Gaps in Serologic Immunity against Contemporary Swine-Origin Influenza A Viruses among Healthy Individuals in the United States

Lorbach, Joshua N.; Fitzgerald, Theresa; Nolan, Carolyn; Nolting, Jacqueline M.; Treanor, John J.; Topham, David J.; Bowman, Andrew S.

doi:10.3390/v13010127

Cited by 6 publications

(5 citation statements)

References 40 publications

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“…The higher incidence in children could be because of a lack of antigenic immunity to the A(H3N2)v viruses in this age group. Evidence suggests that nearly all children under the age of 5 years and >80% of children under the age of 14 years in a general population lack neutralizing antibodies to swine-origin A(H3N2) viruses (Skowronski et al, 2012) (Lorbach, Fitzgerald, et al, 2021). Further work is required to characterize the protection status specifically for children with frequent exposure to swine at this type of human-animal interface to fully resolve drivers of zoonotic transmission.…”

Section: Discussionmentioning

confidence: 99%

“…IAVs with pandemic potential must be unique enough antigenically to evade population level immunity and must be sufficiently adapted to easily spread from person-toperson (Zimmerman et al, 2012). Genotypic diversity and frequent reassortment of IAVs in swine populations can make them a source of emergent IAVs to which the human population lacks immunity and may lead to the emergence of viruses with unpredictable transmissibility and pathogenesis (Lorbach, Fitzgerald, et al, 2021). Rambo-Martin et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

“…Evidence suggests that nearly all children under the age of 5 years and >80% of children under the age of 14 years in a general population lack neutralizing antibodies to swine‐origin A(H3N2) viruses (Skowronski et al., 2012), potentially owing to a lack of prior immunity from vaccination or infection. Additionally, healthy juveniles (born between 2004 and 2013) in the United States have low or no serum antibody titers cross‐reactive with several swine‐origin IAVs indicating a potential gap in protection in this age group (Lorbach, Fitzgerald, et al., 2021). Further work is required to characterize the protection status specifically for children with frequent exposure to swine at this type of human‐animal interface to fully resolve drivers of zoonotic transmission.…”

Section: Discussionmentioning

confidence: 99%

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Evolution of influenza A viruses in exhibition swine and transmission to humans, 2013–2015

Szablewski,

McBride,

Trock

et al. 2023

Zoonoses and Public Health

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AimsSwine are a mixing vessel for the emergence of novel reassortant influenza A viruses (IAV). Interspecies transmission of swine‐origin IAV poses a public health and pandemic risk. In the United States, the majority of zoonotic IAV transmission events have occurred in association with swine exposure at agricultural fairs. Accordingly, this human‐animal interface necessitates mitigation strategies informed by understanding of interspecies transmission mechanisms in exhibition swine. Likewise, the diversity of IAV in swine can be a source for novel reassortant or mutated viruses that pose a risk to both swine and human health.Methods and ResultsIn an effort to better understand those risks, here we investigated the epidemiology of IAV in exhibition swine and subsequent transmission to humans by performing phylogenetic analyses using full genome sequences from 272 IAV isolates collected from exhibition swine and 23 A(H3N2)v viruses from human hosts during 2013–2015. Sixty‐seven fairs (24.2%) had at least one pig test positive for IAV with an overall estimated prevalence of 8.9% (95% CI: 8.3–9.6, Clopper‐Pearson). Of the 19 genotypes found in swine, 5 were also identified in humans. There was a positive correlation between the number of human cases of a genotype and its prevalence in exhibition swine. Additionally, we demonstrated that A(H3N2)v viruses clustered tightly with exhibition swine viruses that were prevalent in the same year.ConclusionsThese data indicate that multiple genotypes of swine‐lineage IAV have infected humans, and highly prevalent IAV genotypes in exhibition swine during a given year are also the strains detected most frequently in human cases of variant IAV. Continued surveillance and rapid characterization of IAVs in exhibition swine can facilitate timely phenotypic evaluation and matching of candidate vaccine strains to those viruses present at the human‐animal interface which are most likely to spillover into humans.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Evolution of influenza A viruses in exhibition swine and transmission to humans, 2013–2015

Szablewski,

McBride,

Trock

et al. 2023

Zoonoses and Public Health

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“…This has resulted in an increasingly dominant endemic virus within commercial herds as well as several human cases of H1N2 variant (H1N2v) viruses [ 6 ]. The ability of these swine viruses to spill back into human populations suggests there is limited immunity from cross-protective antibodies elicited by human seasonal influenza [ 7 ]. As such, increased surveillance efforts have been focused on these viruses.…”

Section: Introductionmentioning

confidence: 99%

Pandemic Risk Assessment for Swine Influenza A Virus in Comparative In Vitro and In Vivo Models

Padykula,

Damodaran,

Young

et al. 2024

Viruses

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Swine influenza A viruses pose a public health concern as novel and circulating strains occasionally spill over into human hosts, with the potential to cause disease. Crucial to preempting these events is the use of a threat assessment framework for human populations. However, established guidelines do not specify which animal models or in vitro substrates should be used. We completed an assessment of a contemporary swine influenza isolate, A/swine/GA/A27480/2019 (H1N2), using animal models and human cell substrates. Infection studies in vivo revealed high replicative ability and a pathogenic phenotype in the swine host, with replication corresponding to a complementary study performed in swine primary respiratory epithelial cells. However, replication was limited in human primary cell substrates. This contrasted with our findings in the Calu-3 cell line, which demonstrated a replication profile on par with the 2009 pandemic H1N1 virus. These data suggest that the selection of models is important for meaningful risk assessment.

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“…Thus, prevalence of such antibodies against animal H3 IAVs in persons of different age groups can be used to estimate the public health risk (18). Recent seroprevalence studies are available for H3 IAVs from swine in North America, but studies in Europe were conducted with samples and IAVs collected before 2011 (7)(8)(9)(10)19). Studies for H3 IAVs from birds and equids are generally lacking, except for a few small-scale studies with historic IAV strains (20)(21)(22)(23)(24).…”

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confidence: 99%

Human Immunity and Susceptibility to Influenza A(H3) Viruses of Avian, Equine, and Swine Origin

Vandoorn¹,

Stadejek²,

Leroux-Roels³

et al. 2023

Emerg. Infect. Dis.

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I nfluenza A viruses (IAVs) of the H3 subtype are endemic to humans, swine, and wild birds; they also cause outbreaks in horses and are often detected in domestic birds. An H3 IAV that crosses the species barrier from animals to humans can result in a pandemic if the virus carries a hemagglutinin (HA) against which humans lack protective antibodies and the virus readily replicates in and spreads among humans. For example, in 1968, transmission of an IAV with an avian-origin H3 HA to humans caused the influenza A(H3N2) pandemic (1).The natural IAV reservoir is considered to be wild waterfowl, but transmission to domestic poultry is frequent. Avian H3 IAVs are classified as Eurasian and North American lineages, although the HA of these viruses is antigenically closely related (2,3). In contrast, after being introduced to humans in 1968, the HA of human H3 IAVs quickly drifted away from that of the avian precursor IAV. Consequently, contemporary human H3 IAVs are antigenically divergent from those in birds (2). Similarly, avian H3 IAVs were introduced into horses in the 1960s, after which their HA antigenically drifted. That evolution was, however, different and slower than for human H3 IAVs (4). Equine H3 IAVs of Florida clade 1 (FC1) are currently predominant (5). All swine H3 IAVs derived their HA from human IAVs.H3 IAVs from swine in Europe originated from a human IAV that circulated in the late 1970s. Of the 2 major lineages cocirculating in North America, cluster IV-A was derived from human IAVs from the late 1990s and novel human-like swine H3 IAVs from human IAVs from the early 2010s (6). H3 IAVs undergo slower antigenic drift in swine than in humans. Consequently, persons born after the swine viruses' human ancestor IAV had circulated are unlikely to have cross-reactive antibodies against the swine H3 IAVs. Therefore, with time, human population immunity against swine H3 IAVs decreases, increasing the pandemic risk (7-10).The infectious potential of swine H3 IAVs for humans is evident from >400 recorded zoonotic infections in the United States caused by North American cluster IV-A or novel human-like H3 swine IAVs. Four zoonotic infections with H3 IAVs from swine in Europe have also been reported (6,(11)(12)(13). H3 IAVs from equids can infect humans under experimental conditions, but there are no confirmed cases of natural transmission (14). Animal H3 IAVs might, however, become more adapted to humans by accumulating mutations in their viral proteins, reassortment of gene segments with IAVs of different species, or both (6,15). Avian H3 IAVs can infect humans directly or via an intermediate host, such as poultry or swine (2,15). In 2019, an H3N1 IAV that

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Gaps in Serologic Immunity against Contemporary Swine-Origin Influenza A Viruses among Healthy Individuals in the United States

Cited by 6 publications

References 40 publications

Evolution of influenza A viruses in exhibition swine and transmission to humans, 2013–2015

Evolution of influenza A viruses in exhibition swine and transmission to humans, 2013–2015

Pandemic Risk Assessment for Swine Influenza A Virus in Comparative In Vitro and In Vivo Models

Human Immunity and Susceptibility to Influenza A(H3) Viruses of Avian, Equine, and Swine Origin

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