TABLE 3.

V3 peptide effects on serum neutralization ID50 titers against the clade B V3 neutralization-sensitive isolate JRFL-Δ301a

SerumMock peptide ID50Scrambled V3 peptide% Neut. to scrambled peptidecBaL V3 peptide% Neut. to V3 peptideeNet % neut. to V3f
ID50ID50 fold decreasebID50ID50 fold decreased
Strong/broadly neutralizing sera
    15,70410,0190.603,6571.63838
    189018071.191,1670.800
    205074211.2172911.74125
    307868330.906151.32323
    453,2913,6310.902,4451.32323
Weak/limited neutralizing sera
    64655020.901263.77373
    8531553101623.37070
    158991102.535.69797
    192042770.70287.38686
    291,8891,1261.7414434.37736
    3180601.3232.5329774
  • a The assay was validated against a set of V3-directed antibodies (2182, 2191, 2219, 2442, 2456, 447-52D, and 1.3D) (22), and complete inhibition of antibody-mediated neutralization against the BaL.01, 6535, and SF162 isolates was demonstrated by the BaL.01 V3-derived peptide, while the V3 scrambled peptide had no effect on neutralization. Neither peptide demonstrated any impact on 2G12- or 2F5-mediated neutralization of the BaL.01, 6535, or SF162 pseudotyped virus. The final concentration of the V3 peptides in the presence of serum and virus was 25μg/ml.

  • b Serum ID50 value ratio in the absence and presence of scrambled V3 peptide, calculated as (ID50 with mock peptide/ID50 with scrambled V3 peptide).

  • c Indicator of percentage of ID50 change by the presence of scrambled V3 peptide, calculated as [1 − (ID50 with mock peptide/ID50 with scrambled V3 peptide)] × 100.

  • d Serum ID50 value ratio in the absence and presence of V3 peptide, calculated as ID50 with mock peptide/ID50 with V3 peptide.

  • e Indicator of percentage of ID50 change by the presence of V3 peptide, calculated as [1 − (ID50 with mock peptide/ID50 with V3 peptide)] × 100.

  • f Indicator of percentage of neutralization directed against the V3 epitope, calculated as the percentage of ID50 change by the presence of V3 peptide − percentage of ID50 change by the presence of scrambled V3 peptide. Values greater than 50% are shown in boldface type.