Abstract
Biological and serological comparisons of sequential isolates of Coxsackie A16 virus (Cox A16) in 1951 through 1970 were made to elucidate the mode of appearance of the mutant which caused a nationwide epidemic of hand-foot-and-mouth disease (HFMD) in 1970. Most strains isolated from feces of healthy children in 1964, 1966 and 1967 were serologically similar to the prototype strain isolated in 1951. However, some strains isolated from these healthy children in 1966 and 1967 were serologically and biologically related more closely to the epidemic strain isolated in 1970. Thus sequential isolates of Cox A16 could be roughly classified into two groups, i.e., the prototype strain-like and the epidemic strain-like groups.
