RE-EXCRETION OF INFECTIOUS-BRONCHITIS VIRUS IN CHICKENS INDUCED BY CYCLOSPORINE

Following inoculation of day-old chicks with Moroccan strain 'G' of in fectious bronchitis virus (IBV) which has a predilection for the gut, virus was recovered from the trachea up to day 7 and from the cloaca u p to day 35. After this no virus could be detected, even following the natural stress of re-housing with unfamiliar birds at 9 weeks. When t he birds were 12.5 weeks old, they were injected with cyclosporin, a s elective T-cell suppressor. Four of the five birds re-excreted virus v ery erratically, as did two of five contacts. This was accompanied by the appearance of IBV-specific IgM in the sera of both groups. The res ults suggest that in long-term infections with IBV, virus persistence is controlled by T lymphocytes.