Fig. 1
From: Diversity of endogenous avian leukosis virus subgroup E (ALVE) insertions in indigenous chickens
The diverse impacts of endogenous retroviruses. Intact endogenous retroviruses (ERV) share a conserved archetypal structure of retroviral proteins (gag, pol and env) enclosed by two long terminal repeats (LTR) which are identical at the point of integration in the host genome. ERV integration site largely determines its immediate impact on the host, as integration within or near genes may modulate host gene expression and facilitate continued ERV expression of retroviral gene products or intact virions, which can elicit persistent physiological stress on the host. As ERV copy number increases in the genome, ERV recombination facilitates intra- and interchromosomal rearrangements and acts as recipient sequence for recombination with related exogenous retroviruses (XRV)