A description by Cotton 1-3 of the circumstances in which the virus of vesicular stomatitis (VS) was isolated in the U.S. in 1925 serves to confirm that little has changed in the disease pattern of VS in cattle over the past 60 years. A carload of apparently healthy animals shipped from Kansas City to Richmond, Ind. developed lesions of the tongue and buccal mucosa following distribution to individual farms and an infectious agent was isolated. The disease was found also to affect horses. The next year a large outbreak of VS occurred in New Jersey, affecting over 750 cattle and 12 horses. The presence of teat lesions in three herds and foot lesions in some animals was ascribed by Cotton to an unusually virulent strain of virus. He reported that there were two distinct strains, “each of which will immunize against itself but neither will immunize against the other.” 3 The two strains were subsequently designated VS Indiana (VSI) and VS New Jersey (VSNJ) after the localities in which they were isolated.