The effect of immunosuppression on the development of immunity to fowl typhoid.

CAMERON, C. M. , BRETT, 0. L. & FULS, W. J. P., 1974. The effect of immunosuppression on the development of immunity to fowl typhoid. Onderstepoort J. vet. Res. 41 (1), 15-22 (1974). Chickens which were given cyclophosphamide during the first three to five days of life showed a marked depression in their humoral antibody response to sheep erythrocytes and Bmcel/a antigen. Thei r ability to develop tuberculin sensitivity and their immune response to live Salmonella gallinarum vaccine was, however, unimpaired. The administration of methylprednisolone acetate, hydrocortisone acetate, azathioprim and 6-mercaptopurine to either six or 'I 0 to 12-week-old chickens neither selectively depressed the humoral or cellular immune response nor affected the immune response to liveS. gallinarum vaccine. Similarly, the immune response could not be depressed by thymectomy or antilymphocyte globulin . These results indicate that immunity to S. gal/inarum after administration of a live avirulent vaccine is not dependent on a humoral immune mechanism but probably primarily on cellular immunity, although this could not be proven.