FIG 11.

Schematic representation of the proposed model for the evolution of ERV-DC7 env (Refrex-1). The origin of ERV-DC7 was generated by the integration of an ancestral retrovirus. Postinsertional mutations were accumulated in this origin, and several alleles arose from it as intermediates. Some were inactivated by the mutations that suppressed Env functions, such as premature or latent stop codons, G407R, and N427I-A429T. Present alleles were generated by multiple recombination events among these intermediate alleles. The premature stop codon may have been distributed and fixed within the population of domestic cats through these processes.