Epitope mapping of antibodies recognising the N-terminal domain of simian virus large tumour antigen.

The large tumour antigen (TAg) of simian virus 40 is the main regulatory protein in viral replication. We have investigated possible functional roles for the N-terminal domain of TAg while defining the epitopes of antibodies binding within that region. The epitopes recognised by eight monoclonal anti-TAg antibodies were identified using synthetic peptides in an enzyme-linked immunosorbent assay. For antibodies PAb 223, 281, 211, 219 and 224, epitopes varied in length between ten and fifteen amino acids. Two antibodies, PAb 210 and PAb 419, could not be mapped any further using this technique. Antibody PAb 416 recognised a pentapeptide WEQWW that could be involved in topoisomerase I binding and possibly in the interaction between topoisomerase I and simian virus reverse transcriptase.