Indirect immunofluorescence test for detection of IgM antibodies to cytomegalovirus

A technique for the detection of IgM antibodies to cytomegalovirus (CMV) by immunofluorescence was developed. In order to prevent interference by rheumatoid factor in the sera, IgG was removed by prior immunoabsorption with antiserum to gamma Fc. Sera from 63 patients with a rise in titer of antibody to CMV, indicated by complement fixation, were IgM-positive, but yielded negative results on the Paul-Bunnell-Davidsohn test for infectious mononucleosis. Convalescent-phase serum samples from 20 patients with a seroconversion to herpes simplex virus and from 20 patients with a seroconversion to varicella-zoster virus also had no IgM antibodies to CMV. Sera from six of 10 patients with infectious mononucleosis and two of 100 normal blood donors were positive for IgM antibodies to CMV. In 38 of 63 patients, the diagnosis of CMV infection could be made several weeks earlier by the immunofluorescence test than by the complement-fixation test. IgM antibodies to CMV persisted for more than two months after onset of symptoms of the infection.