The finding of this new gibbon virus, which clusters with a related chimpanzee virus in the rhadinovirus 2 genogroup, suggests the existence of a novel [gamma]-2-herpesvirus in humans.
Among the latter, recent comparison and phylogenetic analyses of all available sequences support the existence of two distinct genogroups called RV1 and RV2 for Rhadinovirus genogroups 1 and 2 (5-9).
These are PanRHV1a/PtRV1 (Pan rhadinovirus 1a/Pan troglodytes rhadinovirus 1), PanRHV 1b (Pan rhadinovirus 1b) and GorRHV1 (gorilla rhadinovirus 1) from chimpanzees and gorillas respectively, in the RV1 group and PanRHV2 (Pan rhadinovirus 2) from chimpanzees in the RV2 group (7,10,11).
leucogenys (gibbon 7), database searches, using BLAST web server (available from http://www.ncbi.nlm.nih.gov/blast/Blast.cgi), indicated a novel [gamma]-herpesviral DNA polymerase sequence that was closely related to the Rhadinovirus genus strains.
Nucleotide comparison of a 451-bp fragment, corresponding to the best alignment of all the [gamma]-herpesviruses available sequences, indicated that the novel gibbon rhadinovirus sequence was more closely related to the corresponding sequences of the RV2 genogroup viruses (76%, 73%, and 71% of nucleotide identity with ChRV2 (Chlorocebus rhadinovirus 2), MndRHV2 (Mandrillus rhadinovirus 2) and PanRHV2, respectively), than to the corresponding sequences of the RV1 genogroup viruses (70%, 69%, and 63% of nucleotide identity with KSHV, PanRHV1a, and PanRHV1b fragments, respectively).
However, all analyses clearly localized, with bootstrap values from 83% to 85%, the novel gibbon viral sequence (HyloRHV2) within the Rhadinovirus genus in the RV2 genogroup (Figures 1 and 2; data not shown).
In conclusion, our data demonstrated for the first time the existence of a gibbon rhadinovirus. Furthermore, after the recent demonstration of two distinct Rhadinovirus lineages within the common chimpanzees (7), and based on the known molecular evolution of herpesviruses, our findings of a novel RV2 virus in gibbon may suggest the possible existence of a novel [gamma]-2-herpesvirus in humans, belonging to the RV2 genogroup.