Maternal antibody to infectious bronchitis virus: its role in protection against infection and development of active immunity to vaccine

Chicks hatched with high levels of maternal antibody had excellent protection (> 95%) against infectious bronchitis virus (IBV) challenge at I day of age, but not at 7 days (< 30%). This protection significantly (P < 0.05) correlated with levels of local respiratory antibody and not with serum antibody. A high percentage of both maternal antibody-positive (Mab+) and maternal antibody-negative (Mab-) chicks failed to produce IBV antibody when vaccinated at 1 day of age by the intraocular route. In addition, Mabt chickens had a weaker virus-neutralizing antibody response to a second IBV vaccination compared to Mab- birds (P < 0.05). Mab+ chicks experienced a more rapid decline (P < 0.01) in maternal antibody after 1-day-of-age vaccination compared to their unvaccinated counterparts. A monoclonal antibody-based blocking ELISA that measured antibody levels specific to S1 glycoprotein of IBV correlated well with virus-neutralizing antibody titers. (C) 2001 Elsevier Science B.V. All rights reserved.