SHOT THROUGH. “Post-insertional recombinations, deletions, and mutations have rendered all known human endogenous retroviruses (HERVs) non-infectious. However some, particularly the most recently acquired proviruses of the HERV-K(HML-2) family, can expresses viral proteins and produce viral particles.”
http://journal.frontiersin.org/article/10.3389/fonc.2013.00246/full