John R, Arango-Jaramillo S, Schwartz DH; International Conference on AIDS.

Int Conf AIDS. 2002 Jul 7-12; 14: abstract no. MoPeA3079.

Dept. of Molec. Microbiol. &Immunol., Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States

BACKGROUND: Our in vitro challenge assay (IVCA) reveals resistance to exogenous R5 and X4 HIV in PBMCs from HIV+ aviremic donors, and, to lesser degrees, exposed uninfected donors (R5 only), and canarypox-HIV vaccinees. Qualitative (+/-) scoring of IVCA cultures was most useful for comparing resistance between groups of donors. We have now modified IVCA for quantitation of individual donor samples, greatly enhancing its utility for vaccine assessment. METHODS: Activated 8-well PBMC cultures challenged with 3, 10, & 30 TCID50 R5 HIV-1 BaL were sampled at challenge days 0, 7, & 10, and assayed for p24 using a wide dynamic range (20-20,000 pg/ml) EIA. RESULTS: All day 10 replicates from 18 controls were (+) after challenge with 30 TCID50 (means from 15 - 109 ng/ml). At 10 & 3 TCID50, 94% & 64% of wells were (+), respectively. At day 7, 100, 87, & 55 % of wells were (+) at 30, 10, & 3 TCID50, respectively. For each PBMC sample, mean p24 increased by ~ 0.5 log from day 7 to 10. On both days, for each sample, lower challenge doses gave fewer (+) wells and/or lower mean p24 values. While PBMC susceptibility varied by donor, any PBMC sample always revealed significant differences in mean p24 between at least two doses, or days 7 vs. 10. We modeled vaccine induced resistance by adding either suboptimal [beta]-chemokines or non-neutralizing cytophilic anti-HIV Abs to normal susceptible PBMCs. In both models, IVCA detected significantly increased resistance in 3 / 4 samples at one or more challenge doses. CONCLUSIONS: IVCA quantitatively detects modest (3-fold) changes in resistance to HIV, expressed as mean p24 and fraction (+) wells. The format also allows for interpretation of data in terms of 3-10 fold differences in challenge dose susceptibility, or days required (7 vs. 10) to reach comparable p24 production. The assay is sensitive to chemokine and Ab dependent (as well as CTL dependent) protective mechanisms.

Publication Types:

• Meeting Abstracts

Keywords:

• AIDS Vaccines
• Acquired Immunodeficiency Syndrome
• Chemokines
• Chemokines, CC
• Evaluation Studies
• HIV Infections
• HIV Seropositivity
• HIV-1
• In Vitro
• T-Lymphocytes, Cytotoxic
• methods

Other ID:

• GWAIDS0013438

UI: 102250936

From Meeting Abstracts