IDENTIFICATION AND CHARACTERIZATION OF THE GUINEA-PIG CYTOMEGALOVIRUSGLYCOPROTEIN-H GENE

Subunit vaccines which target viral envelope glycoproteins offer promi se for the prevention of congenital cytomegalovirus (CMV) infection. T he guinea pig model of CMV infection is uniquely well suited to testin g vaccines for prevention of congenital infection, since, in contrast to other animal cytomegaloviruses, the guinea pig CMV (GPCMV) crosses the placenta, producing intrauterine infection. Antibody to the CMV gl ycoproteins B (gB) and H (gH) appears to be important in conferring pr otective immunity. Unfortunately, little is known about specific GPCMV envelope glycoproteins. Sequencing of GPCMV genome fragments was ther efore undertaken to test whether GPCMV encodes a gH homologue. Partial sequencing of the Hind III A fragment of the GPCMV genome revealed an open reading frame of 2 169 nucleotides capable of encoding a protein of 723 amino acids. Computer matrix analyses demonstrated identity be tween this ORF and the gH coding sequences of other herpesviruses. The GPCMV gH ORF encodes 12 highly conserved cysteine residues, contains 9 potential N-linked glycosylation sites, and has a predicted M(r) of 81.6 kDa. Northern blot hybridizations with gH-specific probes identif ied an abundant 5.1 kb mRNA with expression kinetics of an ''early'' g ene. A polyclonal antiserum raised against a synthetic peptide derived from the deduced amino acid sequence of the gH ORF identified a virio n-associated protein with an approximate M(r) of 85-kDa, the putative GPCMV gH, in immunoblot assays.