Vesicular Stomatitis Virus—The Relationship Between Some Strains of the Indiana Serotype

Abstract

SUMMARY A number of strains of virus identified as vesicular stomatitis were examined, confirming the occurrence for the first time of outbreaks of the disease in Argentina and Brazil. For 4 strains of the virus examined the most sensitive method of assay was plaque count in BHK 21 cells, followed by intracerebral inoculation of young mice, titration in cattle and titration in pigs. The order of virulence of the strains for cattle was Ind. C, Brazil, Argentina and Cocal; and, for pigs, Ind. C and Cocal. Complement-fixation tests and cross-neutralization tests demonstrated that Argentina and Cocal strains could not be differentiated antigenically one from the other, but each differed from the Ind. C strain to the same degree as from the Brazil strain. Of the pairs examined, the Brazil and Ind. C strains were the most widely different. Cross-protection tests which were carried out in cattle by a titration method gave good correlation with the neutralizing antibody levels in the sera of the cattle used. The results indicate a degree of antigenic difference within the vesicular stomatitis virus Indiana serotype, similar to that found within the type groups of foot-and-mouth disease virus and it is proposed that the 3 antigenic groups represented by these strains be referred to as sub-types.