Hyper-antigenic variation occurs with human rhinovirus type 17

Of 90 human rhinovirus (RV) serotypes tested, 50 can be placed into 16 groups according to antigenic relationships. It has been suggested that antigenic variants might arise in nature by immunologic pressure. To investigate this possibility, attempts were made to select variants by cloning 16 different plaque-purified RV serotypes in the presence of homologous, polyclonal antisera. Isolates were examined for evidence of variation in serum cross-neutralization tests using parental antisera and, in some cases, antisera prepared for the isolates. Only RV type 17 (RV-17) yielded major antigenic variants after cloning. With some variants, as much as a 500-fold difference in neutralizing titer was obtained with the parental antiserum. By using antisera for two of the variants, it was determined that they are prime strains of the parental RV-17. Continuing attempts at immunoselection by using antisera for one of these prime strains yielded additional antigenic variants. By using antisera prepared for three of these new variants, it was determined that one of them is a prime strain of the virus from which it was derived. Cross-neutralization tests with the two remaining isolates indicate that, according to conventional practice, they no longer would be classified as RV-17.