EVALUATION OF A COMMERCIAL ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR DETECTION OF SERUM IMMUNOGLOBULIN-G RESPONSE TO HUMAN-HERPESVIRUS-6

A rapid (60-min) commercially available enzyme-linked immunosorbent as say (ELISA) for the detection of immunoglobulin G (IgG) class antibodi es to human herpesvirus 6 (HHV-6) was evaluated, The specificity of th e ELISA for HHV-6 was confirmed by absorption studies, with the reacti vities of HHV-6-positive sera being unaffected by other herpesviruses (cytomegalovirus, herpes simplex virus, and varicella-zoster virus) or the HSB2 cell line used to culture HHV-6. HHV-6 IgG antibody levels i n a panel of 502 serum samples were determined by ELISA and an indirec t immunofluorescence assay (IFA). Results obtained by the two methods were in close agreement, suggesting that the ELISA provides a suitable test method for the determination of HHV-6 IgG antibodies in a routin e clinical laboratory. Both tests were positive in 398 cases (79%), an d both were negative in 71 cases (14%), with a different result obtain ed by IFA and ELISA in only 33 cases (7%). Furthermore, absorption of sera with HHV-6 prior to assay revealed that the majority of these res ults were false positive (n = 8) or false negative (n = 23) in the IFA (true positives or negatives in the ELISA). Subsequently, the ELISA s howed a sensitivity of 99.76% and a specificity of 98.75%. HHV-6-speci fic IgG levels were also determined in paired serum samples collected from 49 donors-14 with exanthem subitum (ES), 15 with ES which was com plicated with central nervous system involvement, and 20 undergoing bo ne marrow transplantation-in whom HHV-6 infection had been demonstrate d by virus isolation and/or PCR, All patients with ES or central nervo us system complications showed an increase in HHV-6-specific IgG, indi cating that this ELISA may be a useful aid in the diagnosis of these c onditions. Furthermore, 14 of 20 patients undergoing bone marrow trans plantation showed an increase in HHV-6-specific IgG levels, possibly r eflecting a reactivation of HHV-6 in these patients.