Explaining Endogenous Retroviruses

What are endogenous retroviruses —backwards viruses from within?

Endogenous retroviruses originate from retroviruses, which are a distinctive family of viruses that infect vertebrates. During infection, retroviruses enter host cells, and convert their RNA genomes to DNA by reverse transcription. This is in direct opposition to the central dogma of molecular biology, which states that the flow of genetic information passes from DNA to RNA, hence the name retrovirus. After reverse transcription, the DNA copy of the viral genome is integrated into the host genome, enabling expression of viral genes via the host cellular machinery to produce more viruses. Occasionally, integration occurs in a germline cell (those that produce sperm or eggs), allowing the retroviral insertion to be inherited by host progeny as an endogenous retrovirus or ‘ERV’ for short. The term endogenous is applied since ERVs are inherited in a similar manner to genes, residing within the host genome in every nucleated cell of the organism.

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