Immunocompetence of chickens during early and tumorigenic stages of Rous-associated virus-1 infection.

A study was designed to determine the effects of congenital infection with the Rous-associated virus-1 (RAV-1) on the immune function chickens during the early and late tumorigenic stages of infection. In another experiment, the effects of niridazole on the immune competence and the tumor incidence in chickens congenitally infected with RAV-1 were studied. Lymphocyte stimulation by phytohemagglutinin, the phytohemagglutinin skin test, the response to immunization with sheep erythrocytes and Brucella abortus, and histological evaluation of lymphoid organs were used to determine the immune competence in normal and infected chickens. Results indicated that both B- and T-cell immune functions during the early and late stages of RAV-1 infection were comparable to those of normal uninfected chickens. Administration of niridazole to congenitally infected chickens at 5 weeks of age for 7 or 21 days had no effect on the T-cell-mediated immunity; however, administration of the drug for 21 days eliminated lymphoma development. Unlike infection with other oncogenic viruses such as those causing Marek's disease and reticuloendotheliosis, infection with RAV-1 caused no detectable immunodepression during the early and late stages of infection.