Characterization of a new strain of HHV-6 (HHV-6 SF) Recovered from the saliva of an HIV-infected individual

An isolate of the human herpesvirus-6 (HHV-6SF) recovered from the saliva of an HIV-infected individual differs in its cellular host range and certain genomic properties from other HHV-6 strains described. HHV-6SF replicates in adult peripheral blood mononuclear cells (PMC) substantially better than in fetal cord blood PMC and can be grown only in the MT-4 established T cell line. It preferentially infects CD4+ lymphocytes but can replicate in CD8+ cells and peripheral blood macrophages. It also infects neuroblastoma cells and cell lines derived from the gastrointestinal tract. These latter results suggest that this herpesvirus could play a role in disorders affecting these tissues. Finally, the restriction enzyme pattern of HHV-6SF differs from that of other HHV-6 strains. The identification of this distinct HHV-6 strain could indicate an unusual biologic variation among viral isolates thus far not observed with other herpesviruses.