H9N2 Viruses Isolated From Mammals Replicated in Mice at Higher Levels Than Avian-Origin Viruses

Abstract

H9N2 subtype influenza A virus (IAV) has more than 20 genotypes that are able to cross species barriers and expand from birds to mammals and humans. To better understand the impact of different H9N2 genotypes and their characteristics, five H9N2 viruses from different hosts including chickens, geese, pigs, mink, and humans representing the B69 88(Gs/14, Ck/15, and Mi/14), B35 (Sw/08) and G9 genotypes (Hu/04) were infected in chicken and mice. In mice, mammal-origin viruses replicated at higher levels in the lungs compared to avian viruses. The goose-virus replicated at the lowest levels indicating poor adaptation. Increased pro-inflammatory cytokines were positively correlated with viral loads in the lung. In chickens, all viruses were excreted from cloacal and/or oropharyngeal swabs. Interestingly, Mink-origin virus exhibited higher virulence and replication in mice and chickens. Our data indicate that mammal-origin H9N2 viruses are more adapted and virulent in mice than the avian-origin viruses.

Egyptian Fruit Bats (Rousettus aegyptiacus) Were Resistant to Experimental Inoculation with Avian-Origin Influenza A Virus of Subtype H9N2, But Are Susceptible to Experimental Infection with Bat-Borne H9N2 Virus

“…In 1999, the first isolation of H9N2 from two diseased children in Hong Kong was published [ 6 ]. In addition, H9N2 viruses are able to replicate in further mammalian species, such as pigs or mice [ 7 ]. Multiple cases of H9N2 outbreaks in avian species in Africa have been reported inter alia from Egypt [ 8 , 9 ], where the virus is endemic [ 2 ].…”

Effect of enrofloxacin on clinical parameters and mucociliary system of broilers challenged with H9N2 avian influenza/infectious bronchitis viruses

“…It has been demonstrated that IBV results in the loss of goblet cells in the tracheal mucosa of chickens (Nakamura et al., 1991 ); on the contrary, Sun et al. ( 2019 ) showed that H9N2 viruses induce a severe increase of goblet cells in the trachea of infected chickens. Therefore, the increased number of tracheal goblet cells which was observed from day 3 in infected groups of our study can be related to H9N2 but not IB infection.…”

Human‐infecting influenza A (H9N2) virus: A forgotten potential pandemic strain?

“…It has been found that G1‐lineage of H9N2 viruses circulating in poultry in Middle East regions possessed high prevalence of mutations in PB2 coffering enhanced replication and growth in mammals, which may pose public health risks beyond the current outbreaks (Arai et al, ). Recent study demonstrated that H9N2 virus isolated from mammalian hosts showed enhanced replication capability in mice, suggesting mammalian‐origin H9N2 viruses were more adapted and virulent than that of avian‐origin viruses (Sun et al, ). Rapid selection of avian H9N2 virus with reduced susceptibility to neuraminidase inhibitors oseltamivir and zanamivir after 1–2 passages in the egg implied that antivirals may be less useful in clinics if it should have sparked the pandemics (Kode et al, ).…”