Scattered among human and animal genomes are a class of repetitive genetic elements called endogenous retroviruses (ERVs), which are generally considered remnants of ancient viral infections. Because humans and chimpanzees share ERVs at similar genomic positions, evolutionists use these elements as another argument for common ancestry. From a creationist perspective, ERVs may have been created in strategic locations of the genome to perform essential functions, such as synchronized regulation of interspersed genetic elements. Since some human endogenous retroviruses (HERVs) contain putative steroid hormone-response elements, it would be reasonable that expression of such HERVs would be controlled by sex hormones, and might even demonstrate temporal patterns during the female menstrual cycle. Accordingly, we quantified the transcription dynamics of multiple HERV elements in peripheral blood leukocytes using SYBR Green-based RT-PCR in male and female human subjects. Preliminary data indicated that expression of HERVs indeed followed a temporal pattern in females. Moreover, transcription activity of ERV genes was strongly correlated with blood levels of progesterone. The same pattern was demonstrated for HERV-K elements and the syncytin-1 gene encoded by ERVWE1. These results suggest coordinated regulation of some ERV elements by progesterone in the female.
