Molecular evolution of the HERV-E family in primates

More than 50 copies of HERV-E family elements have been estimated to exist in the human genome. Here we examined the recent evolutionary history of the HERV-E family by a PCR approach using genomic DNA from hominoid primates and a human monochromosomal panel. From the HERV-E family, 25 and 68 env fragments, were identified and analyzed from hominoid primates and human chromosomes 1, 2, 3, 4, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 19, X, and Y, respectively. They showed 76.7-99.6% sequence similarity to that of HERV-E (accession no. M10976). Phylogenetic analysis of HERV-E env family distinctively divided into two groups (groups I and II) that each contained three subgroups. Divergence times of the two groups were estimated as 10.7 MYr for group I and 41.3 MYr for group II using an average evolutionary rate of 0.3% per MYr. These data are consistent with that of PCR analysis, which showed a band of the HERV-E family in the genomes of the hominoids, Old World monkeys, and New World monkeys. Therefore, the HERV-E family may have integrated into the primate genome after prosimians and New World monkeys diverged. Then they proliferated extensively in the genome of humans and great apes during primate evolution.