Comparison between immunofluorescence and enzyme-linked-immunosorbent assay in the determination of serum HHV-6 IgG

546 human sera from healthy subjects, subjects with cytomegalovirus or Epstein-Barr virus infection and from cordal blood were tested for the human herpesvirus-6 (HHV-6) IgG content in an enzyme-linked immunosorbent assay (ELISA) to verify results previously obtained with an immunofluorescence assay (IFA). The HHV-6 isolate CV, obtained from a child with exanthem subitum, employed as antigen in both tests, belonged to HHV-6 variant B. The ELISA results were similar to those obtained with IFA. 445/546 (81.5%) sera had the same type of reactivity with the two serological procedures. To establish whether different HHV-6 strains may give different serological results, 117 out of the 546 sera tested with IFA against CV infected cells were also tested against cells infected with the HHV-6 isolate U1102 belonging to variant A. All the sera showed a similar reactivity.