ERVW-1 and infection: In contrast to K11, which binds to a glycan hole on the gp120 surface of the SIV Env trimer and completely neutralizes SIVmac239 K180S at high multiplicities of infection [37], residual infectivity became detectable at a 10-fold virus dilution (1.4 ng/ml p27) in the presence of PGT145 (S2 Fig).