Neutralizing Antibodies Against St. Louis and Western Equine Encephalitic Viruses in Horses and Fowl

Abstract

It had previously been noticed that certain serums from healthy domestic fowl in California1 showed neutralizing antibodies against the Br strain of western equine encephalomyelitic virus. Serums from areas where this disease is endemic appeared to yield more positive results than those from supposedly non-endemic regions. A correlation had also been observed with human serums between the presence of antibodies for both the western equine virus and that of the St. Louis encephalitic type. About 26% of 69 serums of encephalitic patients in the Central Valley areas of California were positive to both viruses.2To determine if a similar relationship existed with animals, neutralization tests were performed on serums of domestic fowl and horses collected from endemic and presumably non-endemic areas of California.† The same technic and the same strains of virus (Br and St. Louis) were used as previously described,1 the serums being considered positive or weakly positive according to the number of virus dilutio...