TABLE 4.

Characterization of A12/D7 mutants

Mutations in residues 101 and 102 were carried out on the parental A12 and D7 VHH. All the mutants were able to bind to IIIB gp120 in ELISA and neutralized HIV-1 IIIB with high potency. Mutants 1 and 2 lost the ability to neutralize both C222 and 92BR025 with just a point mutation change in residue 101. Mutant 5 retained the ability to neutralize both C222 and 92BR025 despite a D102E mutation. Mutants 6 and 8 are double back mutations where the YYD¹⁰² and YNY¹⁰² motifs were inter-switched, which resulted in a corresponding change in the neutralization phenotype. Residues 101 and 102 at the end of the CDR3 loop are therefore important for the subtype C Env specificity tested here.