scholarly journals ANTIGENIC VARIANTS OF INFLUENZA A VIRUS (PR8 STRAIN)

1956 ◽  
Vol 103 (4) ◽  
pp. 413-424 ◽  
Author(s):  
Paul Gerber ◽  
Dorothy Hamre ◽  
Clayton G. Loosli
Keyword(s):  
Influenza A ◽  
Serial Passage ◽  
Influenza Viruses ◽  
Progressive Reduction ◽  
In Ovo ◽  
Antibody Absorption ◽  
Antigenic Properties ◽  
Successive Generations ◽  
Lethal Doses ◽  
Selective Environment

Four successive generations of antigenic variants of influenza PR8-S virus, each derived from the previous one by serial passage in the lungs of mice immunized with the homologous agent, were compared with the original parent PR8-S virus with respect to their serological and immunological character. It was demonstrated by means of H.I., complement-fixation and in ovo-neutralization tests that the variants exhibited a progressively decreasing reactivity with the parent PR8-S antiserum while retaining the ability to elicit antibody to PR8-S influenza virus and to their respective predecessors. Accompanying these changes was a progressive reduction in antigenicity without any significant changes in pathogenicity for mice. Experimental evidence was presented which indicates that the serological changes observed with the variants are not related to the P-Q phenomenon. Antibody absorption tests showed that the variants share antigens with PR8-S virus but differ from it by the presence of specific antigenic components; these increase in quantity with each successive variant while the amount of related antigens shows a progressive decrease. The importance of evaluating the significance of antigenic changes of influenza viruses with active immunity tests was emphasized by the fact that PR8-S vaccine protected mice against fatal infection with lethal doses of the variant strains although the latter had a progressively decreasing serological reactivity with PR8-S antiserum. The inheritable character of the new antigenic properties of the variant strains was demonstrated by their persistence in the absence of thea selective environment following 18 to 24 serial intranasal passages with large inocula in normal mice and following limiting dilution passage in fertile eggs.

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 Bayesian inference of antigenic and non-antigenic variables from haemagglutination inhibition assays for influenza surveillance

2018 ◽  
Vol 5 (7) ◽  
pp. 180113
Author(s):  
Emmanuel S. Adabor ◽  
Wilfred Ndifon
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
Bayesian Method ◽  
Haemagglutination Inhibition ◽  
Virus Evolution ◽  
Influenza Viruses ◽  
Influenza Surveillance ◽  
Antigenic Properties ◽  
Analytical Work

Haemagglutination inhibition (HI) assays are typically used for comparing and characterizing influenza viruses. Data obtained from the assays (titres) are used quantitatively to determine antigenic differences between influenza strains. However, the use of these titres has been criticized as they sometimes fail to capture accurate antigenic differences between strains. Our previous analytical work revealed how antigenic and non-antigenic variables contribute to the titres. Building on this previous work, we have developed a Bayesian method for decoupling antigenic and non-antigenic contributions to the titres in this paper. We apply this method to a compendium of HI titres of influenza A (H3N2) viruses curated from 1968 to 2016. Remarkably, the results of this fit indicate that the non-antigenic variable, which is inversely correlated with viral avidity for the red blood cells used in HI assays, oscillates during the course of influenza virus evolution, with a period that corresponds roughly to the timescale on which antigenic variants replace each other. Together, the results suggest that the new Bayesian method is applicable to the analysis of long-term dynamics of both antigenic and non-antigenic properties of influenza virus.

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 Virological, epidemiological, clinic, and molecular genetic features of the influenza epidemic in 2015-2016: prevailing of the influenza A(H1N1)09 pdm virus in Russia and countries of the Northern hemisphere

2016 ◽  
Vol 61 (4) ◽  
pp. 159-166
Author(s):  
D. K. Lvov ◽  
E. I. Burtseva ◽  
L. V. Kolobukhina ◽  
I. T. Fedyakina ◽  
E. S. Kirillova ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Russian Federation ◽  
Influenza A ◽  
Influenza Viruses ◽  
High Rate ◽  
Research Centre ◽  
Sequencing Data ◽  
Influenza A H1n1 ◽  
Antigenic Properties ◽  
The Russian Federation

This work describes the specific features of the influenza virus circulating in the period from October 2015 to March 2016 in 10 cities of Russia, the basic laboratories of CEEI at the D.I. Ivanovsky Institute of Virology “Federal Research Centre of Epidemilogy and Microbiology named after the honorary academician N.F. Gamaleya” of the Ministry of Health of the Russian Federation. The increase in the morbidity caused by influenza viruses was detected in January-February 2016. The duration of the morbidity peak was 4-5 weeks. The most vulnerable group included children at the age from 3 to 6; a high rate of hospitalization was also detected among people at the age of 15-64 (65%). In clinic symptoms there were middle and severe forms with high frequency of hospitalization as compared with the season of 2009-2010, but much higher in comparison with the season of 2014-2015. Some of the hospitalized patients had virus pneumonias, half of which were bilateral. Among these patients, 10% were children; 30%, adults. The mortality in the intensive care unit of the hospital was 46%. Almost all lethal cases were among unvaccinated patients in the case of late hospitalization and without early antiviral therapy. The predominance of the influenza A(H1N1)09pdm virus both in the Russian Federation and the major part of the countries in the Northern hemisphere was noted. The results of the study of the antigenic properties of influenza strains of A(H1N1)pdm09 virus did not reveal any differences with respect to the vaccine virus. The sequencing data showed the amino acid substitutions in hemagglutinin (receptor binding and Sa sites) and in genes encoding internal proteins (PA, NP, M1, NS1). Strains were sensitive to oseltamivir and zanamivir and maintained resistance to rimantadine. The participation of non-influenza ARI viruses was comparable to that in preliminary epidemic seasons.

scholarly journals PERSISTENT ANTIGENIC VARIATION OF INFLUENZA A VIRUSES AFTER INCOMPLETE NEUTRALIZATION IN OVO WITH HETEROLOGOUS IMMUNE SERUM

1950 ◽  
Vol 92 (5) ◽  
pp. 441-462 ◽  
Author(s):  
Italo Archetti ◽  
Frank L. Horsfall
Keyword(s):  
Influenza A ◽  
Antigenic Variation ◽  
Laboratory Strain ◽  
Serial Passage ◽  
Immune Serum ◽  
Influenza A Viruses ◽  
In Ovo ◽  
Cross Neutralization ◽  
Different Strains ◽  
At Will

Antigenic variants of influenza A virus strains emerge on serial passage in ovo in the presence of immune serum against different but related strains. An old laboratory strain (PR8) which had been through hundreds of animal passages was as readily modified by this procedure as recently recovered strains. Such variants apparently can be obtained at will and show antigenic patterns which are reproducible and appear to be predictable in terms of the immune serum used for their selection. Variant strains retain their new antigenic patterns on serial passage in ovo in the absence of immune serum. Limited serial passage in ovo of strains in the absence of immune serum did not result in the emergence of antigenic variants. Similarly, serial passages of strains in ovo in the presence of immune serum against widely different strains, which failed to show significant cross-neutralization, did not lead to the appearance of antigenic variants.

scholarly journals Evolution of influenza viruses based on sensitivity to temperature of replication

2019 ◽  
pp. 47-55
Author(s):  
N. V. Larionova ◽  
I. V. Kiseleva ◽  
L. G. Rudenko
Keyword(s):  
Temperature Sensitivity ◽  
Influenza A ◽  
Cold Resistance ◽  
Biological Properties ◽  
Influenza Viruses ◽  
Temperature Sensitive ◽  
Important Indicator ◽  
Antigenic Properties ◽  
Optimal Values ◽  
Incubation Temperatures

Introduction. The assessment of the ability of influenza viruses to replication at temperature conditions beyond optimal values approaches us to understanding the laws of their evolutionary variability. The temperature range for the reproduction of epidemic viruses is also an important indicator for choosing a rational strategy for producing attenuated reassortants for a live influenza vaccine.The purpose of the study is a retrospective analysis of the biological properties of influenza viruses from various pandemic and epidemic cycles based on their ability to replicate at temperatures beyond optimal values.Materials and methods. We studied 234 strains of human influenza A and B viruses that caused epidemics in the 20th – 21st centuries. The infectious activity of viruses at different incubation temperatures was determined in developing chicken embryos. The temperature sensitivity and cold resistance of viruses replication were estimated as a difference of infectious titers at the optimum and raised or lowered incubation temperatures.Results. Data from a retrospective study indicate that the range of sensitivity to replication temperature during the natural drift of influenza A and B pathogens is subject to regular variability that has a cyclic character.Discussion. To assess the evolution and epidemic potential of influenza viruses, it is important not only to register a change in their antigenic properties but also to take into account the temperature sensitivity of the reproduction. Both of these properties contribute to the manifestation of the virulence of the virus. Prolonged circulation of temperature-sensitive viruses can be a prerequisite for the appearance of a radically new drift variant and even shift.Conclusion. The analysis of the variability of the biological properties of influenza viruses approaches to the comprehension of possible ways of their evolution, that contributes to the development of rational methods for preventing the spread of viruses and the incidence caused by them.

scholarly journals Antibodies directed towards neuraminidase N1 control disease in a mouse model of influenza

2017 ◽  
pp. JVI.01584-17 ◽  
Author(s):  
E.R. Job ◽  
M. Schotsaert ◽  
L.I. Ibañez ◽  
A. Smet ◽  
T. Ysenbaert ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Antiviral Activity ◽  
Influenza A ◽  
Conformational Epitope ◽  
Influenza Viruses ◽  
Lethal Challenge ◽  
H5n1 Influenza ◽  
Antigenic Properties

There is increasing evidence to suggest that antibodies directed towards influenza A virus (IAV) neuraminidase (NA) are an important correlate of protection against influenza in humans. Moreover, the potential of NA-specific antibodies to provide broader protection than conventional hemagglutinin (HA) antibodies has been recognized. Herein, we describe the isolation of two monoclonal antibodies, N1-7D3 and N1-C4, directed towards the N1 NA. N1-7D3 binds to a conserved linear epitope in the membrane distal, carboxy-terminal part of the NA and reacted with the NA of seasonal H1N1 isolates ranging from 1977 till 2007 the 2009 H1N1pdm virus as well as A/Vietnam/1194/04 (H5N1). However, N1-7D3 lacked NA inhibition (NI) activity and the ability to protect BALB/c mice against a lethal challenge with a range of H1N1 viruses. Conversely, N1-C4 bound to a conformational epitope that is conserved between two influenza subtypes, the 2009 H1N1pdm and H5N1 IAV and displayed potentin vitroantiviral activity mediating both NI and plaque size-reduction. Moreover, N1-C4 could provide heterosubtypic protection in BALB/c mice against a lethal challenge with 2009 H1N1pdm or H5N1 virus. Glutamic acid residue 311 in the NA was found to be critical for the NA binding and antiviral activity of monoclonal antibody N1-C4. Our data provide further evidence on cross-protective epitopes within the N1 subtype and highlight the potential of NA as an important target for vaccine and therapeutic approaches.ImportanceInfluenza remains a world-wide burden to public health. As such the development of new and novel vaccines and therapeutics against influenza virus is crucial. Human challenge studies have recently highlighted the importance of antibodies directed towards the viral neuraminidase (NA) as an important correlate of reduced influenza-associated disease severity. Furthermore, there is evidence that anti-NA antibodies can provide broader protection than antibodies towards the viral hemagglutinin. Here we describe the isolation and detailed characterization of two N1 NA-specific monoclonal antibodies. One of these monoclonal antibodies broadly binds N1 type NAs and the second one displays NAI, in vitro and in vivo anti-viral activity against 2009 H1N1pdm and H5N1 influenza viruses. These two new anti-NA antibodies contribute to our understanding of the antigenic properties and protective potential of the influenza NA antigen.

scholarly journals Characterization of a new influenza virus type D

2016 ◽  
Vol 72 (9) ◽  
pp. 531-535
Author(s):  
Iwona Markowska-Daniel ◽  
Marcin Mickiewicz ◽  
Lucjan Witkowski ◽  
Jerzy Kita
Keyword(s):  
Influenza Virus ◽  
Receptor Binding ◽  
Influenza A ◽  
Evolutionary Relationship ◽  
Influenza Viruses ◽  
Virus Protein ◽  
Cell Tropism ◽  
Receptor Binding Site ◽  
Antigenic Properties

Influenza is caused by viruses belonging to the Orthomyxoviridae family. Currently three types of influenza virus are known: A (Influenza A virus, IAV), B (IBV) and C (ICV). Despite the fact that all these viruses are derived from a common ancestor they differ from each other by the number of segments, the size and sequence of RNA segments, antigenicity, pathogenicity and the spectrum of natural reservoirs. In 2011, a new influenza virus was isolated in the USA from pigs manifesting influenza-like symptoms. The virus was the most closely related to ICV. It was able to replicate in vitro in different cell cultures and displayed much broader cell tropism than human ICV. Moreover, in contrast to ICV, it was able to replicate at 370C. Electron microscopic studies demonstrated features characteristic of Orthomyxoviruses. Despite morphological and organizational similarities, the biological properties of the new virus, including biochemical activity, differ from that of other influenza viruses. Enzymatic assays revealed that the new virus had negligible neuraminidase but detectable O-acetyloesterase activity. Further studies evidenced that the new virus varied from ICV in receptor binding, despite its sharing a conserved array of functional domains in the viral RNA genome replication and viral entry machinery. Analysis conducted with the use of the model of crystal structure of the hemagglutinin-esterase fusion protein (HE) of the new virus and its receptor demonstrated that this protein was multifunctional. It catalyzes cellular receptor binding, receptor cleavage, as well as membrane fusion. Moreover, divergent receptor-binding sites than HE of ICV have been discovered in the new virus. These amino acid differences may alter the binding specificity and affinity of the HE protein to the receptor that in turn result in the observed differences in cellular tropism between the two viruses. It also possesses an open channel between the 230-helix and 270-loop in the receptor-binding site, which is a unique feature of this virus. This might explain why the new virus has a broad cell tropism. It is possible that the sequence variation in the fusion domain may influence the replication of this virus at a higher temperature when compared to ICV. Next-generation sequencing demonstrated that the genome of the new virus, similarly to ICV, had seven single-stranded negative-sense RNA segments coding 9 viral proteins. Deep RNA sequencing found a M1 protein expression strategy different from that of ICV. Studies aimed at evaluating of the evolutionary relationship of both viruses revealed that the new virus and ICV shared an approximately 69-72% mean pairwise identity in the PB1 gene, which is reported to be the most conserved influenza virus protein. Additionally, differences were detected at 5’ and 3’ends of noncoding regions, which are also highly conserved. They both may be responsible for the lack of in vitro reassortment between ICV of human origin and the new virus. In the study characterizing antigenic properties of the new virus, no cross-reactivity was observed using HI and AGID tests. This indicates the major differences in conserved proteins M1 and NP between both viruses. Summing up, despite the fact that new virus is the most closely related to human ICV, the number of important antigenic and genetic distinctions among them is the basis for suggesting that the International Committee of Virus Taxonomy classify it as a separate genus - D. There is no doubt that the discovery of a new influenza virus genus will have a great impact on influenza research and ecology.

scholarly journals ANTIGENIC VARIANTS OF INFLUENZA A VIRUS (PR8 STRAIN)

1955 ◽  
Vol 101 (6) ◽  
pp. 627-638 ◽  
Author(s):  
Paul Gerber ◽  
Clayton G. Loosli ◽  
Dorothy Hamre
Keyword(s):  
Influenza A Virus ◽  
Parent Strain ◽  
Influenza A ◽  
Serial Passage ◽  
Virus Multiplication ◽  
Serological Tests ◽  
Virus Growth ◽  
Antibody Absorption ◽  
Antibody Titers ◽  
Different Strains

Antigenically different strains of mouse-adapted PR8 influenza A virus have been produced by 17 serial passages of the virus in the lungs of mice immunized with the homologous agent. Comparative serological tests show that the variant strains share antigenic components with the parent strain but the dominant antigen is different. By means of antibody absorption it was shown that the "new" antigenic component of the variant was already present in minor amounts up to the eighth passage and thereafter gained prominence with continued passage in vaccinated mice. Groups of mice vaccinated with either the PR8-S or T21 virus and having comparable antibody titers showed no growth of virus in the lungs following aid-borne challenge with homologous strains. On the other hand, following heterologous air-borne challenge no deaths occurred, but virus grew in the lungs of both groups of vaccinated mice. Almost unrestricted virus multiplication took place in the lungs of mice vaccinated with the parent strain and challenged with the PR8-T21 virus which resulted in extensive consolidation. Less virus grew in the lungs of the mice vaccinated with the variant strains and challenged with the PR8-S virus. In these animals only microscopic evidence of changes due to virus growth in the lungs was observed. The successful serial passage of PR8 influenza A virus in immunized animals was dependent on the initial selection of mice with uniformly low H.I. antibody titers as determined on tail blood, and the intranasal instillation of sufficient virus to favor the survival of those virus particles least related to the antibodies present. The epidemiological implications of these observations are discussed briefly.

Sign in / Sign up

Export Citation Format

Share Document