The antigenic structure of a human influenza A (H1N1) virus isolate grown exclusively in MDCK cells.

A panel of monoclonal antibodies has been produced against a 1983 human influenza A (H1N1) virus that has been isolated and grown exclusively in MDCK cells. Several of these antibodies were used to select variants from MDCK-derived virus in cells and their epitopes were then located by determining the HA1 amino acid sequence. The operational antigenic map of the haemagglutinin indicates the presence of two distinct immunodominant antigenic regions which correspond but are not identical to antigenic sites Sa and Sb of the A (H1N1) virus A/PR/8/34. Also during this study, we characterized a unique group of antibodies for which variants require two distinct and specific HA1 amino acid substitutions to escape neutralization.