Mohit Singla

Immune Response to Dengue Virus Infection in Pediatric Patients in New Delhi, India—Association of Viremia, Inflammatory Mediators and Monocytes with Disease Severity

Dengue virus, a mosquito-borne flavivirus, is a causative agent for dengue infection, which manifests with symptoms ranging from mild fever to fatal dengue shock syndrome. The presence of four serotypes, against which immune cross-protection is short-lived and serotype cross-reactive antibodies that might enhance infection, pose a challenge to further investigate the role of virus and immune response in pathogenesis. We evaluated the viral and immunological factors that correlate with severe dengue disease in a cohort of pediatric dengue patients in New Delhi. Severe dengue disease was observed in both primary and secondary infections. Viral load had no association with disease severity but high viral load correlated with prolonged thrombocytopenia and delayed recovery. Severe dengue cases had low Th1 cytokines and a concurrent increase in the inflammatory mediators such as IL-6, IL-8 and IL-10. A transient increase in CD14+CD16+ intermediate monocytes was observed early in infection. Sorting of monocytes from dengue patient peripheral blood mononuclear cells revealed that it is the CD14+ cells, but not the CD16+ or the T or B cells, that were infected with dengue virus and were major producers of IL-10. Using the Boruta algorithm, reduced interferon-α levels and enhanced aforementioned pro-inflammatory cytokines were identified as some of the distinctive markers of severe dengue. Furthermore, the reduction in the levels of IL-8 and IL-10 were identified as the most significant markers of recovery from severe disease. Our results provide further insights into the immune response of children to primary and secondary dengue infection and help us to understand the complex interplay between the intrinsic factors in dengue pathogenesis.

Characterization of Human CD8 T Cell Responses in Dengue Virus-Infected Patients from India

ABSTRACT Epidemiological studies suggest that India has the largest number of dengue virus infection cases worldwide. However, there is minimal information about the immunological responses in these patients. CD8 T cells are important in dengue, because they have been implicated in both protection and immunopathology. Here, we provide a detailed analysis of HLA-DR+ CD38+ and HLA-DR− CD38+ effector CD8 T cell subsets in dengue patients from India and Thailand. Both CD8 T cell subsets expanded and expressed markers indicative of antigen-driven proliferation, tissue homing, and cytotoxic effector functions, with the HLA-DR+ CD38+ subset being the most striking in these effector qualities. The breadth of the dengue-specific CD8 T cell response was diverse, with NS3-specific cells being the most dominant. Interestingly, only a small fraction of these activated effector CD8 T cells produced gamma interferon (IFN-γ) when stimulated with dengue virus peptide pools. Transcriptomics revealed downregulation of key molecules involved in T cell receptor (TCR) signaling. Consistent with this, the majority of these CD8 T cells remained IFN-γ unresponsive even after TCR-dependent polyclonal stimulation (anti-CD3 plus anti-CD28) but produced IFN-γ by TCR-independent polyclonal stimulation (phorbol 12-myristate 13-acetate [PMA] plus ionomycin). Thus, the vast majority of these proliferating, highly differentiated effector CD8 T cells probably acquire TCR refractoriness at the time the patient is experiencing febrile illness that leads to IFN-γ unresponsiveness. Our studies open novel avenues for understanding the mechanisms that fine-tune the balance between CD8 T cell-mediated protective versus pathological effects in dengue. IMPORTANCE Dengue is becoming a global public health concern. Although CD8 T cells have been implicated both in protection and in the cytokine-mediated immunopathology of dengue, how the balance is maintained between these opposing functions remains unknown. We comprehensively characterized CD8 T cell subsets in dengue patients from India and Thailand and show that these cells expand massively and express phenotypes indicative of overwhelming antigenic stimulus and tissue homing/cytotoxic-effector functions but that a vast majority of them fail to produce IFN-γ in vitro. Interestingly, the cells were fully capable of producing the cytokine when stimulated in a T cell receptor (TCR)-independent manner but failed to do so in TCR-dependent stimulation. These results, together with transcriptomics, revealed that the vast majority of these CD8 T cells from dengue patients become cytokine unresponsive due to TCR signaling insufficiencies. These observations open novel avenues for understanding the mechanisms that fine-tune the balance between CD8-mediated protective versus pathological effects.

Rapid antigen tests for dengue virus serotypes and Zika virus in patient serum

A low-cost, equipment-free rapid antigen test distinguishes dengue virus serotypes and Zika virus in patient sera without detectable cross-reactivity. Distinguishing dengue from Zika More than mere summer pests, mosquitoes can transmit viruses, such as dengue and Zika. Diagnosing infections of these related flaviviruses can be difficult because of cross-reactivity in diagnostic tests. Bosch et al. developed monoclonal antibodies to detect viral nonstructural 1 (NS1) protein antigens specific to dengue and Zika. Incorporating the antibodies into an immunochromatography format yielded a rapid diagnostic assay that produces a visual readout in the presence of NS1. The assay identified the four dengue serotypes and Zika viral infections without cross-reaction when testing human serum samples from endemic areas in Central and South America and India. This approach could be useful for developing rapid diagnostics for other emerging pathogens. The recent Zika virus (ZIKV) outbreak demonstrates that cost-effective clinical diagnostics are urgently needed to detect and distinguish viral infections to improve patient care. Unlike dengue virus (DENV), ZIKV infections during pregnancy correlate with severe birth defects, including microcephaly and neurological disorders. Because ZIKV and DENV are related flaviviruses, their homologous proteins and nucleic acids can cause cross-reactions and false-positive results in molecular, antigenic, and serologic diagnostics. We report the characterization of monoclonal antibody pairs that have been translated into rapid immunochromatography tests to specifically detect the viral nonstructural 1 (NS1) protein antigen and distinguish the four DENV serotypes (DENV1–4) and ZIKV without cross-reaction. To complement visual test analysis and remove user subjectivity in reading test results, we used image processing and data analysis for data capture and test result quantification. Using a 30-μl serum sample, the sensitivity and specificity values of the DENV1–4 tests and the pan-DENV test, which detects all four dengue serotypes, ranged from 0.76 to 1.00. Sensitivity/specificity for the ZIKV rapid test was 0.81/0.86, respectively, using a 150-μl serum input. Serum ZIKV NS1 protein concentrations were about 10-fold lower than corresponding DENV NS1 concentrations in infected patients; moreover, ZIKV NS1 protein was not detected in polymerase chain reaction–positive patient urine samples. Our rapid immunochromatography approach and reagents have immediate application in differential clinical diagnosis of acute ZIKV and DENV cases, and the platform can be applied toward developing rapid antigen diagnostics for emerging viruses.

Zinc Supplementation for One Year Among Children with Cystic Fibrosis Does Not Decrease Pulmonary Infection

BACKGROUND: Children with cystic fibrosis may have a deficiency of micronutrients, including zinc, which may affect their susceptibility to infections. There is a paucity of data on zinc supplementation among children with cystic fibrosis. We hypothesized that a pharmacologic dose of zinc administered daily for 12 months would reduce the need for antibiotics by 50%. METHODS: This double-blind randomized placebo-controlled trial was conducted among children with cystic fibrosis to assess the effect of zinc supplementation on the need for antibiotics and pulmonary function tests. The children, age 5–15 y, of either sex, received either 30-mg zinc tablets or similar looking placebo tablets daily in addition to standard care. They were followed up every month for a period of 12 months and whenever they had pulmonary exacerbations. Their serum zinc was estimated at baseline and at 12 months of enrollment. During each visit, the children underwent a pulmonary function test and sputum culture. RESULTS: Of a total of 43 children screened, 40 were enrolled, and of them, 37 completed the study. The median (interquartile range) number of days of the administration of antibiotics over 12 months of follow-up among the children receiving zinc was 42 (14–97) d. In the placebo group, it was 38 (15–70) d (P = .79). There were no significant differences in the percent-of-predicted FEV1 or change in FEV1 values at 12 months (P = .44). The number of children in whose respiratory specimens Pseudomonas was isolated was similar for the 2 groups at different time intervals. The adverse events reported were similar in the 2 groups. CONCLUSION: We did not find any significant difference in the need for antibiotics, pulmonary function tests, hospitalization, colonization with Pseudomonas, or the need for antibiotics for children with cystic fibrosis receiving zinc supplementation of 30 mg/d.

Dengue Virus Entry and Replication Does Not Lead to Productive Infection in Platelets

Abstract Thrombocytopenia is a characteristic feature during the acute phase of dengue infection and has been found to associate with vascular leakage in severe dengue. Although dengue antigens have been observed in platelets, there is no strong evidence to suggest a direct infection of platelets by dengue virus as a contributing factor for thrombocytopenia. We show that dengue virus can enter platelets but replicate viral ribonucleic acid to a minimal extent and, therefore, cannot produce infectious virus. Dengue antigen was undetectable in platelets isolated from dengue patients; however, we observed an increase in CD14+CD16+ monocyte-platelet complexes, suggesting a mechanism for platelet clearance.

Immunologic effect of zinc supplementation in HIV-infected children receiving highly active antiretroviral therapy: a randomized, double-blind, placebo-controlled trial.

Background:We conducted this study to assess the immunologic effect of daily 20 mg zinc supplementation for 24 weeks in HIV-infected children older than 6 months receiving highly active antiretroviral therapy (ART). Methods:Fifty-two HIV-infected children older than 6 months in whom ART was initiated were randomized to receive either 20 mg of zinc or placebo for a period of 24 weeks. Children underwent clinical examination, anthropometry, and laboratory evaluations: CD4% and count, viral load, and serum zinc level at baseline, 12 weeks, and 24 weeks. The primary outcome evaluated was CD4% value at the end of 12 and 24 weeks of study intervention in the enrolled children. Results:Of 52 children enrolled, 49 completed the study. The median CD4% value rose from 10% to 23% at 12 weeks and to 24.5% at 24 weeks in the zinc group, whereas in the placebo group, the value rose from 11% to 20% at 12 weeks and to 22% at 24 weeks (P = 0.188 for comparison between the zinc and the placebo group at 12 wk and P = 0.3 for comparison at 24 wk). The median (interquartile range) log reductions in the viral load at 12 weeks in the 2 arms were similar at 12 (P = 0.84) and 24 weeks (P = 0.43). Conclusions:Supplementation of 20 mg zinc daily for 24 weeks did not have any statistically significant effect on the increase in CD4%, decrease in viral load, anthropometric indices, and morbidity profile in HIV-infected children started on ART.

Pharmacokinetics of isoniazid, rifampicin, pyrazinamide and ethambutol in HIV-infected Indian children.

SETTING Co-infection with the human immunodeficiency virus (HIV) may lead to inadequate plasma concentrations of anti-tuberculosis drugs in children with tuberculosis (TB). OBJECTIVE To describe the influence of HIV infection on the pharmacokinetics of isoniazid, rifampicin, pyrazinamide and ethambutol in children. DESIGN Prospective drug estimation study in two cohorts of children: HIV-infected (n = 24) and non-HIV-infected (n = 32) with TB. Dosages used were based on earlier World Health Organization recommendations. All four drugs were estimated simultaneously using liquid chromatography mass spectrometry. RESULTS The HIV-TB co-infected children had a mean age of 105.9 months (standard deviation 43.1); there were 10 girls (41.7%). The maximum plasma concentration (Cmax), time taken to achieve Cmax, area under curve from 0-4 h and 2 h concentrations of isoniazid (INH), rifampicin (RMP) and pyrazinamide (PZA) were not affected by the HIV status of the children. Ethambutol (EMB) concentrations were lower in HIV-TB co-infected children. Inadequate 2 h concentrations of INH, RMP and EMB were found in the majority of the children in both groups. PZA concentrations were adequate in almost all children. Younger age and lower dose were associated with lower 2 h concentrations of INH and RMP. CONCLUSION Inadequate concentrations of INH, RMP and EMB in both HIV-TB-infected and non-HIV-infected children provide support for the recently revised recommended doses of INH and RMP. EMB levels were lower in HIV-infected children; however, more studies are needed to validate this observation.

Evolution of cross-neutralizing antibodies and mapping epitope specificity in plasma of chronic HIV-1-infected antiretroviral therapy-naïve children from India

Delineating the factors leading to the development of broadly neutralizing antibodies (bnAbs) during natural HIV-1 infection and dissecting their epitope specificities generates useful information for vaccine design. This is the first longitudinal study to assess the plasma-neutralizing antibody response and neutralizing determinants in HIV-1-infected children from India. We enrolled 26 and followed up 20 antiretroviral therapy (ART)-naïve, asymptomatic, chronic HIV-1-infected children. Five (19.2 %) baseline and 10 (50 %) follow-up plasma samples neutralized ≥50 % of subtypes A, B and C tier 2 viruses at an ID50 titre ≥150. A modest improvement in neutralization breadth and potency was observed with time. At baseline, subtype C-specific neutralization predominated (P=0.026); interestingly, follow-up samples exhibited cross-neutralizing activity. Epitope mapping revealed V3C reactive antibodies with significantly increased Max50 binding titres in follow-up samples from five infected children; patient #4s plasma antibodies exhibited V3-directed neutralization. A salient observation was the presence of CD4 binding site (CD4bs)-specific NAbs in patient #18 that improved with time (1.76-fold). The RSC3 wild-type (RSC3WT) protein-depleted plasma eluate of patient #18 demonstrated a more than 50% ID50 decrease in neutralization capacity against five HIV-1 pseudoviruses. Further, the presence of CD4bs-neutralizing determinants in patient #18s plasma was confirmed by the neutralizing activity demonstrated by the CD4bs-directed IgG fraction purified from this plasma, and competition with sCD4 against JRFLgp120, identifying this paediatric donor as a potential candidate for the isolation of CD4bs-directed bnAbs. Overall, we observed a relative increase in plasma-neutralizing activity with time in HIV-1-infected children, which suggests that the bnAbs evolve.

Pharmacokinetics of nevirapine, stavudine and lamivudine in Indian HIV-infected children receiving generic fixed dose combinations

ObjectiveTo determine the trough and two hour plasma levels of nevirapine, stavudine, and lamivudine when administered in fixed dose combinations (FDC).DesignCross sectionalSettingTertiary care hospital in Northern India.Participants79 HIV-infected children receiving antiretroviral therapy with FDCs for more than month.InterventionTwo-point sampling (0 and 2 hours after the morning dose).Outcome measuresPlasma concentrations of all three drugs were simultaneously assayed by liquid chromatography/mass spectroscopy.ResultsMajority (77%) of children were receiving fixed dose combination of stavudine, lamivudine, nevirapine in the ratio of 6:30:50mg. The median (IQR) trough and 2-hour plasma levels (μg/mL) of nevirapine, stavudine and lamivudine were 5.2 (4.0, 6.3) and 7.9 (6.0, 9.7); 0.1 (0.06, 0.16) and 1.1 (0.59, 1.6); 0.1 (0.02, 0.2) and 2.5 (1.4, 3.1), respectively. Very few children had sub-therapeutic plasma drug levels of stavudine (2.5%), lamivudine (7.6%) and nevirapine (10%). Inadequate viral suppression at 6 months follow up was significantly associated with initial high viral load, low CD4 percentage at the time of enrolment in study, and lower doses of lamivudine and stavudine.ConclusionThe currently available generic pediatric fixed dose antiretroviral combinations in India provide adequate drug exposure in majority of children.

Production of cross neutralizing single chain fragment variables (scFv) from HIV-1 infected Indian children

Methods Nine ART drug naive HIV-1 subtype c infected children were recruited. PBMCs were isolated from all the subjects and pooled. RNA was isolated and cDNA was synthesized followed by amplification of VH and VL chain genes and scFv construction. A human recombinant scFv phage display library of 108 clones was constructed. Diversity of the phage library was checked by DNA sequencing and biopanned with RSC3 core antigen. 60 random clones were screened by phage ELISA. Expression of the scFvs was assessed by SDS-PAGE and Western blotting.