The LCMV L260F mutation significantly reduces its affinity for α-DG. (A) GP1 of LCMV WE54 was mutated at amino acid position 260 to produce a low affinity α-DG binding envelope (LCMV L260F) similar to the wild-type envelope of LCMV Arm53b. Leucine at position 260 results in high affinity binding to α-DG; phenylalanine reduces its affinity. (B) LCMV pseudotypes and wild type virus were compared for their affinity to immobilized α-DG in an ELISA-based assay detecting bound virions. (C) Increasing amounts of soluble α-DG were preincubated with FIV-WE54 (filled squares) or FIV-L260F (filled circles) to neutralize transduction measured by counting positive cells per well. BSA preincubation was used as a control (open symbols). Wild-type LCMVs with known high (WE54) or low (WE2.2) affinity for α-DG were used as controls for contrast with pseudovirions and depicted in (B, right panel) and (D). n = 3. Standard deviations are plotted.