What are endogenous retroviruses and why are they dangerous?
A retrovirus is a RNA virus that is reverse-transcribed into complementary DNA (cDNA) and integrated into the host cell genome to replicate and complete its life-cycle. Endogenous retroviruses (ERVs) are elements in the genomes of all higher organisms including human beings, which are very similar to the genomes of retroviruses. They are flanked by long terminal repeats (LTRs) and carry genes coding for structural and coat proteins of the virus as well as the reverse transcriptase and integrase enzymes (required for reverse-transcription and integration of the viral genome into the host genome) [14]. There are two theories on how ERVs may have evolved. Howard Temin, Nobel laureate who co-discovered the enzyme reverse transcriptase, suggested that they have evolved from retro-transposons — mobile genetic elements with reverse transcriptase — which are part of the genomes of all higher organisms. Alternatively, ERVs may have evolved from exogenous viruses, foreign viruses that have bec
