Retrovirus Genes Make Up 5 - 8% of Human Genome
Lucas Meadows stashed this in Genetics
I find this fascinating. I guess certain types of viruses (endogenous retroviruses -- whatever that means) can occasionally infect germ cells, which produce gametes, and transfer their own genetic material not only into the host, but also the host's future offspring.
Genetic code from retroviruses has been found to compose some 8 percent of the human genome, having been copied in during replication and left to be inherited by us and our progeny. But non-retroviral RNA viruses do not use their host's DNA to replicate—and some do not even enter the host cell's nucleus. Nevertheless, new research has turned up surprising evidence that some of these viruses are enmeshed in the genomes of vertebrates—including humans and other mammals.
Wikipedia says that "thousands of endogenous retroviruses exist in human DNA" and that this may be involved in certain autoimmune disorders.
Evolutionary history of HERVs (human endogenous retroviruses) in primates:
HERVs are remnants of ancient germ line infections with exogenous retroviruses that have been genetically fixed and vertically transmitted since millions of years. During the course of evolution they have been amplified and spread throughout the genome by retrotransposition and/or reinfection.