THE USE OF LABELED FUSION PROTEIN FOR DETECTION OF B-19-PARVOVIRUS IGM ANTIBODIES BY AN IMMUNOCAPTURE TEST

A new anti-B19 IgM ELISA was developed taking advantage of antibody-capture with biotinylated fusion protein as antigen. Specificity was examined using serum IgM antibody positive for rubella, hepatitis B core antigen, cytomegalovirus and Epstein-Barr virus as with sera positive for rheumatoid factors or antinuclear antibodies. The specificity was found to be 96%. Of one hundred serum samples compared using the new ELISA or the standard MACRIA tests for the presence of B19 IgM, 88 gave the same results. Fifty-three were negative and 35 were positive. Six sera were ELISA-negative MACRIA-positive, and six MACRIAnegative ELISA-positive. Thus, the ELISA gave 90% agreement with MACRIA. In a clinical study with 725 sera from suspected B19 infections, 161 (22%) were found positive by ELISA. The positive sera were from patients suffering from arthritis (35%), rash (35%), acute or chronic erythroblastopenia (21%), pancytopenia (5%), vascular purpura (2%) and lymphadenopathy (2%). A series of serum specimens obtained from two-B19 infected individuals were also studied. The IgM antibody became undetectable after four months.