In resource limited settings non-availability of CD4 count facility at the site could adversely affect the ART roll out programme. Point of care CD4 enumerating equipments can make the CD4 count available at the site of care and improve the patients’ management considerably. This study is aimed at determining the utility of a Point of Care PIMA CD4 analyzer (Alere, Germany) in the field settings in India.

CD4+ T lymphocyte counts are the most important indicator of disease progression and success of antiretroviral treatment in HIV infection in resource limited settings. The nationwide reference range of CD4+ T lymphocytes was not available in India. This study was conducted to determine reference values of absolute CD4+ T cell counts and percentages for adult Indian population.

Background: Limited information is available on HIV-1 Indian clade C sensitivities to autologous antibodies during the course of natural infection. In the present study, a total of 37 complete envelope clones (Env) were amplified at different time points predominantly from the plasma of five Indian patients with recent HIV-1 infection and envelope-pseudotyped viruses were examined for their magnitude of sensitivity to autologous plasma antibodies during natural course of infection. Results: Variable low levels of neutralization were consistently detected with contemporaneous autologous plasma. In contrast to clade B and African clade C HIV-1 envelopes, Env clones obtained from four patients were found to be resistant to IgG1b12. The majority of the Env clones were resistant to 2G12 and 2F5 due to the absence of the minimal motifs required for antibody recognition, but were sensitive to 4E10. Nonetheless, Env clones from one patient were found to be sensitive to 2G12, atypical for clade C, and one Env clone exhibited unusual sensitivity to 17b, suggesting spontaneous exposure of CD4i epitopes. Phylogenetic analysis revealed that Env clones were closely clustered within patients. Variation in the potential N-linked glycosylation pattern also appeared to be different in patients over the course of infection. Interestingly, we found that the sensitivity of Envs to contemporaneous autologous NAbs correlated positively with increased sensitivity to soluble CD4 and inversely with anti-CD4 antibody and Envs with increased NAb sensitivity were able to efficiently infect HeLa cells expressing low CD4. Conclusion: Our data showed considerable variations in autologous neutralization of these early HIV-1 clade C Envs in each of these patients and indicate greater exposure to CD4 of Envs that showed increased autologous neutralization. Interestingly, Env clones obtained from a single patient at different time points were found to retain sensitivity to b12 antibody that binds to CD4 binding site in Env in contrast to Envs obtained from other patients. However, we did not find any association between increased b12 sensitivity of Envs obtained from this particular patient with their degree of exposure to CD4.

HIV-specific antibody-dependent cell cytotoxicity (ADCC) is likely to be important in governing protection from HIV and slowing disease progression. Little is known about the ADCC responses to HIV-1 subtype C. We characterized ADCC responses in HIV-1 subtype C infected Indian subjects with slow disease progression and identified the dominant antigenic regions recognized by these antibodies. ADCC responses were measured in plasma from 34 Long Term Non Progressors (LTNPs), who were asymptomatic and maintained CD4 count above 500 cells/mm3for the last seven years in absence of Antiretroviral therapy (ART), and 58 ART naïve progressors with CD4 count < 500 cells/mm3 against overlapping HIV-1 peptides using a flow cytometry-based antibody-dependent NK cell activation assay. The assay measured CD107a expression on NK cells as a marker of antibody-dependent NK cell activation and IFN- secretion by NK cells upon activation. The ADCC epitopes were mapped using the matrix of overlapping peptides. Indian LTNPs showed higher and broader ADCC responses compared to the progressors. The Env C and Tat-specific ADCC responses were associated with lower plasma viral load whereas the Env C responses were also associated with higher CD4 counts. Five of 10 LTNP responders targeted epitopes in the V3 region (amino acids 288-330) of Env-C. Additionally, three Tat regions were targeted by ADCC antibodies from LTNPs. ADCC responses were associated with slow HIV progression in Indian subtype C infected cohort. The frequently recognized peptides from the V3 loop of Env and the novel epitopes from Tat by the LTNPs warrants further study to understand the role of ADCC responses to these regions in control and prevention of HIV-1 infection

Natural killer (NK) cells may be important in modulating HIV replication in early course of HIV infection. The effector function of NK cells is finely tuned by a balance between signals delivered by activating and inhibitory receptors. However the influence of expression of these receptors on the early course of HIV replication and subsequent disease progression is not explored in context of HIV-1 C infection. The expression pattern of activating (NKp46,NKp44, NKp30, NKG2D,NKG2C) and inhibitory (CD158b, NKG2A and ILT2) receptors was determined in 20 patients with recent HIV-1 C infection within 3-7 months of acquiring HIV infection and was compared with the expression pattern in individuals with progressive (N=12), non progressive HIV-1C infection (LTNPs, N=12) and healthy seronegative individuals (N=20). The association of the expression of these receptors on the rate of disease progression was assessed using viral load set point in recently infected individuals as a marker of disease progression. The study showed that higher cytotoxic potency of NK cells was associated with low viral load set point in recent HIV infection (r=-0.701; p=0.0006) and higher CD4 counts (r=0.720; p=0.001). The expression of activating receptors (NKp46, NKp30 and NKG2D) on cytotoxic NK cells but not on regulatory NK cells was significantly associated with low viral set point(p< 0.01) and viral load in LTNPs (p< 0.01).The study also indicated that cytotoxic NK cells might show the ability to specifically lyse HIV infected CD4 cells. This data collectively showed that early and sustained higher expression of activating receptors on cytotoxic NK cells could be responsible for increased cytotoxicity, reduced viral burden and thus delaying the disease progression. The study to identify the influence of HIV on the molecular mechanism of the expression of these receptors will be helpful in further understanding of NK cell mediated control in early HIV infection.

Analysis of the human immunodeficiency virus type 1 (HIV-1) cytolytic T lymphocyte (CTL) epitopes recognized by the targeted population is critical f