Characteristics of Echo 4 (Shropshire) Virus Isolated during Epidemic of Aseptic Meningitis

Summary Neutralization tests using hyperimmune monkey antisera or human sera in test tube cultures or by plaque reduction demonstrated antigenic similarity between the Buffalo strains as represented by Shropshire and the prototype ECHO 4 virus. The viruses could be distinguished serologically by the same methods using hyperimmune antisera prepared in rabbits. ECHO 4 antibody response in patients was measured by two methods: a) tube tissue culture neutralization tests employing strain DuToit which was found to be well neutralized by ECHO 4 antibody, and b) plaque reduction tests using either Shropshire or prototype ECHO 4 virus.