Investigations into resistance of chicken lines to infection with infectious bronchitis virus

Although nine inbred and partially inbred lines of chickens were equally susceptible initially to infection with infectious bronchitis virus (IBV), the outcome of that infection varied considerably between the lines. A more detailed study of a line which was resistant (line C) and one which was highly susceptible (line 15I) confirmed that both lines could be infected initially with IBV but showed that the respiratory tract epithelium of line C chicks recovered more rapidly than that of line 15I chicks. Whereas more virus could be recovered from tissues of line 15I chicks following IBV inoculation, explants of tissues from each line inoculated in vitro appeared equally susceptible. The possibility of a different immunological response to IBV infection in the two lines is discussed and it is clear that further work is required to elucidate the mechanism involved in the differing susceptibility of the inbred chicken lines to inoculation with IBV.