Search

The development of a rapid and efficient system to identify human immunodeficiency virus type 1 (HIV-1)-infected individuals with broad and potent HIV-1-specific neutralizing antibody responses is an important step toward the discovery of critical neutralization targets for rational AIDS vaccine design. In this study, samples from HIV-1-infected volunteers from diverse epidemiological regions were screened for neutralization responses using pseudovirus panels composed of clades A, B, C, and D and circulating recombinant forms (CRFs). Initially, 463 serum and plasma samples from Australia, Rwanda, Uganda, the United Kingdom, and Zambia were screened to explore neutralization patterns and selection ranking algorithms. Samples were identified that neutralized representative isolates from at least four clade/CRF groups with titers above prespecified thresholds and ranked based on a weighted average of their log-transformed neutralization titers. Linear regression methods selected a five-pseudovirus subset, representing clades A, B, and C and one CRF01_AE, that could identify top-ranking samples with 50% inhibitory concentration (IC50) neutralization titers of ≥100 to multiple isolates within at least four clade groups. This reduced panel was then used to screen 1,234 new samples from the Ivory Coast, Kenya, South Africa, Thailand, and the United States, and 1% were identified as elite neutralizers. Elite activity is defined as the ability to neutralize, on average, more than one pseudovirus at an IC50titer of 300 within a clade group and across at least four clade groups. These elite neutralizers provide promising starting material for the isolation of broadly neutralizing monoclonal antibodies to assist in HIV-1 vaccine design.

There is an urgent need for low-cost human immunodeficiency virus type 1 (HIV-1) viral load (VL) monitoring technologies in resource-limited settings. An automated TaqMan real-time reverse transcription-PCR (RT-PCR) assay was transferred to the laboratory of the Centre de Diagnostic et de Recherches sur le SIDA, Abidjan, Côte d'Ivoire, and assessed for HIV-1 RNA VL testing in 806 plasma samples collected within four ANRS research programs. The detection threshold and reproducibility of the assay were first determined. The quantitative results obtained with this assay were compared with two commercial HIV-1 RNA kits (the Versant version 3.0 and Monitor version 1.5 assays) in specimens harboring mainly the circulating recombinant form 02 strain (CRF02). The clinical evaluation of this test was done in different situations including the early diagnosis of pediatric infection and the monitoring of antiretroviral-treated patients. The quantification limit of our method was 300 copies/ml. The HIV-1 RNA values obtained by real-time PCR assay were highly correlated with those obtained by the Versant kit (r= 0.901;P< 0.001) and the Monitor test (r= 0.856;P< 0.001) and homogeneously distributed according to HIV-1 genotypes. For the early diagnosis of pediatric HIV-1 infection, the sensitivity and specificity of the real-time PCR assay were both 100% (95% confidence intervals of 93.7 to 100.0 and 98.3 to 100.0, respectively), compared to the Versant results. Following initiation of antiretroviral treatment, the kinetics of HIV-1 RNA levels were very comparable, with a similar proportion of adults and children below the detection limit during follow-up with our technique and the Versant assay. The TaqMan real-time PCR ($12 per test) is now routinely used to monitor HIV-1 infection in our laboratory. This technology should be further evaluated in limited-resource countries where strains other than CRF02 are prevalent.