THE ANTIGENIC STABILITY OF WESTERN EQUINE ENCEPHALOMYELITIS VIRUS

Abstract

Brief reference is made to studies of the homogeneity and stability of the western strain of the equine encephalomyelitis virus by testing the immunity of vaccinated animals to virus derived from as widely different sources as possible. The work gives evidence that this type of virus has not been greatly altered in its antigenic structure by transfer to guinea pigs, mice, and chicken embryos. "The fact that a vaccine gave complete protection against viruses from localities as widely separated as Iowa and Texas proves that this disease is substantially the same in different parts of the country in which it occurs. Since vaccine made with 1933 virus protects against 1937 viruses, we may be confident that vaccines made with previous years'' viruses will be effective against the disease that is now epidemic in several mid-western States and Canada.".