Molecular phylogeny of endogenous retrovirus HERV-F family in Japanese and rhesus monkeys

A new human endogenous retroviral family (HERV-F) has recently been identified from the human chromosome 7q31.1-q31.3 that was identical to the XA34 cDNA clone isolated from a human glioma cDNA library with an ERV-9 probe. The current study investigated pol fragments of the HERV-F family from Japanese and rhesus; monkeys and compared them with those of the HERV-F (Hu-XA34) family. Fourteen pol fragments of the HERV-F family were detected from the monkeys, which showed a 78.7-95.4% sequence similarity with those of HERV-F (Hu-XA34). Clones FJM-1, FJM-7, FJM-14, and FJM-15 from the Japanese monkey and FRH-1 and FRH4 from the rhesus monkey exhibited no disruption due to point mutation or insertions/deletions. The ratio of synonymous to non-synonymous substitutions indicated that negative selective pressure was acting on these clones. Therefore, the pol gene sequences could be associated with an active provirus in the monkey genomes. A phylogenetic analysis of the pol fragments from humans and monkeys using the neighbor-joining and maximum parsimony methods showed six groups, indicating that either the HERV-F family was amplified at least six times after its original integration into the monkey genome or the occurrence of independent integration events during primate evolution.