CHARACTERIZATION OF GLYCOPROTEIN-H AND GLYCOPROTEIN-L OF HUMAN HERPESVIRUS-7

The genes encoding the glycoproteins H (gH) and L (gL) of human herpes virus 7 (HHV-7) have been identified. The gH open reading frame (ORF) was 2,070 base pairs in length and encoded a predicted 690 amino-acid protein. The gH contained characteristics of a transmembrane glycoprot ein including 10 consensus N-linked glycosylation sites, 12 cysteine r esidues, a potential amino-terminal signal sequence and a predicted tr ansmembrane segment located near the carboxyl terminus, The gL ORF was 738 base pairs in length and encoded a predicted 246 amino-acid prote in, Four possible N-glycosylation sites and 6 cysteine residues existe d within gL, The predicted amino-acid sequences of the HHV-7 gH and hu man herpesvirus 6 variant A (HHV-6A) gH gene products exhibited 23.6% identity to each other, and those of the gL gene products had 26.0% id entity, Upon in vitro translation of the gL gene, the addition of micr osomal membranes resulted in two modified products with molecular weig hts of 32 kDa and 35 kDa from the unmodified initial translation produ ct of 26 kDa, An amino-terminal portion of gH and the full length of g L were expressed as glutathione S-transferase fusion proteins, and the se proteins were used to raise immune sera in mice, Lysates of cells i nfected with HHV-7 were subjected to immunoprecipitation analysis, App roximate molecular weights of 33, 37, 80 and 90 kDa polypeptides were immunoprecipitated with antibodies against the gH protein, Antibodies against the gL protein polypeptides with the same molecular weights we re also precipitated, and were observed with the antibodies against th e gH protein, These results suggest that HHV-7 gH and gL may form a he terodimeric complex with each other in HHV-7 infected cells, as has be en reported for other herpesviruses.