Title : Experimental infection and in-contact transmission of H9N2 avian influenza virus in crows
Abstract:
Low-pathogenicity avian influenza A (H9N2) viruses are enzootic in poultry populations in Asia and has undergone extensive genetic reassortment along with various co-circulating subtypes of avian influenza viruses, including highly pathogenic avian influenza H5N1 virus and H7N9 viruses. These mutations have permitted H9N2 virus to cross intra-species barrier to cause sporadic human infection. Herein, we have investigated the potential of H9N2 avian influenza virus to cause disease and intra-species transmission in house crows (Corvus splendens). A Group of six crows were intranasally inoculated with 106.0 EID50 of H9N2 virus A/chicken/India/01OR17/2021 and 24 hour post inoculation six naïve crows were introduced to assess in-contact transmission. Crows were observed for 14 days for any overt signs of illness. Oropharyngeal and cloacal swabs were collected up to 14 days to assess virus excretion. No apparent clinical signs were observed in either infected or in-contact crows. Virus excretion was inconsistent through oropharyngeal and cloacal routes and was observed only in infected birds up to 7 days post- infection (dpi). All six infected crows seroconverted to H9N2 virus at 14 dpi whereas all in-contact crows remained negative to H9N2 virus antibodies. At 14 dpi all crows were humanely euthanized at tissues were collected for virus isolation. No virus could be isolated from tissues viz., lung, liver, kidney, pancreas, small intestine and large intestine. Although, crows became infected with H9N2 virus however, transmission of virus was inefficient to contact group. However, virus excretion through oral and cloacal swabs from infected crows suggests a potential threat for inter-species transmission including humans. Crow being a common synanthrope species might have some role in influenza virus transmission to poultry and humans which can be explored further
