Antigenic analysis of human herpesvirus 7 (HHV-7) and HHV-6 using immune sera and monoclonal antibodies against HHV-7

Using polyclonal and monoclonal (MAbs) antibodies to human herpesvirus 7 (HHV-7), we have studied HHV-7-specific polypeptides, Human sera were obtained during the convalescent phase from patients with exanthem subitum due to HHV-7, and at least 16 HHV-7-specific polypeptides with apparent molecular masses of 26-210 kDa were immunoprecipitated, Sera prepared in mice also precipitated at least 17 HHV-7-specific polypeptides with molecular masses of 26-210 kDa, Among them, the most commonly observed antigenic protein had an apparent molecular mass of 52 kDa, Forty-two clones secreting MAbs against HHV-7-specific proteins, as determined by immunofluorescence assays, were established from BALB/c mice immunized with HHV-7-infected cell extracts, Seven MAbs which immunoprecipitated HHV-7-specific polypeptides were further characterized, Two of these, MAbs 5E12 and 5F12, reacted predominantly with glycoproteins of 78 kDa and 85 kDa, respectively, and possessed neutralizing activity, This suggests that there are at least two neutralization-inducing proteins in HHV-7, MAb 16B4 reacted with the major immunogenic protein of 52 kDa, Five of the 42 MAbs also reacted in immunofluorescence assays with HHV-6 antigens to the same degree as to HHV-7, Two other MAbs, 7C10 and 10F1, recognized an HHV-7 protein of 40 kDa, and only 7C10 cross-reacted with an HHV-6 protein of 45 kDa.