EVALUATION OF A NOVEL IMMUNOGLOBULIN-A CAPTURE ENZYME-IMMUNOASSAY FORDIAGNOSIS OF CYTOMEGALOVIRUS-INFECTION IN RENAL AND HEART-TRANSPLANT RECIPIENTS

In a retrospective cohort study of 68 organ transplant patients, the u sefulness of a new commercial immunoglobulin A (IgA) antibody capture enzyme immunoassay (EIA) specific to human cytomegalovirus (CMV) for t he early diagnosis of CMV disease was investigated. The results were c ompared with those obtained with the CMV pp65 antigen assay in periphe ral blood leukocytes, an IgM immunoblot assay, and six other commercia l EIAs. In 21 of 28 patients with CMV disease, the pp65 antigen assay and the immunoblot assay identified patients before the onset of disea se more frequently than any other serological test method (17 and 13 p atients, respectively; p = 0.0029). In patients at risk for primary CM V infection, the pp65 antigen assay was the only method that identifie d all patients prior to the onset of CMV disease (p = 0.008), For the other patients who were at risk for CMV infection, the pp65 antigen as say and the immunoblot assay detected infection before CMV disease mor e frequently than any other test system (p = 0.026), With respect to C MV disease, both immunoblotting and the pp65 antigen assay showed exce llent sensitivity (100% and 89%, respectively). However, the specifici ty of the immunoblot was poor (41%), while the specificity of the pp65 antigen assay was reasonably good (68%), The IgA capture EIA showed m oderate sensitivity (61%) and reasonable specificity (76%), In conclus ion, the pp65 antigen assay, which detects pp65 antigen in leukocytes, is the method of choice for diagnosis of either primary or recurrent CMV infection. The specificity of the pp65 antigen assay was improved by additional testing for specific IgA and IgM antibodies (95% vs. 68% ). The IgA assay is of limited value in renal and heart transplant pat ients, since it detected IgA antibodies only sporadically, and even th en, too late for a timely therapy.