Expanded Cocirculation of Stable Subtypes, Emerging Lineages, and New Sporadic Reassortants of Porcine Influenza Viruses in Swine Populations in Northwest Germany

Harder, Timm C.; Beilage, Elisabeth große; Lange, Elke; Meiners, César; Döhring, S.; Pesch, S.; Noe, T.; Grund, Christian; Beer, Martin; Starick, Elke

doi:10.1128/jvi.00381-13

Cited by 45 publications

(75 citation statements)

References 59 publications

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“…However, given our findings, and observations of new reassortant strains elsewhere in Europe47, 48, there should be no assumption that reassortment with possible zoonotic risk could not also occur in industrialised settings.…”

Section: Discussionmentioning

confidence: 58%

Increased risk of A(H1N1)pdm09 influenza infection in UK pig industry workers compared to a general population cohort

Fragaszy

Ishola

Brown

et al. 2016

Influenza Resp Viruses

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BackgroundPigs are mixing vessels for influenza viral reassortment, but the extent of influenza transmission between swine and humans is not well understood.ObjectivesTo assess whether occupational exposure to pigs is a risk factor for human infection with human and swine‐adapted influenza viruses.Methods UK pig industry workers were frequency‐matched on age, region, sampling month, and gender with a community‐based comparison group from the Flu Watch study. HI assays quantified antibodies for swine and human A(H1) and A(H3) influenza viruses (titres ≥ 40 considered seropositive and indicative of infection). Virus‐specific associations between seropositivity and occupational pig exposure were examined using multivariable regression models adjusted for vaccination. Pigs on the same farms were also tested for seropositivity.ResultsForty‐two percent of pigs were seropositive to A(H1N1)pdm09. Pig industry workers showed evidence of increased odds of A(H1N1)pdm09 seropositivity compared to the comparison group, albeit with wide confidence intervals (CIs), adjusted odds ratio after accounting for possible cross‐reactivity with other swine A(H1) viruses (aOR) 25·3, 95% CI (1·4–536·3), P = 0·028.ConclusionThe results indicate that A(H1N1)pdm09 virus was common in UK pigs during the pandemic and subsequent period of human A(H1N1)pdm09 circulation, and occupational exposure to pigs was a risk factor for human infection. Influenza immunisation of pig industry workers may reduce transmission and the potential for virus reassortment.

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Section: Discussionmentioning

confidence: 58%

Increased risk of A(H1N1)pdm09 influenza infection in UK pig industry workers compared to a general population cohort

Fragaszy

Ishola

Brown

et al. 2016

Influenza Resp Viruses

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“…The pH1N1 virus has established itself as the dominant circulating seasonal H1N1 virus, and based on extensive surveillance studies in swine, reverse zoonosis has been identified worldwide (10)(11)(12)(13)(14)(15)(16)(17). pH1N1 harbors the ability to be transmitted very efficiently from human to human based on transmission analyses from the 2009 outbreak and detailed ferret transmission studies (73).…”

Section: Discussionmentioning

confidence: 99%

“…Since the emergence of 2009 pandemic pH1N1 virus, reverse zoonosis to swine has been globally observed (7)(8)(9)(10)(11)(12)(13)(14). North American classical swine viruses, European or Eurasian avian virus-like swine viruses, and triple reassortment of internal gene (TRIG) swine viruses cocirculate in swine populations today (15).…”

Section: Importancementioning

confidence: 99%

“…In the past century, four IAV pandemics have occurred, i.e., 1918, 1956, 1968, and 2009 (4), and the last three events resulted from reassortment events occurring between IAVs of different origins (5). The 2009 pandemic resulted from triple reassortment of human, avian, and North American and Eurasian swine-origin viruses (6), and through competitive exclusion (4), this pandemic strain has become the dominant circulating virus, replacing the previous seasonal H1N1 strains of IAV.Since the emergence of 2009 pandemic pH1N1 virus, reverse zoonosis to swine has been globally observed (7)(8)(9)(10)(11)(12)(13)(14). North American classical swine viruses, European or Eurasian avian virus-like swine viruses, and triple reassortment of internal gene (TRIG) swine viruses cocirculate in swine populations today (15).…”

mentioning

confidence: 99%

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Swine Influenza Virus PA and Neuraminidase Gene Reassortment into Human H1N1 Influenza Virus Is Associated with an Altered Pathogenic Phenotype Linked to Increased MIP-2 Expression

Dlugolenski

Jones

Howerth

et al. 2015

J Virol

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Swine are susceptible to infection by both avian and human influenza viruses, and this feature is thought to contribute to novel reassortant influenza viruses. In this study, the influenza virus reassortment rate in swine and human cells was determined. Coinfection of swine cells with 2009 pandemic H1N1 virus (huH1N1) and an endemic swine H1N2 (A/swine/Illinois/02860/09) virus (swH1N2) resulted in a 23% reassortment rate that was independent of ␣2,3-or ␣2,6-sialic acid distribution on the cells. The reassortants had altered pathogenic phenotypes linked to introduction of the swine virus PA and neuraminidase (NA) into huH1N1. In mice, the huH1N1 PA and NA mediated increased MIP-2 expression early postinfection, resulting in substantial pulmonary neutrophilia with enhanced lung pathology and disease. The findings support the notion that swine are a mixing vessel for influenza virus reassortants independent of sialic acid distribution. These results show the potential for continued reassortment of the 2009 pandemic H1N1 virus with endemic swine viruses and for reassortants to have increased pathogenicity linked to the swine virus NA and PA genes which are associated with increased pulmonary neutrophil trafficking that is related to MIP-2 expression. IMPORTANCEInfluenza A viruses can change rapidly via reassortment to create a novel virus, and reassortment can result in possible pandemics. Reassortments among subtypes from avian and human viruses led to the 1957 (H2N2 subtype) and 1968 (H3N2 subtype) human influenza pandemics. Recent analyses of circulating isolates have shown that multiple genes can be recombined from human, avian, and swine influenza viruses, leading to triple reassortants. Understanding the factors that can affect influenza A virus reassortment is needed for the establishment of disease intervention strategies that may reduce or preclude pandemics. The findings from this study show that swine cells provide a mixing vessel for influenza virus reassortment independent of differential sialic acid distribution. The findings also establish that circulating neuraminidase (NA) and PA genes could alter the pathogenic phenotype of the pandemic H1N1 virus, resulting in enhanced disease. The identification of such factors provides a framework for pandemic modeling and surveillance. E ach year, influenza A viruses (IAVs) cause epidemics with high morbidity and some mortality in humans (1). In avian species, IAV infection generally is associated with mild disease, and it is only when the virus crosses species barriers that pathogenic traits are attributed to infection (2). IAV is frequently associated with spillover events, as numerous species are susceptible to IAV. Often, reassortment of IAV leads to a subtype or variant that has not previously infected humans, and as the virus adapts and is transmitted more easily, a pandemic event may loom. IAV is the cause of Ͼ30,000 deaths in the United States and Ͼ500,000 deaths worldwide annually (3). In the past century, four IAV pandemics have occurred, i.e....

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“…Moreover, the generation of novel escape mutants could gradually lead to the replacement of circulating virus strains (19,20), further complicating the antigenic and genetic evolution of swine IAVs. The occurrence of such antigenic drift events in swine is well documented (7,21,22). To develop an effective and robust swine IAV vaccination program, a rapid and robust method for antigenic characterization in swine is needed.…”

mentioning

confidence: 99%

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

Martin

Bowman

et al. 2017

J Clin Microbiol

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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 timeconsuming 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 laboratorychallenged 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-␣ 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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Expanded Cocirculation of Stable Subtypes, Emerging Lineages, and New Sporadic Reassortants of Porcine Influenza Viruses in Swine Populations in Northwest Germany

Cited by 45 publications

References 59 publications

Increased risk of A(H1N1)pdm09 influenza infection in UK pig industry workers compared to a general population cohort

Increased risk of A(H1N1)pdm09 influenza infection in UK pig industry workers compared to a general population cohort

Swine Influenza Virus PA and Neuraminidase Gene Reassortment into Human H1N1 Influenza Virus Is Associated with an Altered Pathogenic Phenotype Linked to Increased MIP-2 Expression

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

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