ERVW-1 and infection: where GL8 WT infection of MCC-CRD1 was 300-fold less efficient, whereas infection with the T271I and Δ2N mutants was reduced by only 27 and 47-fold respectively, suggesting that the presence of the T271I mutation, but not the N342Y mutation, facilitated the interaction between the GL8 Env and CRD1 of CD134.