Experimental Infection of the Chick Embryo with the Virus of Pseudorabies

The chick embryo responds to experimental infection with the virus of pseudorabies with a disease pattern simulating the natural infection. Virus lesions of the membrane are followed by infection of all tissues of the central nervous system. Fixed strains produce a hemorrhagic destruction of the central nervous system of the embryo, which is referable to destruction of blood vessel endothelium. Field strains lack the hemorrhagic tendency, but infect the brain when inoculated on the membrane. Neutralization of the virus by specific hyperimmune serum can be demonstrated by inoculation on the membrane. The reaction of the embryo to the virus varies with the age of the embryo. This is reflected both in the membranal lesion and in the subsequent encephalitis.