SYSTEMIC AND LOCAL ANTIBODY-RESPONSES TO INFECTIOUS-BRONCHITIS VIRUS IN CHICKENS INOCULATED WITH INFECTIOUS BURSAL DISEASE VIRUS AND CONTROL CHICKENS

Serum and local (respiratory) antibody responses to infectious bronchi tis virus (IBV) were studied in 5-wk-old white leghorn-type control ch ickens and chickens inoculated with infectious bursal disease virus (I BDV) at 1 day of age. Of the chickens inoculated with IBV alone, 93% h ad detectable levels of IBV antibodies in the sera and 87% had detecta ble antibodies in the respiratory lavage fluids. Compared to this grou p, only 73% and 65% of IBDV-IBV inoculated chickens had serum and resp iratory antibodies, respectively In chickens inoculated with IBV alone , the IBV antibodies were evenly associated with immunoglobulin classe s IgM, IgG, and IgA, whereas the IBDV-IBV inoculated chickens mainly p roduced IgM-associated antibodies with low to negligible levels of IgA - and IgG-associated antibodies. These results suggest that the lack o f adequate IgA- and IgG-associated antibody production in IBDV-infecte d chickens may account for their increased susceptibility to IBV infec tion.