Species specificity of macaque rhadinovirus glycoprotein B sequences

Abstract

All members of the Herpesviridae family contain sequences for a highly conserved glycoprotein B (gB) gene. We investigated the phylogenetic relationships of gB sequences from eight independent rhadinovirus isolates obtained from three species: rhesus (Macaca mulatta), cynomologus (Macaca fasicularis), and pig-tailed (Macaca nemestrina) macaques. Samples were derived from monkeys housed at four separate facilities. Analysis of these eight independent gB sequences revealed five regions of heterogeneity within the 823- to 829-amino-acid polypeptides: residues 1 to 65, 120 to 185, 255 to 300, 352 to 393, and 412 to 457. The remaining regions of gB were highly conserved among the different macaque isolates. Overall divergence among these gene sequences ranged from 0.1 to 7.2% at the amino acid level. Phylogenetic trees constructed with our macaque rhadinovirus gB sequences and those derived from additional subfamilies or genera (alpha, beta, gamma-1, and gamma-2) revealed that the macaque gB sequences branched with other gamma-2 herpesvirus gB sequences and that within the gamma-2 genera, the macaque gB sequences clustered as a distinct branch. The eight macaque rhadinovirus gB sequences were all approximately equidistant from Kaposi sarcoma-associated herpesvirus (KSHV) gB sequences and had a shorter evolutionary distance to KSHV gB sequences than to any other herpesvirus, including the gamma-2 herpesvirus saimiri (HVS) of New World squirrel monkeys. The macaque gB sequences did not cluster according to the facility of origin, but did cluster according to the species of origin, displaying less intraspecies divergence (0.1 to 2.9%) than interspecies divergence (3.3 to 7.2%). These results demonstrate a close relatedness of rhadinovirus isolates from different macaque species.

FIG. 1

Alignment of gB amino acid sequences. An alignment was constructed with the full-length gB amino acid sequences from nine macaque rhadinovirus isolates, including RRV (Macaca mulatta), CRV (Macaca fasicularis), and PMRV (Macaca nemestrina); one KSHV isolate (accession no. AAC57085); and two partial sequences from retroperitoneal fibromatosis tissues from Macaca mulatta (RFHMm, accession no. AAC72187) and Macaca nemestrina (RFHMn, accession no. AAC72188). RRV26-95 and RRV17577 gB sequences were obtained from GenBank (accession no. AAC58686 and AAD21335, respectively). ClustalW software was used to determine alignments of the gB sequences. The gB sequences were compared to the RRV26-95 sequence (8) (shown on the top line). Deletion polymorphisms between sequences are indicated by dashes (−). Conserved cysteine residues and conserved potential N-linked glycosylation sites (N-X-S or N-X-T) are highlighted in black. The five variable regions (residues 1 to 65, 120 to 185, 255 to 300, 352 to 393, and 412 to 457) are highlighted in gray.

FIG. 1

Alignment of gB amino acid sequences. An alignment was constructed with the full-length gB amino acid sequences from nine macaque rhadinovirus isolates, including RRV (Macaca mulatta), CRV (Macaca fasicularis), and PMRV (Macaca nemestrina); one KSHV isolate (accession no. AAC57085); and two partial sequences from retroperitoneal fibromatosis tissues from Macaca mulatta (RFHMm, accession no. AAC72187) and Macaca nemestrina (RFHMn, accession no. AAC72188). RRV26-95 and RRV17577 gB sequences were obtained from GenBank (accession no. AAC58686 and AAD21335, respectively). ClustalW software was used to determine alignments of the gB sequences. The gB sequences were compared to the RRV26-95 sequence (8) (shown on the top line). Deletion polymorphisms between sequences are indicated by dashes (−). Conserved cysteine residues and conserved potential N-linked glycosylation sites (N-X-S or N-X-T) are highlighted in black. The five variable regions (residues 1 to 65, 120 to 185, 255 to 300, 352 to 393, and 412 to 457) are highlighted in gray.

FIG. 2

Phylogenetic analysis of gB genes from nine macaque rhadinovirus isolates and KSHV. N, NEPRC; C, CPRC; O, ORPRC; W, WRPRC. ClustalW software was used to align gB amino acid sequences. The neighbor-joining method was used to generate this phylogeny by using PAUP* software (26), with KSHV sequences serving as the outgroup. Bootstrap values from 1,000 replications (repeated three times) are shown for each branch point.

FIG. 3

Phylogenetic analysis of gB gene sequences from macaque rhadinoviruses and representative alpha, beta, gamma-1, and gamma-2 herpesviruses. The alignment was created by using ClustalW software. The neighbor-joining method was used to generate this phylogeny by using PAUP* software (26) with alpha and beta herpesvirus gB sequences serving as the outgroup. Bootstrap values from 1,000 replications (repeated three times) are shown for each branch point. Branch lengths are drawn in proportion to distances. Sequences not determined in this study were acquired from GenBank. Accession numbers are as follows: KSHV, AAC57085; MHV68, AAB06229; HVS, P24905; Equine herpesvirus 2, (EHV2); AAC13795; EBV, P02188; Human simplex virus 1 (HSV1), P10211; Varicella-zoster virus (VZV), P09257; Human cytomegalovirus (HCMV), AAA45928; and Human herpesvirus 6 (HHV6), P36319.