Resistance to Marek's disease. Effect of Corynebacterium parvum and Marek's tumor cell vaccines on tumorigenesis in chickens.

A study of nonspecific stimulation of the avian immune system with Corynebacterium parvum and specific stimulation with Marek's tumor cell vaccines revealed that nonspecifically stimulated outbred White Leghorn-type cockerels had higher incidences of tumors than did controls. A study of tumor cell cytotoxicity of sera from Marek's disease virus exposed birds indicated that humoral factors may play some role in tumor resistance.