Human sera possess a limited antibody repertoire to influenza neuraminidase antigenic variants selectedin vitro

Four antigenic variants of the neuraminidase (NA) of A/Texas/77 (H3N2) virus were selected using monoclonal antibody at a frequency of one variant in 10(5) parental virions. The antigenic variants failed to react serologically with the monoclonal antibody used for their selection in vitro. The antigenic variants failed also to react serologically with a proportion of sera from children and adults although all of the sera reacted with the parental A/Texas/77 virus. Thus, certain human sera have a restricted antibody repertoire to influenza NA antigen which might enable virus antigenic variants to avoid anti-NA antibody-mediated neutralization in nature.