EPITOPE MAPPING OF CROSS-REACTIVE MONOCLONAL-ANTIBODIES SPECIFIC FOR THE INFLUENZA-A VIRUS PA AND PB2 POLYPEPTIDES

Characterization of the epitopes recognized by 21 monoclonal antibodie s (MAbs) specific for the influenza A virus PA (13 MAbs) and PB2 (8 MA bs) polypeptides (Barcena et al. (1994) J. Virol. 68, 6900-6909) raise d against denatured polypeptides produced in E. coli is described. MAb s were characterized by: (1) competitive binding ELISAs; (2) mapping o f the protein regions that specify their binding sites; and (3) analys es of their ability to recognize the corresponding viral protein in a number of viral isolates. Five and three non-overlapping antigenic are as were defined by the anti-PA and anti-PB2 MAbs, respectively. Five o f the anti-PA MAbs recognized antigenic determinants located within th e amino-terminal 157 amino acids of the PA protein, and 6 others react ed strongly with a PA fragment comprising the first 236 amino acids. A ll 8 anti-PB2 antibodies reacted strongly with a polypeptide fragment containing amino acids 1-113 of the PB2 protein. Analyses of the react ivities of 4 anti-P antibodies with 23 influenza A virus reference str ains isolated over a period of 61 years and recovered from humans, pig s, birds and horses, showed that the epitopes were conserved among all viral isolates. The application of these antibodies as research and d iagnostic tools is discussed.