Comparison of capillary based microflurometric assay for CD4+ T cell count estimation with dual platform Flow cytometry.

The CD4+ T cell count estimation is an important monitoring tool for HIV disease progression and efficacy of anti-retroviral treatment (ART). Due to availability of ART at low cost in developing countries, quest for reliable cost effective alternative methods for CD4+ T cell count estimation has gained importance. A simple capillary-based microflurometric assay (EasyCD4 System, Guava Technology) was compared with the conventional flow cytometric assay for estimation of CD4+ T cell counts in 79 HIV infected individuals. CD4+ T cell count estimation by both the assays showed strong correlation (r = 0.938, p < 0.001, 95% CI 0.90 to 0.96). The Bland Altman plot analysis showed that the limits of variation were within agreeable limits of +/- 2SD (-161 to 129 cells/mm3). The Easy CD4 assay showed 100% sensitivity for estimating the CD4+ T cell counts < 200 cells/mm3 and < 350 cells/mm3 and 97% sensitivity to estimate CD4+ T cell count < 500 cells/mm3. The specificity ranged from 82 to 100%. The Kappa factor ranged from 0.735 for the CD4+ T cell counts < 350 cells/mm3 to 0.771 for < 500 cells/mm3 CD4+ T cell counts. The system works with a simple protocol, is easy to maintain and has low running cost. The system is compact and generates minimum amount of waste. Hence the EasyCD4 System could be applied for estimation of CD4+ T cell counts in resource poor settings.

Cytolytic T lymphocytes (CTLs) from HIV-1 subtype C-infected Indian patients recognize CTL epitopes from a conserved immunodominant region of HIV-1 Gag and Nef.

Analysis of the human immunodeficiency virus type 1 (HIV-1) cytolytic T lymphocyte (CTL) epitopes recognized by the targeted population is critical for HIV-1 vaccine design. Peripheral blood mononuclear cells from 47 Indian subjects at different stages of HIV-1 infection were tested for HIV-1 Gag-, Nef-, and Env-specific T cell responses by interferon (IFN)- gamma enzyme-linked immunospot (ELISPOT) assay, using pools of overlapping peptides. The Gag and Nef antigens were targeted by 83% and 36% of responders. Five immunodominant regions, 4 in Gag and 1 in Nef, were identified in the study; these regions are conserved across clades, including the African subtype C clade. Three antigenic regions were also found to be recognized by CTLs of the study participants. These regions were not identified as immunodominant regions in studies performed in Africa, which highlights the importance of differential clustering of responses within HIV-1 subtype C. Twenty-six putative epitopes--15 Gag (10 in p24 and 5 in p17), 10 Nef, and 1 Env (gp 41)--were predicted using a combination of peptide matrix ELISPOT assay and CTL epitope-prediction software. Ninety percent of the predicted epitopes were clustered in the conserved immunodominant regions of the Gag and Nef antigens. Of 26 predicted epitopes, 8 were promiscuous, 3 of which were highly conserved across clades. Three Gag and 4 Nef epitopes were novel. The identification of conserved epitopes will be important in the planning of an HIV-1 vaccine strategy for subtype C-affected regions.

Rapid disease progression in human immunodeficiency virus type 1-infected seroconverters in India.

To determine if the early immunological and virological events of HIV infection are unique in a setting with limited access to health care and HIV-1 subtype C infection, we undertook a prospective cohort study to characterize the early natural history of HIV viral load and CD4(+) T lymphocyte counts in individuals with recent HIV seroconversion in India. CD4(+) T lymphocyte counts were prospectively measured for up to 720 days in 46 antiviral drug-naive persons with very early HIV infection, documented by HIV antibody seroconversion. HIV viral RNA levels were measured subsequently on reposited plasma samples from these same time points. The median viral load "set point" for Indian seroconverters was 28,729 RNA copies/ml. The median CD4(+) cell count following acute primary HIV infection was 644 cells/mm(3). Over the first 2 years since primary infection, the annual rate of increase in HIV viral load was +8274 RNA copies/ml/year and the annual decline in CD4 cell count was -120 cells/year. Although the viral "set point" was similar, the median trajectory of increasing viral load in Indian seroconverters was greater than what has been reported in untreated HIV seroconverters in the United States. These data suggest that the more rapid HIV disease progression described in resource-poor settings may be due to very early virological and host events following primary HIV infection. A rapid increase in viral load within the first 2 years after primary infection may have to be considered when applying treatment guidelines for antiretroviral therapy and opportunistic infection prophylaxis.