Research Note: A recombinant duck-derived H6N2 subtype avian influenza virus can replicate and shed in young chickens and cause disease

The H6N2 subtype avian influenza virus (AIV) is commonly detected in the migratory waterfowl reservoirs. Previously, H6N2 AIV was believed to be nonpathogenic to young chickens and could not infect or shed in their respiratory tract under experimental condi-tions. However, in present study, a highly recombinant strain of duck-derived H6N2 AIV was discovered and isolated for pathogenicity tests. The results revealed that H6N2 could induce seroconversion in chickens and high morbidity of over 86.7%, along with evident upper respiratory tract hemorrhage. Moreover, 5 substitutions were detected in the upper respiratory tract shedding reisolated virus, with a high viral load in the target organs of infected chickens. In contrast, ducks failed to exhibit any symptoms, pathological lesions, or viral shedding, while demonstrated seroconversion and high viral load in the livers. These findings indicate that H6N2 AIV could also show pathogenicity to chickens under experimental conditions, thereby effectively replicating and shedding in chickens. Therefore, the study provides further elucidations on the pathogenicity of H6N2 AIV.

Automated summary

A highly recombinant strain of duck-derived H6N2 avian influenza virus (AIV) was found to cause high morbidity and respiratory tract hemorrhage in chickens under experimental conditions. The virus could effectively replicate and shed in chickens, with high viral load detected in target organs. Ducks, on the other hand, showed no symptoms or pathological lesions but had high viral load in the livers, indicating their potential role in viral transmission.