West Nile virus infection in American singer canaries: An experimental model in a highly susceptible avian species

This study investigated the susceptibility of American singer canaries (Serinus canaria) to West Nile virus (WNV) infection. Adult canaries were inoculated with 10⁵, 10², and 10¹plaque forming units (PFU) of WNV. All birds became infected and mortality occurred by 5 days postinoculation. The load of viral RNA as determined by RT-qPCR was dose dependent, and was higher at all doses than the level of viral RNA detected in American crows (Corvus brachyrhynchos) challenged with 10⁵ PFU of WNV. In a subset of birds, viremia was detected by virus isolation; canaries inoculated with 10¹ PFU of WNV developed viremia exceeding 10¹⁰ PFU/mL serum, a log higher than American crows inoculated with 10⁵ PFU of virus. In canaries euthanized at 3 days postinoculation, WNV was isolated at >10⁷ PFU of virus/100 mg of lung, liver, heart, spleen, and kidney tissues. Pallor of the liver and splenomegaly were the most common macroscopic observations and histologic lesions were most severe in liver, spleen, and kidney, particularly in canaries challenged with 10² and 10¹ PFU. Immunoreactivity to WNV was pronounced in the liver and spleen. IgG antibodies to WNV were detected in serum by enzyme immunoassay in 11 of 21 (52%) challenged canaries and, in 4 of 5 (20%) of these sera, neutralization antibodies were detected at a titer ≥ 1:20. American singer canaries provide a useful model as this bird species is highly susceptible to WNV infection.