Abstract
A small polypeptide from pUL57 of human cytomegalovirus was identified as a major target for the immunoglobulin M antibody response. This antigen seems to be superior to antigenic fragments from pp150 and p52 in the identification of sera from acutely infected patients. It may therefore represent an essential antigen for recombinant immunoglobulin M antibody tests for human cytomegalovirus.