Evaluation Summary:
This work is a bioinformatic analysis of HML-2-like proviruses found in the genomes of Rhesus Macaques, which convincingly argues that an HML-2 provirus underwent an ancient recombination event with a HERV-K (HML-8) related virus. The authors also provide data to suggest that the recombinant retrovirus may have acquired a distinct mechanism for the regulation of expression of spliced and unspliced transcripts. This paper should be of broad interest to virologists as it uses molecular 'fossil-like' evidence contained in the genomes of modern pirates to document the generation of what could be considered a previously undescribed retrovirus species, through recombination.
(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 and Reviewer #2 agreed to share their name with the authors.)