Because all tumors were recognized by Mab B3, C9, or both, we conclude that the mixture of Mab B3 and C9 is capable of recognizing JSRV Env in tumors caused by wild-type JSRV in multiple geographic regions, in particular, from regions where infection by either of the two major types of JSRV predominate. The gene discussed is ERVW-1; the disease is infection.