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BACKGROUND: Bacille Calmette-Guérin (BCG) vaccine is protective against Tuberculosis (TB) in children, but its efficacy wanes with age. Consequently, determining if BCG revaccination augments anti-TB immunity in young adults in TB endemic regions is vital. METHODS: Two hundred healthy adults, BCG vaccinated at birth, were tested for their IFN-γ release assay (IGRA) status. Of these, 28 IGRA(+) and 30 IGRA(–) were BCG revaccinated, and 24 IGRA(+) and 23 IGRA(–) subjects served as unvaccinated controls. T and innate cell responses to mycobacterial antigens were analyzed by 14-color flow cytometry over 34 weeks. RESULTS: IFN-γ and/or IL-2 Ag85A- and BCG-specific CD4(+) and CD8(+) T cell responses were boosted by revacciantion at 4 and 34 weeks, respectively, and were > 2-fold higher in IGRA(+) compared with IGRA(–) vaccinees. Polyfunctional Ag85A, BCG, and mycobacterium tuberculosis (Mtb) latency Ag–specific (LTAg-specific) CD4(+) T cells expressing up to 8 cytokines were also significantly enhanced in both IGRA(+) and IGRA(–) vaccinees relative to unvaccinated controls, most markedly in IGRA(+) vaccinees. A focused analysis of Th17 responses revealed expansion of Ag85A-, BCG-, and LTAg-specific total IL-17A(+),IL-17F(+),IL-22(+), and IL-10(+) CD4(+) T cell effectors in both IGRA(+) and IGRA(–) subjects. Also, innate IFN-γ(+) NK/γδ/NKT cell responses were higher in both IGRA(+) and IGRA(–) vaccinees compared with controls. This is the first evidence to our knowledge that BCG revaccination significantly boosts antimycobacterial Th1/Th17 responses in IGRA(+) and IGRA(–) subjects. CONCLUSION: These data show that BCG revaccination is immunogenic in IGRA(–) and IGRA(+) subjects, implying that Mtb preinfection in IGRA(+) subjects does not impact immunogenicity. This has implications for public health and vaccine development strategies. FUNDING: This work was funded principally by DBT-NIH (BT/MB/Indo-US/HIPC/2013).

Chronic T cell activation is a hallmark of pulmonary tuberculosis (PTB). The mechanisms underpinning this important phenomenon are however, poorly elucidated, though known to rely on control of T effector cells (Teff) by regulatory T cells (Treg). Our studies show that circulating natural Treg cells in adults with PTB preserve their suppressive potential but Teff cells from such subjects are resistant to Treg-mediated suppression. We found this to be due to expansion of an activated Teff subset identified by Human Leukocyte Antigen (HLA)-DR expression. Sensitivity to suppression was restored to control levels by depletion of this subset. Comparative transcriptome analysis of Teff cells that contain HLA-DR+ cells versus the fraction depleted of this population identified putative resistance mechanisms linked to IFNG, IL17A, IL22, PD-L1 and β-chemokines CCL3L3, CCL4 expression. Antibody blocking experiments confirmed HLA-DR+ Teff cells, but not the fraction depleted of HLA-DR+ effectors, to be resistant to Treg suppression mediated via CCR5 and PD-L1 associated pathways. In the presence of HLA-DR+ Teff cells, activation of NFκB downstream of CCR5 and PD-L1 was perturbed. In addition, HLA-DR+ Teff cells expressed significantly higher levels of Th1/Th17 cytokines that may regulate Treg function through a reciprocal counter-balancing relationship. Taken together, our study provides novel insight on how activated HLA-DR+CD4+ T cells may contribute to disease associated inflammation by compromising Treg-mediated suppression in PTB., Author summary An important marker of progression to PTB following Mycobacterium tuberculosis (Mtb) infection in humans is elevated frequencies of HLA-DR+CD4+ T cells, reflecting chronic T cell activation. However, the mechanisms by which activated HLA-DR+CD4+ T cells contribute to disease process is not known. We show that CD25- HLA-DR+CD4+ memory Teff from PTB patients are resistant to suppression mediated by Treg cells. An unbiased transcriptome analysis identified several key pathways that contribute to this resistance. Specifically, presence of HLA-DR+CD4+ T cells renders the effector population resistant to CCR5 and PD-L1 mediated suppression by Treg cells. In addition, the HLA-DR+CD4+ memory Teff cells express elevated levels of Th1/Th17 cytokines known to counter-regulate and dampen Treg suppression. These findings provide fresh insight to disease process in TB and identify HLA-DR+ Teff resistant to Treg suppression as a potential functional marker of disease.

The functional heterogeneity of T cell responses to diverse antigens expressed at different stages of Mycobacterium tuberculosis (Mtb) infection, in particular early secreted versus dormancy related latency antigens expressed later, that distinguish subjects with latent (LTBI), pulmonary (PTB) or extrapulmonary (EPTB) tuberculosis remains unclear. Here we show blood central memory CD4 T-cell responses specific to Mtb dormancy related (DosR) latency, but not classical immunodominant secretory antigens, to clearly differentiate LTBI from EPTB and PTB. The polyfunctionality score integrating up to 31 DosR-specific CD4 T-cell functional profiles was significantly higher in LTBI than EPTB or PTB subjects. Further analysis of 256 DosR-specific T-cell functional profiles identified regulatory IL10 + Th17 cells (IL10+IL17A+IL17F+IL22+) to be significantly enriched in LTBI; in contrast to pro-inflammatory Th17 cells (IFNγ+IL17A+/IL10−) in the blood and lung of EPTB and PTB subjects respectively. A blood polyfunctional, Mtb DosR latency antigen specific, regulatory, central memory response is therefore a novel functional component of T-cell immunity in latent TB and potential correlate of protection.

The functional heterogeneity of T cell responses to diverse antigens expressed at different stages of Mycobacterium tuberculosis (Mtb) infection, in particular early secreted versus dormancy related latency antigens expressed later, that distinguish subjects with latent (LTBI), pulmonary (PTB) or extrapulmonary (EPTB) tuberculosis remains unclear. Here we show blood central memory CD4 T-cell responses specific to Mtb dormancy related (DosR) latency, but not classical immunodominant secretory antigens, to clearly differentiate LTBI from EPTB and PTB. The polyfunctionality score integrating up to 31 DosR-specific CD4 T-cell functional profiles was significantly higher in LTBI than EPTB or PTB subjects. Further analysis of 256 DosR-specific T-cell functional profiles identified regulatory IL10 + Th17 cells (IL10+IL17A+IL17F+IL22+) to be significantly enriched in LTBI; in contrast to pro-inflammatory Th17 cells (IFNγ+IL17A+/IL10−) in the blood and lung of EPTB and PTB subjects respectively. A blood polyfunctional, Mtb DosR latency antigen specific, regulatory, central memory response is therefore a novel functional component of T-cell immunity in latent TB and potential correlate of protection.

Monitoring of HIV-infected individuals on antiretroviral treatment (ART) ideally requires periodic viral load measurements to ascertain adequate response to treatment. While plasma viral load monitoring is widely available in high-income settings, it is rarely used in resource-limited regions because of high cost and need for sophisticated sample transport. Dried blood spot (DBS) as source specimens for viral load measurement has shown promise as an alternative to plasma specimens and is likely to be a useful tool for Indian settings. The present study was undertaken to investigate the performance of DBS in HIV-1 RNA quantification against the standard plasma viral load assay.Between April-June 2011, 130 samples were collected from HIV-1-infected (n=125) and non-infected (n=5) individuals in two district clinics in southern India. HIV-1 RNA quantification was performed from DBS and plasma using Abbott m2000rt system after manual RNA extraction. Statistical analysis included correlation, regression and Bland-Altman analysis.The sensitivity of DBS viral load was 97 per cent with viral loads3.0 log 10 copies/ml. Measurable viral load (3.0 log 10 copies/ml) results obtained for the 74 paired plasma-DBS samples showed positive correlation between both the assays (r=0.96). For clinically acceptable viral load threshold values of5,000 copies/ml, Bland-Altman plots showed acceptable limits of agreement (-0.21 to +0.8 log 10 copies/ml). The mean difference was 0.29 log 10 copies/ml. The cost of DBS was $2.67 lower compared to conventional plasma viral load measurement in the setting.The significant positive correlation with standard plasma-based assay and lower cost of DBS viral load monitoring suggest that DBS sampling can be a feasible and economical means of viral load monitoring in HIV-infected individual in India and in other resource-limited settings globally.

Introduction: Human APOBEC3G/F (hA3G/F) restricts retroviral replication through G-to-A hypermutations, which can generate drug-resistant progenies in vitro . The clinical relevance is still inconclusive. To bridge this gap, we aim to study the role of these hypermutations in evolution of drug resistance; we characterised hA3G/F-mediated hypermutations in the RT region of the pol gene of patients with or without antiretroviral therapy (ART). Methods: In 88 HIV-1-positive individuals, drug resistance genotyping was carried out in plasma virus and provirus by population sequencing. Hypermutations were determined by three different approaches using Hypermut 2.0 software, cluster analysis and APOBEC3G-mediated defectives indices. Clinical and demographic characteristics of these individuals were studied in relation to these hypermutations. Results: hA3G/F-mediated hypermutated sequences in proviral DNA, but not in plasma virus, were identified in 11.4% (10/88) subjects. Proviral hypermutations were observed more frequently in patients with ART failure than in ART-naive individuals ( p = 0.03). In therapy failure patients, proviral hypermutation were associated with greater intra-compartmental genetic diversity ( p

BACKGROUND Coreceptor switch from CCR5 to CXCR4 is considered to be less common in HIV-1 subtype C even in advanced stages of infection. In this study, we have examined viral genotypic coreceptor tropism and its clinical, virological, and host genetic determinants among perinatally infected children in India. METHODS Genotypic coreceptor tropism analysis was conducted on env V3 sequences using Geno2pheno with a threshold of 10% false-positive rate. A total of 473 sequences were obtained from 72 isolates amplified from children aged 2-17 years. Factors associated with viral tropism in subtype C infections were studied using logistic regression. RESULTS Among the samples, 98.6% (71 of 72) were HIV-1 subtype C. Coreceptor tropism analysis determined 81.7% (58 of 71) as R5 tropic, 9.9% (7 of 71) as X4 tropic, and 8.5% (6 of 71) as R5/X4 tropic or dual-tropic HIV-1 strains. Children with X4 or R5/X4 strains were more likely to be older than those with R5-tropic strains (P < 0.05), have lower CD4 counts (P < 0.05), and have viral populations with greater intrapopulation viral divergence (P < 0.01). Older age was a significant independent predictor for X4 or R5/X4 tropism in these children (P < 0.05). None were identified as being heterozygous or homozygous for the CCR5[INCREMENT]32 deletion. CONCLUSIONS The high prevalence of X4 and R5/X4 tropic strains among older perinatally infected children with HIV-1 subtype C in India indicate that this phenomenon is not uncommon as previously thought and suggest that coreceptor transition can occur with longer duration of infection and greater disease progression in this population of perinatally infected children living with HIV-1 subtype C.

Results Among those who had been on ART for a median period of 24 months 51 children (83.6%) achieved virological suppression. There were 10 children with virological failure, and only two amongst these manifested immunological failure. Nine children (90%) had reverse transcriptase-related DRMs, and none had protease inhibitor-related DRMs. The most frequent NRTI mutation was M184V (n=9) followed by two thymidine analogous associated mutations (TAMs) M41L and T215Y (n=2). The most frequent nNRTI mutations were K103N (n=6) and Y181C (n=3).

Background High plasma viremia in HIV-1 infection is associated with rapid CD4 cell decline and faster disease progression. Children with HIV infection have high viral loads, particularly in early childhood. In this study we sought to understand the relationship between duration of HIV-1 infection and viral dynamics among perinatally-infected children and adolescents in India along with transmitted drug resistance in this population. Methods During 2007–2011, cross-sectional samples were collected from ART-naïve children (n = 105) with perinatally-acquired HIV infection, aged 2–16 years from Bangalore, India. CD4 counts, viral load and in-house genotyping were performed and transmitted drug resistance mutations were identified using the World Health Organization recommendations for Surveillance of Drug Resistance Mutations (SDRM_2009) list. Results Among 105 children studied, 73.3% (77/105) were asymptomatic, but had a median viral load of 5.24 log copies/mL (IQR 4.62-5.66). In the adolescent age group, 54% (21/39) had high levels of viremia (median 5.14 log copies/mL) but were asymptomatic. HIV-1 subtyping identified 98% strains (103/105) as subtype C; one A1 and one unique recombinant form (URF). Transmitted NRTI resistance was 1.9% (2/105); NNRTI resistance was 4.8% (5/105) and overall prevalence of transmitted drug resistance was 5.7% (6/105). Conclusions The high burden of plasma viremia found among untreated asymptomatic adolescents needs to be addressed both from an individual angle to halt disease progression, and from a public health perspective to arrest horizontal transmission. The low level of transmitted drug resistance among perinatally-infected children is reassuring; however with improving ART access globally, regular genotyping surveillance is indicated.