NUCLEOTIDE-SEQUENCE ANALYSIS OF A 30-KILOBASE-PAIR REGION OF HUMAN HERPESVIRUS-6B (HHV-6B) GENOME AND STRAIN-SPECIFIC VARIATIONS IN MAJOR IMMEDIATE-EARLY GENES

Human herpesvirus 6 (HHV-6) is now classified into two distinct varian ts such as HHV-6 variant A(HHV-6A) and B(HHV-6B) (Ablashi et al., Arch . Virol. 129, 1993, 1-4) and the DNA of HHV-6A strain U1102 was comple tely sequenced (Gompels et al., Virology 209, 1995, 29-51). We have se quenced a 30-kilobase pair (kbp) (genomic positions around 111-141 kb) of HHV-6B strain HST, and a sequence of this region was compared with that of HHV-6A strain U1102. Dodecameric repeats, G/T and Kpn repeat elements, putative major immediate early 1 (MIE1) and major immediate early 2 (MIE2) genes were found in this region. The DNA sequences of H HV-6A (U1102) and HHV-6B (HSI) were markedly different in the MIE1 reg ion, Kpn repeat elements and the putative MIE2 region. Dodecameric rep eat element was located in the putative MIE2 locus of HHV-6. When prim ers covering dodecameric repeat region were used to amplify HHV-6 DNA of clinical isolates from patients with exanthem subitum (ES) by polym erase chain reaction (PCR), Variations in size of PCR products in each isolate were found: indicating strain-specific features. Furthermore, the results of molecular biological analysis by PCR using DNA samples in a family suggest that HHV-6 infects within a family. (C) 1997 Else vier Science B.V.