ULTRASTRUCTURAL-STUDY OF HUMAN HERPESVIRUS-7 REPLICATION IN TISSUE-CULTURE

Human herpesvirus 7 (HHV-7) was grown in a CD4+ lymphoblastic cell lin e (SupT1) and in cord blood mononuclear cells (CBMC). Virus infection was demonstrated by immunohistology with positive control sera, with m onoclonal antibodies and by in situ hybridization for viral DNA. Cytop athic effects following HHV-7 infection generally resemble those after HHV-6 infection but are less pronounced. The ultrastructural appearan ce of HHV-7 and the replicative stages were similar to those described by Kramarsky and Sander for HHV-6. There were some minor discrepancie s, including quite an extensive and space-filling tegument, a slightly different structure of the nucleoid, the frequent finding of nucleoca psids without any visible core and apparently scarce or delicate spike s on the envelope. These differences may suggest HHV-7 rather than HHV -6, but this finding needs confirmation. Mature HHV-7 particles measur ed 170 nm in diameter, with nucleocapsids of 90-95 nm and a tegument o f about 30 nm.