Epitope mapping of the influenza A virus RNA polymerase PA using monoclonal antibodies

To obtain reagents to functionally map the PA protein, we produced monoclon al antibodies specific to this protein. Twenty-two monoclonal antibodies re acting with PA protein in ELISA were divided into 10 groups on the basis of competitive binding patterns to this protein. Of these, seventeen monoclon al antibodies bound to PA polypeptide spanning amino acids 101-400 and thre e bound to that of amino acids 518-600, while the other two did not react w ith any PA polypeptides tested with the exception of full-length PA. Among these monoclonal antibodies, only five reacted with PA in A/PR/8/34 virus-i nfected cells in indirect immunofluorescence assay. Thus, we obtained monoc lonal antibodies that recognize at least 10 distinct regions of the PA mole cule. These monoclonal antibodies should be useful in dissecting functions of the PA protein.