Antibody Response and Viral Shedding Profile of Egyptian Geese (Alopochen aegyptiacus) Infected with Low Pathogenicity H7N1 and H6N8 Avian Influenza Viruses

Abstract

Egyptian geese (Alopochen aegypticus), a duck species endemic to sub-Saharan Africa and occasionally implicated in the transmission of avian influenza viruses (AIV) to farmed ostriches, were experimentally infected with low pathogenicity H7N1 and H6N8 viruses to assess viral shedding and immune profiles. Following the first infection with H7N1 virus, high titers of virus were shed from both the tracheae and cloacae for at least 7 days postinfection, and tracheal shedding lasting until day 14. All detectable shedding from both tracheae and cloacae had ceased within 28 days of infection. Antibody titers peaked at day 7 postinfection, but the initial immune response was short-lived. Birds that received a second challenge with the homologous H7N1 virus mounted a more robust response that lasted beyond 66 days postchallenge, and H7N1 virus was detected, albeit at much lower levels, until day 28 post secondary infection (psi) in the cloaca and beyond day 28 psi in the trachea. Birds that received an initial infection with H7N1 virus were also challenged with H6N8 virus, and because a comparable shedding pattern to the H7N1 challenge group was observed, we concluded that the effect of any nonspecific immunity was negligible.