High Risk of Influenza Virus Infection Among Swine Workers: Examining a Dynamic Cohort in China

Abstract Background China is thought to be a hotspot for zoonotic influenza virus emergence, yet there have been few prospective studies examining the occupational risks of such infections. Methods We present the first 2 years of data collected from a 5-year, prospective, cohort study of swine-exposed and -unexposed participants at 6 swine farms in China. We conducted serological and virological surveillance to examine evidence for swine influenza A virus infection in humans. Results Of the 658 participants (521 swine-exposed and 137 swine-unexposed), 207 (31.5%) seroconverted against at least 1 swine influenza virus subtype (swine H1N1 or H3N2). Swine-exposed participants’ microneutralization titers, especially those enrolled at confined animal feeding operations (CAFOs), were higher against the swine H1N1 virus than were other participants at 12 and 24 months. Despite elevated titers, among the 187 study subjects for whom we had complete follow-up, participants working at swine CAFOs had significantly greater odds of seroconverting against both the swine H1N1 (odds ratio [OR] 19.16, 95% confidence interval [CI] 3.55–358.65) and swine H3N2 (OR 2.97, 95% CI 1.16–8.01) viruses, compared to unexposed and non-CAFO swine workers with less intense swine exposure. Conclusions While some of the observed increased risk against swine viruses may have been explained by exposure to human influenza strains, study data suggest that even with elevated preexisting antibodies, swine-exposed workers were at high risk of infection with enzootic swine influenza A viruses.

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Elastase-Dependent Live Attenuated Swine Influenza A Viruses Are Immunogenic and Confer Protection against Swine Influenza A Virus Infection in Pigs

Journal of Virology ◽

10.1128/jvi.00926-09 ◽

2009 ◽

Vol 83 (19) ◽

pp. 10198-10210 ◽

Cited By ~ 46

Author(s):

Aleksandar Masic ◽

Jayaum S. Booth ◽

George K. Mutwiri ◽

Lorne A. Babiuk ◽

Yan Zhou

Keyword(s):

Influenza Virus ◽

Virus Infection ◽

Influenza A ◽

Swine Influenza Virus ◽

Influenza Virus Infection ◽

Swine Influenza ◽

Cell Mediated Immunity ◽

Influenza A Viruses ◽

Live Virus ◽

Siv Infection

ABSTRACT Influenza A viruses cause significant morbidity in swine, resulting in a substantial economic burden. Swine influenza virus (SIV) infection also poses important human public health concerns. Vaccination is the primary method for the prevention of influenza virus infection. Previously, we generated two elastase-dependent mutant SIVs derived from A/Sw/Saskatchewan/18789/02(H1N1): A/Sw/Sk-R345V (R345V) and A/Sw/Sk-R345A (R345A). These two viruses are highly attenuated in pigs, making them good candidates for a live-virus vaccine. In this study, the immunogenicity and the ability of these candidates to protect against SIV infection were evaluated in pigs. We report that intratracheally administrated R345V and R345A induced antigen-specific humoral and cell-mediated immunity characterized by increased production of immunoglobulin G (IgG) and IgA antibodies in the serum and in bronchoalveolar lavage fluid, high hemagglutination inhibition titers in serum, an enhanced level of lymphocyte proliferation, and higher numbers of gamma interferon-secreting cells at the site of infection. Based on the immunogenicity results, the R345V virus was further tested in a protection trial in which pigs were vaccinated twice with R345V and then challenged with homologous A/Sw/Saskatchewan/18789/02, H1N1 antigenic variant A/Sw/Indiana/1726/88 or heterologous subtypic H3N2 A/Sw/Texas/4199-2/9/98. Our data showed that two vaccinations with R345V provided pigs with complete protection from homologous H1N1 SIV infection and partial protection from heterologous subtypic H3N2 SIV infection. This protection was characterized by significantly reduced macroscopic and microscopic lung lesions, lower virus titers from the respiratory tract, and lower levels of proinflammatory cytokines. Thus, elastase-dependent SIV mutants can be used as live-virus vaccines against swine influenza in pigs.

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Spatiotemporal Distribution and Evolution of the A/H1N1 2009 Pandemic Influenza Virus in Pigs in France from 2009 to 2017: Identification of a Potential Swine-Specific Lineage

Journal of Virology ◽

10.1128/jvi.00988-18 ◽

2018 ◽

Vol 92 (24) ◽

Cited By ~ 12

Author(s):

Amélie Chastagner ◽

Séverine Hervé ◽

Emilie Bonin ◽

Stéphane Quéguiner ◽

Edouard Hirchaud ◽

...

Keyword(s):

Influenza Virus ◽

Influenza A ◽

Phylogenetic Analyses ◽

Swine Influenza ◽

H1n1 Influenza ◽

Antigenic Drift ◽

Influenza A Viruses ◽

Evolutionary Patterns ◽

Increased Risk ◽

Na Sequences

ABSTRACT The H1N1 influenza virus responsible for the most recent pandemic in 2009 (H1N1pdm) has spread to swine populations worldwide while it replaced the previous seasonal H1N1 virus in humans. In France, surveillance of swine influenza A viruses in pig herds with respiratory outbreaks led to the detection of 44 H1N1pdm strains between 2009 and 2017, regardless of the season, and findings were not correlated with pig density. From these isolates, 17 whole-genome sequences were obtained, as were 6 additional hemagglutinin (HA)/neuraminidase (NA) sequences, in order to perform spatial and temporal analyses of genetic diversity and to compare evolutionary patterns of H1N1pdm in pigs to patterns for human strains. Following mutation accumulation and fixation over time, phylogenetic analyses revealed for the first time the divergence of a swine-specific genogroup within the H1N1pdm lineage. The divergence is thought to have occurred around 2011, although this was demonstrated only through strains isolated in 2015 to 2016 in the southern half of France. To date, these H1N1pdm swine strains have not been related to any increased virulence in swine herds and have not exhibited any antigenic drift compared to seasonal human strains. However, further monitoring is encouraged, as diverging evolutionary patterns in these two species, i.e., swine and humans, may lead to the emergence of viruses with a potentially higher risk to both animal and human health.IMPORTANCE Pigs are a “mixing vessel” for influenza A viruses (IAVs) because of their ability to be infected by avian and human IAVs and their propensity to facilitate viral genomic reassortment events. Also, as IAVs may evolve differently in swine and humans, pigs can become a reservoir for old human strains against which the human population has become immunologically naive. Thus, viruses from the novel swine-specific H1N1pdm genogroup may continue to diverge from seasonal H1N1pdm strains and/or from other H1N1pdm viruses infecting pigs and lead to the emergence of viruses that would not be covered by human vaccines and/or swine vaccines based on antigens closely related to the original H1N1pdm virus. This discovery confirms the importance of encouraging swine IAV monitoring because H1N1pdm swine viruses could carry an increased risk to both human and swine health in the future as a whole H1N1pdm virus or gene provider in subsequent reassortant viruses.

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Mitochondrial antiviral signaling adaptor mediated apoptosis in H3N2 swine influenza virus infection is inhibited by viral protein NS1 in vitro

Veterinary Immunology and Immunopathology ◽

10.1016/j.vetimm.2015.03.003 ◽

2015 ◽

Vol 165 (1-2) ◽

pp. 34-44 ◽

Cited By ~ 3

Author(s):

Jinqiu Zhang ◽

Jinfeng Miao ◽

Jibo Hou ◽

Chengping Lu

Keyword(s):

Influenza Virus ◽

Virus Infection ◽

Viral Protein ◽

Swine Influenza Virus ◽

Influenza Virus Infection ◽

Swine Influenza ◽

Antiviral Signaling ◽

Mitochondrial Antiviral Signaling

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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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Role of IFN-α during the acute stage of a swine influenza virus infection

Research in Veterinary Science ◽

10.1016/j.rvsc.2009.07.001 ◽

2010 ◽

Vol 88 (1) ◽

pp. 172-178 ◽

Cited By ~ 16

Author(s):

Filip Barbé ◽

Xavier Saelens ◽

Debby Braeckmans ◽

François Lefèvre ◽

Kristien Van Reeth

Keyword(s):

Influenza Virus ◽

Virus Infection ◽

Swine Influenza Virus ◽

Influenza Virus Infection ◽

Swine Influenza ◽

Acute Stage

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Evaluation of Three Commercially Available Influenza A Type-Specific Blocking Enzyme-Linked Immunosorbent Assays for Seroepidemiological Studies of Influenza A Virus Infection in Pigs

Clinical and Vaccine Immunology ◽

10.1128/cvi.05358-11 ◽

2012 ◽

Vol 19 (3) ◽

pp. 334-337 ◽

Cited By ~ 15

Author(s):

Maying Tse ◽

Mia Kim ◽

Chung-Hei Chan ◽

Po-Lai Ho ◽

Siu-Kit Ma ◽

...

Keyword(s):

Influenza Virus ◽

Virus Infection ◽

Influenza A Virus ◽

Sensitivity And Specificity ◽

Influenza A ◽

Influenza Virus Infection ◽

Swine Influenza ◽

Immunosorbent Assays ◽

Cutoff Levels ◽

Antibody Competition

ABSTRACTThe reverse zoonotic transmission of the pandemic H1N1 2009 influenza virus to swine necessitates enhanced surveillance of swine for influenza virus infection. Using a well-characterized panel of naturally infected swine sera, we evaluated and optimized the performances of three commercially available competitive enzyme-linked immunosorbent assays (ELISAs), namely, the IDEXX Influenza A Ab test, IDEXX AI MultiS-Screen Ab test, and IDVet ID Screen influenza A antibody competition ELISA, for detecting influenza A virus-reactive antibodies in swine. Receiver operating characteristic (ROC) analysis suggests that adjustment of the manufacturer-recommended cutoff values optimizes the sensitivity and specificity of these assays, making them applicable for seroepidemiology studies of swine influenza. Using such optimized cutoff levels, the sensitivity and specificity of the IDEXX Influenza A Ab test were 86% and 89%, respectively; those for the IDEXX AI MultiS-Screen Ab test were 91% and 87%, respectively; and those for the IDVet ID Screen influenza A test were 95% and 79%, respectively.

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