Evidence that reverse transcriptase is a component of murine epididymal fluid.

The sperm-free fluid fraction of epididymal semen obtained from males of four mouse strains contained a DNA polymerase activity with properties of murine retrovirus reverse transcriptase (RT). Epididymal fluids from two of the strains of mice, NIH Swiss and New Zealand Black (NZB), had an order of magnitude more enzyme activity per microgram of protein than did the fluids of C57Bl/6 and Balb/c males. Most of the enzyme activity in the Swiss and NZB males, but not in the C57Bl/6 and Balb/c males, banded in isopycnic sucrose gradients at the buoyant density of retrovirus particles. The males were fertile and free of tumor or other detectable disease up to 17 months of age. The evidence suggests RT activity is ubiquitous in the male reproductive tract of mice and may or may not be associated with virus particles.