TABLE 3.
V3 peptide effects on serum neutralization ID50 titers against the clade B V3 neutralization-sensitive isolate JRFL-Δ301a
| Serum | Mock peptide ID50 | Scrambled V3 peptide
|
% Neut. to scrambled peptidec | BaL V3 peptide
|
% Neut. to V3 peptidee | Net % neut. to V3f | ||
|---|---|---|---|---|---|---|---|---|
| ID50 | ID50 fold decreaseb | ID50 | ID50 fold decreased | |||||
| Strong/broadly neutralizing sera | ||||||||
| 1 | 5,704 | 10,019 | 0.6 | 0 | 3,657 | 1.6 | 38 | 38 |
| 18 | 901 | 807 | 1.1 | 9 | 1,167 | 0.8 | 0 | 0 |
| 20 | 507 | 421 | 1.2 | 17 | 291 | 1.7 | 41 | 25 |
| 30 | 786 | 833 | 0.9 | 0 | 615 | 1.3 | 23 | 23 |
| 45 | 3,291 | 3,631 | 0.9 | 0 | 2,445 | 1.3 | 23 | 23 |
| Weak/limited neutralizing sera | ||||||||
| 6 | 465 | 502 | 0.9 | 0 | 126 | 3.7 | 73 | 73 |
| 8 | 531 | 553 | 1 | 0 | 162 | 3.3 | 70 | 70 |
| 15 | 89 | 91 | 1 | 0 | 2.5 | 35.6 | 97 | 97 |
| 19 | 204 | 277 | 0.7 | 0 | 28 | 7.3 | 86 | 86 |
| 29 | 1,889 | 1,126 | 1.7 | 41 | 443 | 4.3 | 77 | 36 |
| 31 | 80 | 60 | 1.3 | 23 | 2.5 | 32 | 97 | 74 |
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.
Serum ID50 value ratio in the absence and presence of scrambled V3 peptide, calculated as (ID50 with mock peptide/ID50 with scrambled V3 peptide).
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.
Serum ID50 value ratio in the absence and presence of V3 peptide, calculated as ID50 with mock peptide/ID50 with V3 peptide.
Indicator of percentage of ID50 change by the presence of V3 peptide, calculated as [1 − (ID50 with mock peptide/ID50 with V3 peptide)] × 100.
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.