Patterns of electrostatic charge across the V3 region are depicted (positive charges in blue, negative charges in red). Gains in positive charge at positions 11 and 25 are highlighted by * and ^, respectively. The V3 amino acid sequences are provided below each modeled structure, and basic amino acids are highlighted in blue. Subject 2 (G11 vs. 11R), subject 3 (S11 vs. 11R), subject 7 (E25 vs. 25K) and subject 9 (E25 vs. 25R).