Molecular systematics: data mining of canine endogenous retroviruses, CFERV

Sammanfattning: Endogenous retroviruses (ERVs) were discovered in the 1960s and in their complete form they consist of two LTRs (long terminal repeat sequences) that are each located on either side of the chain/element. ERVs contain the following genes: gag, pro, pol and env .Ccomplete ERVs are 8-10 kb long and have their best fitness in the enzyme that use reverse transciptase polymerase from single stranded RNA as template to produce DNA and in the possibility the host is not damaged lethally and no selection against the ERV element come into force. When a retrovirus infects a germ cell, the retrovirus inserts its genome into the infected cell and become a part of the entire genome. These ERVs are inherited according to Mendelian expectations in the same way as all other genes in the genome. The phenomenon of ERV inheritance is called vertical contagion. The first exogenous retroviruses that infected a germ cell and became endogenous could have appeared at any time over an extended evolutionary time-scale between 2 to 70 million years ago. Even a horisontal contagion is possible, from one species to another through exogenous retrovirus infection. A possible way of horisontal contagion is when animals of different species are forced to live in a limited area. On average it has been estimated that it takes one million year until retroviral integration is fixed within a population. All veterbrates have endogenous retroviruses in their genomes, the ERV elements are mostly old, truncated and non-functional. Still some of them have open reading frames in RV gene are low in LTR divergence and in frequency of nonsense mutation causing premature stop of translation and frame shift mutations. The canine genome has been effective in protection from extensive retroviruses integration, the amount in dog is expected to be a fifth of the real ERV amount in species like human and chimpanzees.