Reactivity to p52 and CM2 recombinant proteins in primary human cytomegalovirus infection with a microparticle agglutination assay

We evaluated the reactivities of sera against p52 and CM2 recombinant antig ens of human cytomegalovirus (HCMV), coated on microparticles, for the diff erentiation of primary HCMV infection from an established infection. Two di fferent test formats of the CMV Multiplex Copalis assay were evaluated. The 214 serum samples tested were immunoglobulin M (IgM) positive or equivocal by our reference assay. Reactivities against p52 and CM2 antigens were tes ted for sera from 37 patients with a well-documented seroconversion within the preceding 3 months (119 serum specimens), 31 patients known to have had a seroconversion at least 8 months earlier (31 serum specimens), and 57 pa tients without a documented seroconversion (64 serum specimens). The assay had a sensitivity for the detection of a primary infection of 70 or 86% by the first test format and a sensitivity of 88 or 94% by the second test for mat, according to the criteria used to indicate a primary infection by this test. A good correlation of the results of the assay with our in-house avi dity index was found. The specificity of the assay warrants further evaluat ion. With IgM-positive sera, the assay was not sufficiently specific to mak e a distinction betffeen a primary infection and an established infection.