Comparative analyses of LTRs of the ERV-H family of primate-specific retrovirus-like elements isolated from marmoset, African green monkey, and man

We have isolated 8 different long terminal repeat (LTR) sequences of the ERV-H family of endogenous retrovirus-like elements from human chromosome 18, 9 from African green monkey, and 28 from marmoset. Human ERV-H LTRs have been divided into three types designated Type I, Type la, and Type II. Comparative analyses of the 45 isolated LTRs and 60 human ERV-H LTRs enabled a further subdivision into 13 subtypes. Type I elements were widely distributed in all three species. Their average evolutionary age (40 MYr), estimated by a consensus sequence approach, suggests that they first expanded in the genomes at the time New- and Old World monkeys diverged. The occurence of some very old Type I sequences indicate that ERV-H elements may have integrated even before prosimians and primates diverged. Type la and II elements were found in both monkey species. Promoter active Type I and Type la LTRs were found while Type II LTRs were inactive. Promoter active Type I LTRs generally contained a functional GC/GT box immediately 3' to the TATA box, providing strong binding of Spl family proteins, while the highly promoter active Type la element H6 contained synergistically acting Spl binding sites located in the us enhancer region. (C) 1997 Academic Press.