RESTRICTION-ENDONUCLEASE MAPPING AND MOLECULAR-CLONING OF THE HUMAN-HERPESVIRUS-6 VARIANT-B STRAIN Z29 GENOME

Human herpesvirus 6 (HHV-6) variants A and B differ in cell tropism, r eactivity with monoclonal antibodies, restriction endonuclease profile s, and epidemiology. Nonetheless, comparative nucleotide and amino aci d sequences from several genes indicate that the viruses are very high ly conserved genetically. The B variant is the major etiologic agent o f exanthem subitum and is frequently isolated from children with febri le illness; no disease has been etiologically associated with HHV-6A. One HHV-6A strain has been cloned and sequenced, but similar informati on and reagents are not available for HHV-6B. We report here the deter mination of maps of the restriction endonuclease cleavage sites for Ba mHI, ClaI, HindIII, KpnI, and SalI, and the cloning in plasmids and ba cteriophages of fragments representing over 95% of the HHV-6B strain Z 29 [HHV-6B(Z29)] genome. Hybridization experiments and orientation of several blocks of nucleotide sequence information onto the genomic map indicate that HHV-6A and HHV-6B genomes are colinear.