Summary auto-generated
Researchers identified and characterized the gene encoding glycoprotein B (gB) of rhesus cytomegalovirus (RhCMV), which is highly homologous to human cytomegalovirus (HCMV) gB. The RhCMV gB gene encodes an 854-amino acid protein with 60% identity and 75% similarity to HCMV gB. The protein contains structural features typical of membrane glycoproteins, including signal and anchor sequences, 16 potential N-linked glycosylation sites, and conserved cysteine residues. Immunoblot analysis detected three protein forms (150 kDa, 90-110 kDa, and 55 kDa) representing full-length and proteolytically cleaved gB products. Using sera from naturally RhCMV-infected rhesus monkeys, the researchers found that gB is immunogenic, with nearly 100% seropositivity. Importantly, several HCMV gB-specific monoclonal antibodies cross-reacted with RhCMV gB, and some could neutralize RhCMV infection. The antigenic domain 1 (AD-1) region of RhCMV gB proved immunodominant during natural infection. These findings suggest that RhCMV could serve as a useful animal model for studying cytomegalovirus pathogenesis and immune responses.
Key findings
- RhCMV gB shares 60% amino acid identity and 75% similarity with HCMV gB, with conserved structural features including cysteine residues and N-linked glycosylation sites
- RhCMV gB undergoes similar proteolytic processing to HCMV gB, producing full-length (150 kDa) and cleaved products (55 kDa and 90-110 kDa)
- Nearly 100% of naturally infected rhesus monkeys developed antibodies against RhCMV gB, with AD-1 being the immunodominant antigenic region
- Cross-reactive HCMV gB-specific monoclonal antibodies recognized RhCMV gB, and the human monoclonal antibody 89-104 could neutralize RhCMV infection
- RhCMV represents a potentially useful primate model for investigating cytomegalovirus pathogenesis and immune surveillance
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Abstract
The nucleotide sequence of the gene encoding glycoprotein B (gB) of rhesus cytomegalovirus (RhCMV) was determined and the protein characterized. The open reading frame of gB encoded a protein of 854 amino acids with 60% identity and 75% similarity at the amino acid level to human cytomegalovirus (HCMV) gB. Cysteine residues in the extraluminal part of the protein are perfectly conserved. Out of the 16 potential N-linked glycosylation sites present in HCMV gB, 15 are conserved in RhCMV gB. Immunoblot analyses with antisera detected three bands of 150 kDa, 90-110 kDa and 55 kDa representing the full-length gB as well as the proteolytic cleavage products. Cross-reactivity and cross-neutralization of a number of HCMV gB-specific monoclonal antibodies with RhCMV gB indicated sharing of immunogenic epitopes between the two molecules. The RhCMV gB regions corresponding to antigenic domains AD-1, 2 and 3 of HCMV gB were immunogenic during natural RhCMV infection with the AD-1 region being the immunodominant domain. The data indicate that RhCMV might represent a useful model to investigate pathogenesis and immune surveillance of cytomegaloviruses.