The Vaccinial Infection of Fowls of Different Ages in Relation to the Antiviral Power of the Blood *

It is known that paralleling the growth of fowls antibody-like factors against many bacteria and foreign cells appear regularly in their blood.' 5, 6 Cancer-inducing viruses are also affected by similar factors.7 The viruses of the Rous and Fuginami sarcoma and of the Mill Hill 2 endothelioma are strongly neutralized by the serum of adult fowls, but the Rous virus, the only one studied in this respect, is generally not affected by the serum of chicks and pullets. It was thought desirable to extend these observations to vaccinia, the virus which induces active cell proliferation promptly followed by necrosis. Levaditi and Nicolau"3 showed that dermovaccine virus adapted to the brain of rabbits (neurovaccine) has lost most of its power to infect chickens. Andervont2 confirmed this observation, but showed that chicks are susceptible to neurovaccine injected into the skin. Chicks die after intracerebral injections of vaccinia and the virus can be passed serially through the brain of chicks. Buddingh4 has described the generalized lesions occurring in chick embryos injected in the chorio-allantois. With the exception of the central nervous system the virus disseminated throughout the whole organism with no evidence of heightened affinity for any special tissue. Guarnieri-like bodies were formed in all the lesions.