ERVW-1 and infection: Although we cannot exclude the possibility that different fragments (pol or env) may be amplified from distinct HIV-1 strains in an individual patient, this probability should be very rare since any infection with dual or multiple HIV-1 quasi-species will result in an outgrowth of dominant/major HIV-1 strain during primary infection, which may be a new recombinant strain formed quickly after dual or multiple infections [29].