Phylogenetic analysis of HERV-K LTR-like elements in primates: presence insome New World monkeys and evidence of recent parallel evolution in these species and in Homo sapiens

Solitary long terminal repeats (LTRs) of the human endogenous retroviruses K family (HERV-K) have been found to be coexpressed with sequences of close ly located genes. We identified forty-three HERV-K LTR-like elements in pri mates (African great apes, two Old World monkeys, and two New World monkeys ) and analyzed them along with human-specific HERV-K LTRs. We report detect ion of HERV-K LTR-like elements from New World monkeys, as represented by t he squirrel monkey and the night monkey, for the first time. Analysis revea led a high degree of sequence homology with human-specific HERV-K LTRs. A p hylogenetic tree obtained by the neighbor-joining method revealed that five sequence (SMS-1, 2, 5, 6, 7) from the squirrel monkey and three sequences (NM6-4, 5, 9) from the night monkey are more closely related to human-speci fic HERV-K LTRs than they are to those of apes (the chimpanzee and gorilla) and Old World monkeys (the African green monkey and rhesus monkey). The fi ndings are consistent with the concept the HERV-K LTR-like elements have pr oliferated independently and recently in the genome of primates, and that s uch proliferation has been more recent in Homo sapiens and in these represe ntatives of New World monkeys than in some Old World monkeys.