Detection of Antigenic Variants of Subtype H3 Swine Influenza A Viruses from Clinical Samples

ABSTRACT A large population of genetically and antigenically diverse influenza A viruses (IAVs) are circulating among the swine population, playing an important role in influenza ecology. Swine IAVs not only cause outbreaks among swine but also can be transmitted to humans, causing sporadic infections and even pandemic outbreaks. Antigenic characterizations of swine IAVs are key to understanding the natural history of these viruses in swine and to selecting strains for effective vaccines. However, influenza outbreaks generally spread rapidly among swine, and the conventional methods for antigenic characterization require virus propagation, a time-consuming process that can significantly reduce the effectiveness of vaccination programs. We developed and validated a rapid, sensitive, and robust method, the polyclonal serum-based proximity ligation assay (polyPLA), to identify antigenic variants of subtype H3N2 swine IAVs. This method utilizes oligonucleotide-conjugated polyclonal antibodies and quantifies antibody-antigen binding affinities by quantitative reverse transcription-PCR (RT-PCR). Results showed the assay can rapidly detect H3N2 IAVs directly from nasal wash or nasal swab samples collected from laboratory-challenged animals or during influenza surveillance at county fairs. In addition, polyPLA can accurately separate the viruses at two contemporary swine IAV antigenic clusters (H3N2 swine IAV-α and H3N2 swine IAV-ß) with a sensitivity of 84.9% and a specificity of 100.0%. The polyPLA can be routinely used in surveillance programs to detect antigenic variants of influenza viruses and to select vaccine strains for use in controlling and preventing disease in swine.

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Swine influenza vaccines: current status and future perspectives

Animal Health Research Reviews ◽

10.1017/s146625231000006x ◽

2010 ◽

Vol 11 (1) ◽

pp. 81-96 ◽

Cited By ~ 41

Author(s):

Wenjun Ma ◽

Jürgen A. Richt

Keyword(s):

Influenza A ◽

Swine Influenza ◽

Influenza Viruses ◽

Current Status ◽

Economic Losses ◽

Influenza A Viruses ◽

Swine Industry ◽

Effective Strategies ◽

Swine Disease ◽

And Control

AbstractSwine influenza is an important contagious disease in pigs caused by influenza A viruses. Although only three subtypes of influenza A viruses, H1N1, H1N2 and H3N2, predominantly infect pigs worldwide, it is still a big challenge for vaccine manufacturers to produce efficacious vaccines for the prevention and control of swine influenza. Swine influenza viruses not only cause significant economic losses for the swine industry, but are also important zoonotic pathogens. Vaccination is still one of the most important and effective strategies to prevent and control influenza for both the animal and human population. In this review, we will discuss the current status of swine influenza worldwide as well as current and future options to control this economically important swine disease.

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Improving pandemic influenza risk assessment

eLife ◽

10.7554/elife.03883 ◽

2014 ◽

Vol 3 ◽

Cited By ~ 43

Author(s):

Colin A Russell ◽

Peter M Kasson ◽

Ruben O Donis ◽

Steven Riley ◽

John Dunbar ◽

...

Keyword(s):

Risk Assessment ◽

Pandemic Influenza ◽

Influenza A ◽

Sequence Data ◽

Virus Genome ◽

Influenza Viruses ◽

Influenza Surveillance ◽

Human Influenza ◽

Influenza A Viruses ◽

Virus Genotype

Assessing the pandemic risk posed by specific non-human influenza A viruses is an important goal in public health research. As influenza virus genome sequencing becomes cheaper, faster, and more readily available, the ability to predict pandemic potential from sequence data could transform pandemic influenza risk assessment capabilities. However, the complexities of the relationships between virus genotype and phenotype make such predictions extremely difficult. The integration of experimental work, computational tool development, and analysis of evolutionary pathways, together with refinements to influenza surveillance, has the potential to transform our ability to assess the risks posed to humans by non-human influenza viruses and lead to improved pandemic preparedness and response.

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Divergent Human-Origin Influenza Viruses Detected in Australian Swine Populations

Journal of Virology ◽

10.1128/jvi.00316-18 ◽

2018 ◽

Vol 92 (16) ◽

Cited By ~ 6

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.

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Respiratory Illness in a Piggery Associated with the First Identified Outbreak of Swine Influenza in Australia: Assessing the Risk to Human Health and Zoonotic Potential

Tropical Medicine and Infectious Disease ◽

10.3390/tropicalmed4020096 ◽

2019 ◽

Vol 4 (2) ◽

pp. 96 ◽

Cited By ~ 2

Author(s):

David W. Smith ◽

Ian G. Barr ◽

Richmond Loh ◽

Avram Levy ◽

Simone Tempone ◽

...

Keyword(s):

Influenza A ◽

Haemagglutination Inhibition ◽

Swine Influenza ◽

Respiratory Illness ◽

Influenza Viruses ◽

Influenza A Viruses ◽

Strict Adherence ◽

Zoonotic Infections ◽

Zoonotic Risk ◽

Biosecurity Practices

Australia was previously believed to be free of enzootic swine influenza viruses due strict quarantine practices and use of biosecure breeding facilities. The first proven Australian outbreak of swine influenza occurred in Western Australian in 2012, revealing an unrecognized zoonotic risk, and a potential future pandemic threat. A public health investigation was undertaken to determine whether zoonotic infections had occurred and to reduce the risk of further transmission between humans and swine. A program of monitoring, testing, treatment, and vaccination was commenced, and a serosurvey of workers was also undertaken. No acute infections with the swine influenza viruses were detected. Serosurvey results were difficult to interpret due to previous influenza infections and past and current vaccinations. However, several workers had elevated haemagglutination inhibition (HI) antibody levels to the swine influenza viruses that could not be attributed to vaccination or infection with contemporaneous seasonal influenza A viruses. However, we lacked a suitable control population, so this was inconclusive. The experience was valuable in developing better protocols for managing outbreaks at the human–animal interface. Strict adherence to biosecurity practices, and ongoing monitoring of swine and their human contacts is important to mitigate pandemic risk. Strain specific serological assays would greatly assist in identifying zoonotic transmission.

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Influenza viruses: transmission between species

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1980.0021 ◽

1980 ◽

Vol 288 (1029) ◽

pp. 439-447 ◽

Cited By ~ 9

Keyword(s):

Influenza A ◽

Direct Evidence ◽

Swine Influenza ◽

Indirect Evidence ◽

Preliminary Evidence ◽

Influenza Viruses ◽

Surface Proteins ◽

Aquatic Birds ◽

Influenza A Viruses ◽

Wide Range

The only direct evidence for transmission of influenza viruses between species comes from studies on swine influenza viruses. Antigenically and genetically identical Hsw1N1 influenza viruses were isolated from pigs and man on the same farm in Wisconsin, U.S.A. The isolation of H3N2 influenza viruses from a wide range of lower animals and birds suggests that influenza viruses of man can spread to the lower orders. Under some conditions the H3N2 viruses can persist for a number of years in some species. The isolation, from aquatic birds, of a large number of influenza A viruses that possess surface proteins antigenically similar to the viruses isolated from man, pigs and horses provides indirect evidence for inter-species transmission. There is now a considerable body of evidence which suggests that influenza viruses of lower animals and birds may play a role in the origin of some of the pandemic strains of influenza A viruses. There is no direct evidence that the influenza viruses in aquatic birds are transmitted to man, but they may serve as a genetic pool from which some genes may be introduced into humans by recombination. Preliminary evidence suggests that the molecular basis of host range and virulence may be related to the RNA segments coding for one of the polymerase proteins (P3) and for the nucleoprotein (NP).

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The evolutionary dynamics of influenza A virus adaptation to mammalian hosts

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2012.0382 ◽

2013 ◽

Vol 368 (1614) ◽

pp. 20120382 ◽

Cited By ~ 27

Author(s):

S. Bhatt ◽

T. T. Lam ◽

S. J. Lycett ◽

A. J. Leigh Brown ◽

T. A. Bowden ◽

...

Keyword(s):

Avian Influenza ◽

Adaptive Evolution ◽

Influenza A ◽

Evolutionary Dynamics ◽

Adaptive Dynamics ◽

Swine Influenza ◽

Influenza Viruses ◽

Viral Fitness ◽

Influenza A Viruses ◽

Entire Genome

Few questions on infectious disease are more important than understanding how and why avian influenza A viruses successfully emerge in mammalian populations, yet little is known about the rate and nature of the virus’ genetic adaptation in new hosts. Here, we measure, for the first time, the genomic rate of adaptive evolution of swine influenza viruses (SwIV) that originated in birds. By using a curated dataset of more than 24 000 human and swine influenza gene sequences, including 41 newly characterized genomes, we reconstructed the adaptive dynamics of three major SwIV lineages (Eurasian, EA; classical swine, CS; triple reassortant, TR). We found that, following the transfer of the EA lineage from birds to swine in the late 1970s, EA virus genes have undergone substantially faster adaptive evolution than those of the CS lineage, which had circulated among swine for decades. Further, the adaptation rates of the EA lineage antigenic haemagglutinin and neuraminidase genes were unexpectedly high and similar to those observed in human influenza A. We show that the successful establishment of avian influenza viruses in swine is associated with raised adaptive evolution across the entire genome for many years after zoonosis, reflecting the contribution of multiple mutations to the coordinated optimization of viral fitness in a new environment. This dynamics is replicated independently in the polymerase genes of the TR lineage, which established in swine following separate transmission from non-swine hosts.

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Resurrected ancestral influenza A viruses recapitulate the avian-to-mammalian adaptation of European avian-like swine influenza virus

10.21203/rs.3.rs-436907/v1 ◽

2021 ◽

Author(s):

Wen Su ◽

Rhodri Harfoot ◽

Yvonne Su ◽

Jennifer DeBeauchamp ◽

Udayan Joseph ◽

...

Keyword(s):

Influenza Virus ◽

Avian Influenza ◽

Influenza A ◽

Swine Influenza Virus ◽

Swine Influenza ◽

Polymerase Activity ◽

Influenza Viruses ◽

Mammalian Host ◽

Influenza A Viruses ◽

Sequence Reconstruction

Abstract The emergence of a pandemic influenza virus may be better anticipated if we better understand the evolutionary steps taken by avian influenza viruses as they adapt to mammals. We used ancestral sequence reconstruction to resurrect viruses representing initial adaptive stages of the European avian-like H1N1 virus as it transitioned from avian to swine hosts. We demonstrate that efficient transmissibility in pigs was gained through stepwise adaptation after 1983. These time-dependent adaptations resulted in changes in hemagglutinin receptor binding specificity and increased viral polymerase activity. An NP-R351K mutation under strong positive selection increased the transmissibility of a reconstructed virus. The stepwise-adaptation of a wholly avian influenza virus to a mammalian host suggests a window where targeted intervention may have highest impact. Successful intervention will, however, require strategic coordination of surveillance and risk assessment activities to identify these adapting viruses and guide pandemic preparedness resources.

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Efficient whole genome sequencing of influenza A viruses

10.1101/749234 ◽

2019 ◽

Author(s):

Marina Escalera-Zamudio ◽

Ana Georgina Cobián-Güemes ◽

Blanca Taboada ◽

Irma López-Martínez ◽

Joel Armando Vázquez-Pérez ◽

...

Keyword(s):

Whole Genome Sequencing ◽

Influenza A Virus ◽

Genome Sequencing ◽

Influenza A ◽

Genetic Material ◽

Influenza Viruses ◽

Epidemiological Surveillance ◽

Clinical Samples ◽

Whole Genome ◽

Influenza A Viruses

ABSTRACTThe constant threat of emergence for novel pathogenic influenza A viruses with pandemic potential, makes full-genome characterization of circulating influenza viral strains a high priority, allowing detection of novel and re-assorting variants. Sequencing the full-length genome of influenza A virus traditionally required multiple amplification rounds, followed by the subsequent sequencing of individual PCR products. The introduction of high-throughput sequencing technologies has made whole genome sequencing easier and faster. We present a simple protocol to obtain whole genome sequences of hypothetically any influenza A virus, even with low quantities of starting genetic material. The complete genomes of influenza A viruses of different subtypes and from distinct sources (clinical samples of pdmH1N1, tissue culture-adapted H3N2 viruses, or avian influenza viruses from cloacal swabs) were amplified with a single multisegment reverse transcription-PCR reaction and sequenced using Illumina sequencing platform. Samples with low quantity of genetic material after initial PCR amplification were re-amplified by an additional PCR using random primers. Whole genome sequencing was successful for 66% of the samples, whilst the most relevant genome segments for epidemiological surveillance (corresponding to the hemagglutinin and neuraminidase) were sequenced with at least 93% coverage (and a minimum 10x) for 98% of the samples. Low coverage for some samples is likely due to an initial low viral RNA concentration in the original sample. The proposed methodology is especially suitable for sequencing a large number of samples, when genetic data is urgently required for strains characterization, and may also be useful for variant analysis.

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Independence of Evolutionary and Mutational Rates after Transmission of Avian Influenza Viruses to Swine

Journal of Virology ◽

10.1128/jvi.73.3.1878-1884.1999 ◽

1999 ◽

Vol 73 (3) ◽

pp. 1878-1884 ◽

Cited By ~ 55

Author(s):

J. Stech ◽

X. Xiong ◽

C. Scholtissek ◽

R. G. Webster

Keyword(s):

New York ◽

Avian Influenza ◽

Influenza A ◽

Swine Influenza ◽

Influenza Viruses ◽

Mutation Rates ◽

Influenza A Viruses ◽

Species Barrier ◽

H1n1 Strain ◽

Serologic Evidence

ABSTRACT In 1979, an H1N1 avian influenza virus crossed the species barrier, establishing a new lineage in European swine. Because there is no direct or serologic evidence of previous H1N1 strains in these pigs, these isolates provide a model for studying early evolution of influenza viruses. The evolutionary rates of both the coding and noncoding changes of the H1N1 swine strains are higher than those of human and classic swine influenza A viruses. In addition, early H1N1 swine isolates show a marked plaque heterogeneity that consistently appears after a few passages. The presence of a mutator mutation was postulated (C. Scholtissek, S. Ludwig, and W. M. Fitch, Arch. Virol. 131:237–250, 1993) to account for these observations and the successful establishment of an avian H1N1 strain in swine. To address this question, we calculated the mutation rates of A/Mallard/New York/6750/78 (H2N2) and A/Swine/Germany/2/81 (H1N1) by using the frequency of amantadine-resistant mutants. To account for the inherent variability of estimated mutation rates, we used a probabilistic model for the statistical analysis. The resulting estimated mutation rates of the two strains were not significantly different. Therefore, an increased mutation rate due to the presence of a mutator mutation is unlikely to have led to the successful introduction of avian H1N1 viruses in European swine.

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The global antigenic diversity of swine influenza A viruses

eLife ◽

10.7554/elife.12217 ◽

2016 ◽

Vol 5 ◽

Cited By ~ 80

Author(s):

Nicola S Lewis ◽

Colin A Russell ◽

Pinky Langat ◽

Tavis K Anderson ◽

Kathryn Berger ◽

...

Keyword(s):

Influenza A ◽

Disease Burden ◽

Swine Influenza Virus ◽

Swine Influenza ◽

Influenza Viruses ◽

Influenza A Viruses ◽

Antigenic Diversity ◽

Continental Scale ◽

Pandemic Threat ◽

Different Parts

Swine influenza presents a substantial disease burden for pig populations worldwide and poses a potential pandemic threat to humans. There is considerable diversity in both H1 and H3 influenza viruses circulating in swine due to the frequent introductions of viruses from humans and birds coupled with geographic segregation of global swine populations. Much of this diversity is characterized genetically but the antigenic diversity of these viruses is poorly understood. Critically, the antigenic diversity shapes the risk profile of swine influenza viruses in terms of their epizootic and pandemic potential. Here, using the most comprehensive set of swine influenza virus antigenic data compiled to date, we quantify the antigenic diversity of swine influenza viruses on a multi-continental scale. The substantial antigenic diversity of recently circulating viruses in different parts of the world adds complexity to the risk profiles for the movement of swine and the potential for swine-derived infections in humans.

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