Syngeneic CD8+ T lymphocytes protect chicks from acute infectious bronchitis viral infections and' respiratory illness

Respiratory illness could be observed following IBV inoculation of chicks with the all of the haplotypes examined, but susceptibility to respiratory illness and kinetics of recovery differed. Chicks with B-12/B-12 and B-19/B-19 were most susceptible to respiratory illness and recovered more slowly than B-2/B-2 and B-5/B-5 chicks. Adoptive transfer studies with syngeneic chicks were used to confirm the importance of CD8(+) T cells in protection against IBV. As determined by respiratory illness and viral load, administration of primary effector donor T-lymphocytes protected chicks from challenge infection in a dose-dependent manner,, whereas no protection was observed in the chicks receiving the syngeneic lymphocytes from uninfected chicks. Protection following administration of T lymphocytes could be observed regardless of the haplotype of the chicks. Fractionation of lymphocytes with phenotype-specific antibody indicated that protection was dependent on CD8(+)alphabeta T lymphocytes. Protection from donor immune cells collected 3 weeks p.i. was decreased compared to primary effector cells collected at 10 days p.i. Observed memory function in infected syngeneic chicks increased between 3 and 6 weeks p.i. and was dependent on the dose of immune T-cells transferred.