The secretory antibody response of inbred lines of chicken to avian infectious bronchitis virus infection.

Two-week-old chicks of a line highly resistant (line C) or highly susceptible (line 151) to infectious bronchitis virus (IBV) were inoculated with the Massachusetts-41 strain of IBV. Tracheal washings, saliva, lachrymal fluid and serum were collected at intervals after inoculation and titrated for their antibody content using neutralization tests and ELISAs. There was no marked difference in antibody concentrations in tracheal washings of the two lines, nor in neutralizing antibody or IBV-specific IgG titres in serum or respiratory tract secretions. However, more IBV-specific IgA was detected in both saliva and lachrymal fluid of the line C chicks following either intranasal or eyedrop inoculation. The different IgA response in lachrymal fluid, but not saliva, was also observed in another pair of inbred chicken lines of different susceptibility to IBV infection, namely lines 6, and 7(2).