Swine Influenza Virus (H1N2) Characterization and Transmission in Ferrets, Chile

Abstract

Phylogenetic analysis of the influenza hemagglutinin gene (HA) has suggested that commercial pigs in Chile harbor unique human seasonal H1-like influenza viruses, but further information, including characterization of these viruses, was unavailable. We isolated influenza virus (H1N2) from a swine in a backyard production farm in Central Chile and demonstrated that the HA gene was identical to that in a previous report. Its HA and neuraminidase genes were most similar to human H1 and N2 viruses from the early 1990s and internal segments were similar to influenza A(H1N1)pdm09 virus. The virus replicated efficiently in vitro and in vivo and transmitted in ferrets by respiratory droplet. Antigenically, it was distinct from other swine viruses. Hemagglutination inhibition analysis suggested that antibody titers to the swine Chilean H1N2 virus were decreased in persons born after 1990. Further studies are needed to characterize the potential risk to humans, as well as the ecology of influenza in swine in South America.

Interspecies Transmission of Reassortant Swine Influenza A Virus Containing Genes from Swine Influenza A(H1N1)pdm09 and A(H1N2) Viruses

“…In contrast, an H1N2 strain from South Korea that had the pH1N1 internal gene cassette was found to infect directly inoculated and contact ferrets and also be transmitted at a lower efficiency, to ferrets indirectly exposed to airborne respiratory droplets (42). In a similar fashion, an H1N2 reassortant strain from Chile containing the pH1N1 internal gene cassette was also transmitted between ferrets by direct and indirect routes (19).…”

“…One such H1H2 reassortant gave rise to a human clinical case of influenza in a worker on a swine farm (18). A reassortant H1N2 virus strain was also isolated from pigs in Chile; this virus incorporated human-origin HA and NA gene segments prevalent in the 1990s and the pH1N1 internal gene cassette (19). Human infection with swine-origin H1N2 viruses (H1N2v infection) has been reported in the United States, most notable being 3 human influenza cases linked to infection with a related co-circulating H1N2 swine IAV virus incorporating a pH1N1-origin M gene segment (20).…”

Backyard poultry production in Chile: animal health management and contribution to food access in an upper middle-income country

“…Concerningly, Bravo-Vasquez et al (2016) identified the presence of influenza A virus in BPS in central Chile, with seroprevalence ranging from 42 to 60% at BPS level while Jimenez-Bluhm et al (2018a) found that influenza virus positivity by real-time RT-PCR (qRTPCR) ranged from 0% to 45.8% at the farm level. Furthermore, influenza virus has been isolated in pigs in BPS in Chile; results that are very interesting as the isolated virus was a swine-human reassortant that could represent a potential threat to public health (Bravo-Vasquez et al, 2017). Hence, not only the productive systems may be in risk, but also public health.…”

Antigenic characterization of novel H1 influenza A viruses in swine

“…The HA segments of these Chilean IAVs were likely introduced into swine from humans in the late 1980s and early 1990s 24 . Hence, these viruses evolved in the swine population for over two decades, and now they are genetically distant from other human IAVs described worldwide [24][25][26] . Moreover, these Chilean strains have unique glycosylation site patterns, which were not detected in human IAV strains 20 .…”