H2 influenza viruses. It is quite likely that a future H2 influenza virus could transmit within the human population and start a new global pandemic, since the majority of people alive today are immunologically naive to viruses of this subtype. Therefore, an effective vaccine for H2 influenza viruses should be tested in an animal model with previous exposure to influenza viruses that have circulated in humans. Ferrets were infected with historical influenza A viruses to more accurately mimic the immune responses in people who have preexisting immune responses to seasonal influenza viruses. In this study, preimmune ferrets were vaccinated with wild-type (WT) and COBRA H2 recombinant HA proteins in order to examine the effects that preexisting immunity to seasonal human influenza viruses have on the elicitation of broadly cross-reactive antibodies from heterologous vaccination.

scholarly journals Influenza A Virus Inhibits RSV Infection via a Two-Wave Expression of IFIT Proteins

Viruses ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1171
Author(s):  
Yaron Drori ◽  
Jasmine Jacob-Hirsch ◽  
Rakefet Pando ◽  
Aharona Glatman-Freedman ◽  
Nehemya Friedman ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Influenza Viruses ◽  
Mass Spectrometry Analysis ◽  
Influenza A Viruses ◽  
Rsv Infection ◽  
Syncytial Virus ◽  
Mouse Lungs

Influenza viruses and respiratory syncytial virus (RSV) are respiratory viruses that primarily circulate worldwide during the autumn and winter seasons. Seasonal surveillance has shown that RSV infection generally precedes influenza. However, in the last four winter seasons (2016–2020) an overlap of the morbidity peaks of both viruses was observed in Israel, and was paralleled by significantly lower RSV infection rates. To investigate whether the influenza A virus inhibits RSV, human cervical carcinoma (HEp2) cells or mice were co-infected with influenza A and RSV. Influenza A inhibited RSV growth, both in vitro and in vivo. Mass spectrometry analysis of mouse lungs infected with influenza A identified a two-wave pattern of protein expression upregulation, which included members of the interferon-induced protein with the tetratricopeptide (IFITs) family. Interestingly, in the second wave, influenza A viruses were no longer detectable in mouse lungs. In addition, knockdown and overexpression of IFITs in HEp2 cells affected RSV multiplicity. In conclusion, influenza A infection inhibits RSV infectivity via upregulation of IFIT proteins in a two-wave modality. Understanding the immune system involvement in the interaction between influenza A and RSV viruses will contribute to the development of future treatment strategies against these viruses.

scholarly journals International Laboratory Comparison of Influenza Microneutralization Assays for A(H1N1)pdm09, A(H3N2), and A(H5N1) Influenza Viruses by CONSISE

2015 ◽  
Vol 22 (8) ◽  
pp. 957-964 ◽  
Author(s):  
Karen L. Laurie ◽  
Othmar G. Engelhardt ◽  
John Wood ◽  
Alan Heath ◽  
Jacqueline M. Katz ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Incubation Time ◽  
Influenza A ◽  
Influenza Viruses ◽  
Enzyme Linked Immunosorbent Assay ◽  
Influenza A Viruses ◽  
H5n1 Influenza ◽  
The World ◽  
International Laboratory ◽  
The Impact

ABSTRACTThe microneutralization assay is commonly used to detect antibodies to influenza virus, and multiple protocols are used worldwide. These protocols differ in the incubation time of the assay as well as in the order of specific steps, and even within protocols there are often further adjustments in individual laboratories. The impact these protocol variations have on influenza serology data is unclear. Thus, a laboratory comparison of the 2-day enzyme-linked immunosorbent assay (ELISA) and 3-day hemagglutination (HA) microneutralization (MN) protocols, using A(H1N1)pdm09, A(H3N2), and A(H5N1) viruses, was performed by the CONSISE Laboratory Working Group. Individual laboratories performed both assay protocols, on multiple occasions, using different serum panels. Thirteen laboratories from around the world participated. Within each laboratory, serum sample titers for the different assay protocols were compared between assays to determine the sensitivity of each assay and were compared between replicates to assess the reproducibility of each protocol for each laboratory. There was good correlation of the results obtained using the two assay protocols in most laboratories, indicating that these assays may be interchangeable for detecting antibodies to the influenza A viruses included in this study. Importantly, participating laboratories have aligned their methodologies to the CONSISE consensus 2-day ELISA and 3-day HA MN assay protocols to enable better correlation of these assays in the future.

scholarly journals Divergent Human-Origin Influenza Viruses Detected in Australian Swine Populations

2018 ◽  
Vol 92 (16) ◽  
Author(s):  
Frank Y. K. Wong ◽  
Celeste Donato ◽  
Yi-Mo Deng ◽  
Don Teng ◽  
Naomi Komadina ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
Swine Influenza ◽  
Influenza Viruses ◽  
Antigenic Drift ◽  
Human Origin ◽  
Human Influenza ◽  
Influenza A Viruses ◽  
Data Set ◽  
Antigenic Properties

ABSTRACTGlobal swine populations infected with influenza A viruses pose a persistent pandemic risk. With the exception of a few countries, our understanding of the genetic diversity of swine influenza viruses is limited, hampering control measures and pandemic risk assessment. Here we report the genomic characteristics and evolutionary history of influenza A viruses isolated in Australia from 2012 to 2016 from two geographically isolated swine populations in the states of Queensland and Western Australia. Phylogenetic analysis with an expansive human and swine influenza virus data set comprising >40,000 sequences sampled globally revealed evidence of the pervasive introduction and long-term establishment of gene segments derived from several human influenza viruses of past seasons, including the H1N1/1977, H1N1/1995, H3N2/1968, and H3N2/2003, and the H1N1 2009 pandemic (H1N1pdm09) influenza A viruses, and a genotype that contained gene segments derived from the past three pandemics (1968, reemerged 1977, and 2009). Of the six human-derived gene lineages, only one, comprising two viruses isolated in Queensland during 2012, was closely related to swine viruses detected from other regions, indicating a previously undetected circulation of Australian swine lineages for approximately 3 to 44 years. Although the date of introduction of these lineages into Australian swine populations could not be accurately ascertained, we found evidence of sustained transmission of two lineages in swine from 2012 to 2016. The continued detection of human-origin influenza virus lineages in swine over several decades with little or unpredictable antigenic drift indicates that isolated swine populations can act as antigenic archives of human influenza viruses, raising the risk of reemergence in humans when sufficient susceptible populations arise.IMPORTANCEWe describe the evolutionary origins and antigenic properties of influenza A viruses isolated from two separate Australian swine populations from 2012 to 2016, showing that these viruses are distinct from each other and from those isolated from swine globally. Whole-genome sequencing of virus isolates revealed a high genotypic diversity that had been generated exclusively through the introduction and establishment of human influenza viruses that circulated in past seasons. We detected six reassortants with gene segments derived from human H1N1/H1N1pdm09 and various human H3N2 viruses that circulated during various periods since 1968. We also found that these swine viruses were not related to swine viruses collected elsewhere, indicating independent circulation. The detection of unique lineages and genotypes in Australia suggests that isolated swine populations that are sufficiently large can sustain influenza virus for extensive periods; we show direct evidence of a sustained transmission for at least 4 years between 2012 and 2016.

scholarly journals Role of Sialic Acid Binding Specificity of the 1918 Influenza Virus Hemagglutinin Protein in Virulence and Pathogenesis for Mice

2009 ◽  
Vol 83 (8) ◽  
pp. 3754-3761 ◽  
Author(s):  
Li Qi ◽  
John C. Kash ◽  
Vivien G. Dugan ◽  
Ruixue Wang ◽  
Guozhong Jin ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Sialic Acid ◽  
Influenza A ◽  
Influenza Pandemic ◽  
Binding Specificity ◽  
Influenza Viruses ◽  
Virulence Determinants ◽  
Sialic Acid Binding ◽  
1918 Influenza

ABSTRACT The 1918 influenza pandemic caused more than 40 million deaths and likely resulted from the introduction and adaptation of a novel avian-like virus. Influenza A virus hemagglutinins are important in host switching and virulence. Avian-adapted influenza virus hemagglutinins bind sialic acid receptors linked via α2-3 glycosidic bonds, while human-adapted hemagglutinins bind α2-6 receptors. Sequence analysis of 1918 isolates showed hemagglutinin genes with α2-6 or mixed α2-6/α2-3 binding. To characterize the role of the sialic acid binding specificity of the 1918 hemagglutinin, we evaluated in mice chimeric influenza viruses expressing wild-type and mutant hemagglutinin genes from avian and 1918 strains with differing receptor specificities. Viruses expressing 1918 hemagglutinin possessing either α2-6, α2-3, or α2-3/α2-6 sialic acid specificity were fatal to mice, with similar pathology and cellular tropism. Changing α2-3 to α2-6 binding specificity did not increase the lethality of an avian-adapted hemagglutinin. Thus, the 1918 hemagglutinin contains murine virulence determinants independent of receptor binding specificity.

The influenza virus PB1-F2 protein has interferon antagonistic activity

2011 ◽  
Vol 392 (12) ◽  
pp. 1135-1144 ◽  
Author(s):  
Sabine E. Dudek ◽  
Ludmilla Wixler ◽  
Carolin Nordhoff ◽  
Alexandra Nordmann ◽  
Darisuren Anhlan ◽  
...  
Keyword(s):  
Influenza A ◽  
Molecular Mechanisms ◽  
Nonstructural Protein ◽  
Gene Segment ◽  
Antagonistic Activity ◽  
Influenza Viruses ◽  
Type I ◽  
Influenza A Viruses ◽  
Reading Frame

Abstract PB1-F2 is a nonstructural protein of influenza viruses encoded by the PB1 gene segment from a +1 open reading frame. It has been shown that PB1-F2 contributes to viral pathogenicity, although the underlying mechanisms are still unclear. Induction of type I interferon (IFN) and the innate immune response are the first line of defense against viral infection. Here we show that influenza A viruses (IAVs) lacking the PB1-F2 protein induce an enhanced expression of IFN-β and IFN-stimulated genes in infected epithelial cells. Studying molecular mechanisms underlying the PB1-F2-mediated IFN antagonistic activity showed that PB1-F2 interferes with the RIG-I/MAVS protein complex thereby inhibiting the activation of the downstream transcription factor IFN regulatory factor 3. These findings were also reflected in in vivo studies demonstrating that infection with PR8 wild-type (wt) virus resulted in higher lung titers and a more severe onset of disease compared with infection with its PB1-F2-deficient counterpart. Accordingly, a much more pronounced infiltration of lungs with immune cells was detected in mice infected with the PB1-F2 wt virus. In summary, we demonstrate that the PB1-F2 protein of IAVs exhibits a type I IFN-antagonistic function by interfering with the RIG-I/MAVS complex, which contributes to an enhanced pathogenicity in vivo.

scholarly journals Heterosubtypic Protection Conferred by the Human Monoclonal Antibody PN-SIA28 against Influenza A Virus Lethal Infections in Mice

2015 ◽  
Vol 59 (5) ◽  
pp. 2647-2653 ◽  
Author(s):  
Miguel Retamal ◽  
Yacine Abed ◽  
Chantal Rhéaume ◽  
Francesca Cappelletti ◽  
Nicola Clementi ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Body Weight ◽  
Influenza Virus ◽  
Influenza A ◽  
Human Monoclonal Antibody ◽  
Influenza A Viruses ◽  
Virus Challenge ◽  
Influenza A H1n1

ABSTRACTPN-SIA28 is a human monoclonal antibody (Hu-MAb) targeting highly conserved epitopes within the stem portion of the influenza virus hemagglutinin (HA) (N. Clementi, et al, PLoS One 6:e28001, 2011,http://dx.doi.org/10.1371/journal.pone.0028001). Previousin vitrostudies demonstrated PN-SIA28 neutralizing activities against phylogenetically divergent influenza A subtypes. In this study, the protective activity of PN-SIA28 was evaluated in mice inoculated with lethal influenza A/WSN/33 (H1N1), A/Quebec/144147/09 (H1N1)pdm09, and A/Victoria/3/75 (H3N2) viruses. At 24 h postinoculation (p.i.), animals received PN-SIA28 intraperitoneally (1 or 10 mg/kg of body weight) or 10 mg/kg of unrelated Hu-MAb (mock). Body weight loss and mortality rate (MR) were recorded for 14 days postinfection (p.i.). Lung viral titers (LVT) were determined at day 5 p.i. In A/WSN/33 (H1N1)-infected groups, all untreated and mock-receiving mice died, whereas MRs of 87.5% and 25% were observed in mice that received PN-SIA28 1 and 10 mg/kg, respectively. In influenza A(H1N1) pdm09-infected groups, an MR of 75% was recorded for untreated and mock-treated groups, whereas the PN-SIA28 1-mg/kg and 10-mg/kg groups had rates of 62.5% and 0%, respectively. In A/Victoria/3/75 (H3N2)-infected animals, untreated and mock-treated animals had MRs of 37.5% and 25%, respectively, and no mortalities were recorded after PN-SIA28 treatments. Accordingly, PN-SIA28 treatments significantly reduced weight losses and resulted in a ≥1-log reduction in LVT compared to the control in all infection groups. This study confirms that antibodies targeting highly conserved epitopes in the influenza HA stem region, like PN-SIA28, not only neutralize influenza A viruses of clinically relevant subtypesin vitrobut also, more importantly, protect from a lethal influenza virus challengein vivo.

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