The comparison of pathology in ferrets infected by H9N2 avian influenza viruses with different genomic features

Abstract

H9N2 avian influenza virus circulates widely in poultry and has been responsible for sporadic human infections in several regions. Few studies have been conducted on the pathogenicity of H9N2 AIV isolates that have different genomic features. We compared the pathology induced by a novel reassortant H9N2 virus and two currently circulating H9N2 viruses that have different genomic features in ferrets. The results showed that the three viruses can induce infections with various amounts of viral shedding in ferrets. The novel H9N2 induced respiratory infection, but no pathological lesions were observed in lung tissues. The other two viruses induced mild to intermediate pathological lesions in lung tissues, although the clinical signs presented mildly in ferrets. The pathological lesions presented a diversity consistent with viral replication in ferrets.

H9 Influenza Viruses: An Emerging Challenge

“…Ferrets inoculated with field H9N2 isolates show mild clinical signs with the infection confined mostly to the upper respiratory tract (Wan et al 2008). In contrast, ferrets inoculated with H9Nx avian/ mammalian reassortants produce clinical signs and lung pathology associated with moderate to severe broncho-interstitial pneumonia, consistent with macrophages, lymphocyte and neutrophil infiltrations, alveolar edema, and rupture (Wan et al 2008;Sorrell et al 2009;Kimble et al 2011Kimble et al , 2014Gao et al 2016). Recently, tree shrews have been proposed as an alternative to ferret and nonhuman primate models, being evolutionarily closer to humans.…”

Endemicity of H9N2 and H5N1 avian influenza viruses in poultry in China poses a serious threat to poultry industry and public health

“…Experimental studies also have shown that domestic cats and dogs are susceptible to H9N2 AIVs [101,102] , thus may serve as host species contributing to the adaptation of H9N2 viruses in mammals. In ferrets, H9N2 infection results in high replication and efficient transmission by direct contact [103] and leads to mild to moderate lesions in lung tissue when infected by H9N2 AIVs with different genomic features [104] . In guinea-pigs, the H9N2 virus was restricted to the respiratory system and shed at high titers through the nasal tracts [105] .…”

Landscape genetics of avian influenza (H5N1 and H9N2) in Egyptian poultry from 2006-2015

“…Since 2010, two subtypes of influenza have circulated in Egyptian poultry and wild birds, H5N1 and H9N2 [4]. H9N2, while less deadly than H5N1, can and does infect humans, and is also considered a pandemic candidate [23].…”

“…can cause serious illness, and recent isolates of avian H9N2 have shown mutations which improve binding with human cells [23].…”

“…It has also been suggested H9N2, a low pathogenic avian influenza (LPAI) virus, which emerged in 1994, may be an equally plausible candidate for the next pandemic virus [5,28]. H9N2 viruses are endemic in poultry across a wide geographic range, have caused infections in humans and pigs, and are, at least in some cases, partially adapted to recognize and bind to human receptors [23,29]. It is conceivable co-infection with H5N1 and H9N2 could produce a new subtype capable of infecting humans with high pathogenicity.…”