ERVW-1 and infection: A single amino acid change from the major T/F virus (Arg189Ser), likely derived from the minor T/F virus was observed in 90% of the V2 sequences analyzed at week 21 post-infection (the “Ser” is more likely derived from the minor T/F through recombination, than a de novo substitution based on the env sequences at week 21 that appear to be very closely related to the minor T/F) (Figure S1b).