Elevated Complement Activation Fragments and C1q-Binding Circulating Immune Complexes in Varied Phases of Chikungunya Virus Infection.

Chikungunya virus (CHIKV) is a causative agent of a disease continuum, ranging from an acute transient chikungunya fever to chronic incapacitating viral arthralgia. The interaction between anti-CHIKV antibodies and the complement system has recently received attention. However, the contribution of complement activation in CHIKV-induced pathologies has not been fully elucidated. The present study was undertaken to delineate the possible contribution of complement activation in CHIKV-induced disease progression. In this study, using plasma specimens of chikungunya patients in the acute, chronic, and recovered phases of infection, we explicated the involvement of complement activation in CHIKV disease progression by ELISAs and Bio-Plex assays. Correlation analysis was carried out to demonstrate interrelation among C1q-binding IgG-containing circulating immune complexes (CIC-C1q), complement activation fragments (C3a, C5a, sC5b-9), and complement-modulated pro-inflammatory cytokines (IL-1ß, IL-18, IL-6, and TNF-α). We detected elevated complement activation fragments, CIC-C1q, and complement-modulated cytokines in the varied patient groups compared with the healthy controls, indicating persistent activation of the complement system. Furthermore, we observed statistically significant correlations among CIC-C1q with complement activation fragments and C3a with complement modulatory cytokines IL-1ß, IL-6, and IL-18 during the CHIKV disease progression. Taken together, the current data provide insight into the plausible association between CICs, complement activation, subsequent complement modulatory cytokine expression, and CHIKV etiopathology.

Association of inhibitory NKG2A and activating NKG2D natural killer cell receptor genes with resistance to SARS-CoV-2 infection in a western Indian population.

We have evaluated the association of polymorphisms in the intronic variable-number tandem repeat (VNTR) regions of the human NKG2D, NKG2A, and IL-1RN genes with resistance and/or susceptibility to SARS-CoV-2 infection in a total of 209 patients with SARS-CoV-2 infection (125 asymptomatic patients and 84 symptomatic patients with mild symptoms) and 355 healthy controls, using the PCR-RFLP method. The genotypic and allelic frequency distributions for an IL-1RN (VNTR) single-nucleotide polymorphism (SNP) were found to be comparable among the patient groups. Overall, in SARS-CoV-2 patients, NKG2A (rs2734440) showed a protective association in the codominant [(A/A vs. A/G): (OR = 0.53, 95% CI = 0.34-0.83, p = 0.006)], recessive [(A/A vs. A/G+G/G): (OR = 0.6, 95% CI = 0.39-0.92, p = 0.02)] and over-dominant [(A/A+G/G vs. A/G): (OR = 0.57, 95% CI = 0.38-0.84, p = 0.005)] models. Similarly, NKG2D (rs7980470) showed a protective association in the codominant [(A/A vs. A/G): (OR = 0.46, 95% CI = 0.3-0.7, p = 0.0003), codominant (A/A vs. G/G): (OR = 0.54, 95% CI = 0.31-0.71, p = 0.027)], recessive [(A/A vs. A/G+G/G): (OR = 0.47, 95% CI = 0.32-0.7, p = 0.0001) and over-dominant [(A/A+G/G vs. A/G): (OR = 0.56, 95% CI = 0.38-0.82, p = 0.003)] models. At the allelic level, there was a higher frequency of the "G" allele of NKG2D (rs7980470) in healthy controls than in patients with SARS-CoV-2 infection, suggesting that individuals with the "G" allele in the intronic region of NKG2D are likely to be protected against SARS-CoV-2 infection. Overall, our data suggest that polymorphisms in the host NKG2D and NKG2A genes have a protective role in SARS-CoV-2 infection, although the functional impact of these polymorphisms on control of SARS-CoV-2 infection remains unknown.

Peripheral lymphocyte subset alteration in patients with COVID-19 having differential clinical manifestations.

Background & objectives: The COVID-19 disease profile in Indian patients has been found to be different from the Western world. Changes in lymphocyte compartment have been correlated with disease course, illness severity and clinical outcome. This study was aimed to assess the peripheral lymphocyte phenotype and subset distribution in patients with COVID-19 disease from India with differential clinical manifestations. Methods: Percentages of peripheral lymphocyte subsets were measured by flow cytometry in hospitalized asymptomatic (n=53), mild symptomatic (n=36), moderate and severe (n=30) patients with SARS-CoV-2 infection, recovered individuals (n=40) and uninfected controls (n=56) from Pune, Maharashtra, India. Results: Percentages of CD4+Th cells were significantly high in asymptomatic, mild symptomatic, moderate and severe patients and recovered individuals compared to controls. Percentages of Th memory (CD3+CD4+CD45RO+), Tc memory (CD3+CD8+CD45RO+) and B memory (CD19+CD27+) cells were significantly higher in the recovered group compared to both asymptomatic, mild symptomatic patient and uninfected control groups. NK cell (CD56+CD3-) percentages were comparable among moderate +severe patient and uninfected control groups. Interpretation & conclusions: The observed lower CD4+Th cells in moderate+severe group requiring oxygen support compared to asymptomatic+mild symptomatic group not requiring oxygen support could be indicative of poor prognosis. Higher Th memory, Tc memory and B memory cells in the recovered group compared to mild symptomatic patient groups might be markers of recovery from mild infection; however, it remains to be established if the persistence of any of these cells could be considered as a correlate of protection.

An outbreak of hepatitis E in Yavatmal, India, 2019.

Hepatitis E, a public health concern in developing countries, frequently presents in epidemic, as well as in sporadic forms. This study investigated an outbreak of viral hepatitis at Yavatmal, Maharashtra, India in March 2019. Blood samples from 10 patients were received at Indian Council of Medical Research-National Institute of Virology, Pune to test for the presence of enterically transmitted hepatitis viruses. Subsequently, 49 suspected cases were screened for anti-hepatitis E virus (HEV)/hepatitis A virus (HAV) immunoglobulin M and immunoglobulin G (IgG) antibodies, alanine amino-transferase levels and HEV RNA. Water samples were screened for HEV and HAV RNA followed by phylogenetic analysis. Overall 32 of 49 (65.3%) suspected cases had recent acute HEV infection, while dual infection with HAV was noted in one case (2.04%). Forty-eight of 49 suspected cases were positive for anti-HAV IgG antibodies indicative of previously acquired immunity against HAV. Water samples had evidence of HEV contamination as detected by reverse transcription-polymerase chain reaction. Sequencing of HEV RNA from both patients (n = 2) and water samples (n = 5) indicated HEV genotype 1 to be the etiological agent of this outbreak. Serological and molecular evidence confirmed HEV as the etiology. Mixing of contaminated drain water with the domestic water supply may have triggered this outbreak. Subsequent changing of the defaulted water pipelines and its segregation from drain pipelines by the health authorities resulted in progressive decline of this outbreak. Despite the limitations, periodic surveillance of HEV exposure pattern and reporting of small outbreaks would supplement to the global disease burden data of hepatitis E.

Cyclophilin A: a possible host modulator in Chandipura virus infection.

Chandipura virus (CHPV), belonging to the genus Vesiculovirus of the family Rhabdoviridae, has been identified as one of the causes of pediatric encephalitis in India. Currently, neither vaccines nor therapeutic drugs are available against this agent. Considering that the disease progresses very fast with a high mortality rate, working towards the development of potential therapeutics against it will have a public health impact. Although the use of viral inhibitors as antiviral agents is the most common way to curb virus replication, the mutation-prone nature of viruses results in the development of resistance to antiviral agents. The recent development of proteomic platforms for analysis of purified viral agents has allowed certain upregulated host proteins that are involved in the morphogenesis and replication of viruses to be identified. Thus, the alternative approach of inhibition of host proteins involved in the regulation of virus replication could be explored for their therapeutic effectiveness. In the current study, we have evaluated the effect of inhibition of cyclophilin A (CypA), an immunophilin with peptidyl-prolyl cis/trans-isomerase activity, on the replication of CHPV. Treatment with cyclosporin A, used in vitro for the inhibition of CypA, resulted in a 3-log reduction in CHPV titer and an undetectable level of CypA in comparison to an untreated control. An in silico analysis of the interaction of the CHPV nucleoprotein with the human CypA protein showed stable interaction in molecular docking and molecular dynamics simulations. Overall, the results of this study suggest a possible role of CypA in facilitating CHPV replication, thus making it one of the potential host factors to be explored in future antiviral studies.

Pro-inflammatory CXCL-10, TNF-α, IL-1ß, and IL-6: biomarkers of SARS-CoV-2 infection.

Currently, the world is witnessing the pandemic of COVID-19, a disease caused by the novel coronavirus SARS-CoV-2. Reported differences in clinical manifestations and outcomes in SARS-CoV-2 infection could be attributed to factors such as virus replication, infiltration of inflammatory cells, and altered cytokine production. Virus-induced aberrant and excessive cytokine production has been linked to the morbidity and mortality of several viral infections. Using a Luminex platform, we investigated plasma cytokine and chemokine levels of 27 analytes from hospitalized asymptomatic (n = 39) and mildly symptomatic (n = 35) SARS-CoV-2-infected patients (in the early phase of infection), recovered individuals (45-60 days postinfection) (n = 40), and uninfected controls (n = 36) from the city of Pune located in the state of Maharashtra in India. Levels of the pro-inflammatory cytokines IL-1ß, IL-6, and TNF-α and the chemokine CXCL-10 were significantly higher, while those of the antiviral cytokines IFN-γ and IL-12 p70 were significantly lower in both asymptomatic and mildly symptomatic patients than in controls. Comparison among the patient categories revealed no difference in the levels of the cytokines/chemokines except for CXCL-10 being significantly higher and IL-17, IL-4, and VEGF being significantly lower in the mildly symptomatic patients. Interestingly, levels of all key analytes were significantly lower in recovered individuals than in those in both patient categories. Nevertheless, the level of CXCL10 was significantly higher in the recovered patients than in the controls, indicating that the immune system of SARS-CoV-2 patients may take a longer time to normalize. Our data suggest that IL-6, IL-1ß, TNF-α, CXCL-10, and reduced antiviral cytokines could be used as biomarkers of SARS-CoV-2 infection.

Alternative pathway of complement activation has a beneficial role against Chandipura virus infection.

The complement system is a critical component of both innate and adaptive immune responses. It has both protective and pathogenic roles in viral infections. There are no studies regarding the role of complement system in Chandipura virus (CHPV) infection. The current study has investigated the role of complement pathways in the in vitro neutralization of CHPV in Vero E6 cells. Using normal human serum (NHS), heat-inactivated serum (HIS), human serum deficient of complement factor, respective reconstituted serum, assays like in vitro neutralization, real-time PCR, and flow cytometry-based tissue culture-based limited dose assay (TC-LDA) were carried out for assessing the activation of different complement pathways. NHS from 9/10 donors showed complement dependent neutralization, reduction in viral load and decrease in percentage of CHPV-positive cells compared to their HIS counterparts. EGTA or EDTA pretreatment experiments indicated that CHPV neutralization proceeds through the alternative pathway of the complement activation. Our data showed a strong dependence on C3 for the in vitro neutralization of CHPV. Disparity in CHPV neutralization levels between factor B-deficient and reconstituted sera could be attributed to amplification loop/"tick-over" mechanism. Assays using C3, C5, and C8 deficient sera indicated that complement-mediated CHPV neutralization and suppression of CHPV infectivity are primarily through C3 and C5, and not dependent on downstream complement factor C8. With no specific anti-viral treatment/vaccine against Chandipura, the current data, elucidating role of human complement system in the neutralization of CHPV, may help in designing effective therapeutics.

Hepatitis E virus seroprevalence among blood donors in Pune, India.

BACKGROUND: Blood transfusion is a recently reported route of hepatitis E virus (HEV) transmission. It is a bigger concern in regions where large-scale HEV genotype 1 infections occur causing more severe disease. The present study aims to assess the prevalence and rate of HEV infection in the blood donors of Pune, India. MATERIALS AND METHODS: A total of 2447 healthy blood donors were screened for anti-HEV IgG and IgM antibodies. Anti-HEV IgM antibody positives were further subjected to alanine aminotransferase measurement, HEV RNA detection, viral load quantification and phylogenetic analysis. RESULTS: Anti-HEV seroprevalence rate was 17.70%, while IgM prevalence rate was 0.20%. An age dependent increase in IgG seropositive rate was observed. Two of five IgM-positives tested positive for HEV RNA. The viral load ranged from 3.5 × 104 to 4.6 × 105 copies/mL and belonged to HEV genotype 1. CONCLUSIONS: HEV prevalence rate of 17.70% in the blood donors of Pune, India, a developing country, goes at par with the developed countries. Current data of 0.20% (5 of 2447) blood donors positive for anti-HEV IgM and two of them being HEV RNA positive suggest a need for consideration of cost-effective evaluation towards pooled HEV RNA testing in blood banks.

Association of IL1RN VNTR polymorphism with chikungunya infection: A study from Western India.

Chikungunya, caused by the chikungunya virus (CHIKV) mostly presents as acute and chronic articular inflammatory manifestations. Interleukin 1 receptor antagonist (IL-1RN) is a potent endogenous competitive inhibitor of IL-1α and 1ß and has an anti-inflammatory role. The present study evaluated the possible association of IL1RN variable number tandem-repeat (VNTR) alleles and genotypes, and CHIKV stimulated IL-1RN cytokine production with resistance and/or susceptibility to chikungunya infection and disease state in 224 patients with chikungunya (61 patients with acute chikungunya and 163 patients with chronic chikungunya) and 355 healthy controls. Polymerase chain reaction, CHIKV stimulated cytokine assay and luminex platform were used for assessing polymorphism and protein levels respectively. The study revealed a significant association of IL1RN*1/*1 genotype under recessive genetic model with the risk of developing chikungunya infection. Our findings also indicated that IL1RN *2 allele under dominant mode was associated with protection to chronic chikungunya. The results also revealed a higher production of IL-1 RN protein in patients with chronic chikungunya. To conclude, the results suggest the association of ILRN VNTR polymorphism and IL-RN protein levels with chronic chikungunya.

Identification of a conserved neutralizing epitope in the G-protein of Chandipura virus.

Chandipura virus (CHPV), associated with an encephalitic illness in humans, has caused multiple outbreaks with high mortality in central and western India in recent years. The present study compares surface glycoprotein (G-protein) from prototype and recent outbreak strains using in silico tools and in vitro experiments. In silico epitope predictions (B-cell and T-helper cell) for the sequences, 3D structure prediction and comparison of the G-proteins of the strains: I653514 (Year 1965), CIN0327 (Year 2003) and 148974 (Year 2014) revealed that the CHPV G-protein is stable and antigenic determinants are conserved. A monoclonal antibody developed against strain CIN0327 (named NAbC) was found to neutralize prototype I653514 as well as the currently circulating strain 148974. In silico antigen-antibody interaction studies using molecular docking of predicted structures of NAbC and G-proteins of various CHPV strains led to the identification of a conserved neutralizing epitope in the fusion domain of G-protein, which also contained a putative T-helper peptide. The identification of a conserved neutralizing epitope in domain IV (fusion domain amino acids 53 to 172) of CHPV G-protein is an important finding that may have the scope towards the development of protective targets against CHPV infection.

Regulation of the chikungunya-virus-induced innate inflammatory response by protein tyrosine phosphatase non-receptor 6 in muscle cells.

Chikungunya virus (CHIKV)-induced myositis is an emerging affliction with high incidence globally. Given the essential regulatory role of protein tyrosine phosphatase non-receptor 6 (PTPN6) in virus-induced myositis, the expression of the PTPN6 and TNF-α genes in a CHIKV-infected muscle cell line was examined by quantitative PCR, and the expression of PTPN6 and STAT 3 was examined by immunoblotting. In addition, the effect of PTPN6 siRNA treatment on TNF-α gene expression was assessed. Increased higher expression of PTPN6 and TNF-α, and significant upregulation of TNF-α upon PTPN6 siRNA treatment were observed, suggesting that CHIKV has the ability to induce host PTPN6 gene expression, which may lead to a decreased pro-inflammatory immune response in the host.

Envelope specific T cell responses & cytokine profiles in chikungunya patients hospitalized with different clinical presentations.

BACKGROUND & OBJECTIVES: Since the 2006 massive outbreaks, chikungunya (CHIK) is a major public health concern in India. The aim of this study was to assess envelope specific immune responses in patients with chikungunya infection. METHODS: This study included 46 hospitalized patients with chikungunya virus infection (encephalitis, n=22, other systemic involvement, OSI, n=12, classical, n=12) and six controls from Ahmedabad city, Gujarat, India. T cell responses and the levels of Th1, pro/ anti-inflammatory cytokines against the CHIK virus envelope antigens were assessed by lymphocyte proliferation assay and by cytometric bead array in flow cytometry, respectively. RESULTS: Lymphoproliferative response was uniform among the patients. Comparisons of cytokines revealed significantly higher levels of interleukin (IL)-4 and IL-5 in encephalitis, OSI and classical patients versus controls. The levels of tumour necrosis factor (TNF)-α were higher in classical patients categories compared to the controls. Interferon (IFN)-γ levels were lower in encephalitis patients versus control. INTERPRETATION & CONCLUSIONS: Our findings showed recognition of T cell epitopes on the envelope region of chikungunya virus by all patient categories. Lower level of IFN-γ may be associated with the severity of disease in these patients.

Broadly Reactive SARS-CoV-2-Specific T-Cell Response and Participation of Memory B and T Cells in Patients with Omicron COVID-19 Infection.

January 2022 onward, India witnessed a sudden increase in Omicron COVID-19 infections, having a mild course that prompted us to identify the key host factors/immune molecules modulating disease course/outcomes. The current study evaluated the percentages of lymphocyte subsets by flowcytometry, SARS-CoV-2 specific T-cell immune response by ELISPOT, estimation of plasma cytokine/chemokine levels on a Bio-plex Multiplex Immunoassay System and anti-SARS-CoV-2 IgG levels by enzyme-linked immunosorbent assay in 19 mild Omicron infected patients, 45 mild SARS-CoV-2 (2020) patients and 36 uninfected controls from India. Natural killer cells, B and memory B cells were high in vaccinated and total Omicron-infected patients groups compared to the mild SARS-CoV-2 (2020) patient group, while CD8+ T cells were high in total Omicron-infected patients group compared to the uninfected control group (p < 0.05 each). Omicron-infected patients had T-cell response against SARS-CoV-2 whole virus, S1 proteins (wild type and delta variant) in 10 out of 17 (59%), 10 out of 17 (59%), and 8 out of 17 (47%), respectively. The current study of Omicron-infected patients elucidates broadly reactive antibody, T-cell response, and participation of memory B and T cells induced by vaccination/natural infection. The limited effect of Omicron's mutations on T-cell response is suggestive of protection from severity. Pro-inflammatory IL-6, IFN-γ, chemokines CCL-2, CCL-3, CCL-4, CCL-5, and IL-8 as potential biomarkers of Omicron infection may have future diagnostic importance. The cellular immune response data in Omicron-infected patients with parental Omicron lineage could serve as a starting point to define the readouts of protective immunity against circulating Omicron subvariants.

Regulatory Role of B Cells and Its Subsets in Hepatitis E Virus Infection.

Antibodies as well as memory B cells are the potential correlates of a protective immune response against hepatitis E virus (HEV) infection. Literature on the role of B regulatory cells (Bregs) in acute viral infections is limited. We have evaluated the role of IL-10 expressing Bregs in HEV infection. A total of 108 acute hepatitis E patients, 55 hepatitis E recovered individuals and 128 HEV naïve healthy controls were enrolled. The percentages of peripheral CD19+, immature CD19+CD24hiCD38hi, mature CD19+CD24intCD38int and memory CD19+CD24hiCD38- B cells were analyzed by flowcytometry. Intracellular cytokine staining for IL-10 and TGF-ß, HEV-rORF2p specific T cell response (IFN-γ expression) pre/post IL-10/IL-10R blocking and CD19+IL-10+ B cells-depletion based assays were carried out to assess the functionality of Bregs. The percentage of HEV-rORF2p specific immature B cell phenotype was significantly higher in acute hepatitis E patients compared to hepatitis E recovered individuals and controls. Significantly higher IL-10 expression on B and HEV-rORF2p stimulated immature B cells of acute hepatitis E patients compared to controls indicated that Bregs are functional and HEV-rORF2p specific. Enhanced IFN-γ expression on CD8+ T cells upon IL-10/IL-10R blocking and also post CD19+IL-10+ B cells depletion suggested that CD3+CD8+IFN-γ + T cells corroborate the regulatory potential of Bregs via IL-10 dependent mechanism. We have identified HEV specific functional, immature CD19+CD24hiCD38hi B cells having IL-10 mediated regulatory activities and a potential to modulate IFN-γ mediated T cell response in Hepatitis E. The prognostic/pathogenic role of Bregs in recovery from severe hepatitis E needs evaluation.

Design of a multi-epitope peptide vaccine candidate against chandipura virus: an immuno-informatics study.

Chandipura virus (CHPV) is an emerging pathogen responsible for acute encephalitic syndrome (AES) in pediatric population in India. Several outbreaks of CHPV have been reported from different states of India since the year 2003. At present there is no vaccine or therapeutic measures available to curtail the disease. In this study, we have identified both T-cell and B-cell epitopes of different antigenic proteins of CHPV like Nucleoprotein (N), Phosphoprotein (P) and Matrix protein (M) along with the immuno-dominant glycoprotein (G) and conducted in silico characterization for the same. The idea is to design a multi-epitope peptide construct using the epitopes, which were found to be non-toxic, non-allergenic and possessing high immunogenicity. The final multi-epitope construct named as: MEC-CHPV, comprised of ß-defensin adjuvant at N-terminal for enhancement of immunogenicity followed by fourteen B-cell epitopes, four Helper T-cell epitopes and six Cytotoxic T-cell epitopes. The characterization of designed construct was carried out in terms of physicochemical parameters, antigenicity and allergenicity. The 3D structure prediction was performed. Molecular docking and molecular-dynamics simulation of MEC-CHPV with Toll like receptors (TLR-3 and TLR-8) showed stable interactions. In silico cloning of MEC-CHPV in pET30a(+) expression vector was also conducted using codon optimization. The in silico immune-simulation indicated a typical immune response against MEC-CHPV when used as a potential vaccine. This study provides a cost-effective and time-saving way to design a peptide vaccine candidate against CHPV using immuno-informatics approach. Development of the MEC-CHPV construct may pave the way for future laboratory experiments.Communicated by Ramaswamy H. Sarma.

Association of HLA alleles with hepatitis C infection in Maharashtra, western India.

BACKGROUND & OBJECTIVE: Host genetic diversity is believed to contribute to the spectrum of clinical outcomes in hepatitis C virus (HCV) infection. The present study aimed at finding out the frequencies of HLA class I and class II alleles of HCV infected individuals from western India. METHODS: Forty three clinically characterized anti-HCV positive patients from Maharashtra were studied for HLA A, B, C, DRB1 and DQB1 alleles by PCR- sequence specific primer (SSP) typing method and compared with 67 and 113 ethnically matched, anti-HCV negative healthy controls from western India. RESULTS: Our analysis revealed an association of HLA alleles HLA A*03 (OR= 16.69, EF, 0.44, P=7.9E-12), A*32 (OR= 1474, EF 0.21, P=1.8E-9), HLA B*15 (OR=14.11, EF 0.39, P=2.18E-10), B*55 (OR= 12.09, EF 0.07, P=0.005), Cw*16 (OR= 7.45, EF 0.12, P=0.001), Cw*18 (OR= 402, EF 0.05, P=0.003), DRB1*03 (OR= 4.01, EF 0.08, P=0.01) and DQB1*03 (OR= 3.02, EF 0.22, P=0.001), with HCV infection. HLA II locus haplotype DRB1*11-DQB1*03 (HF=17.64, OR=5.16, P=0.0001) was significantly increased among HCV infected individuals. INTERPRETATION & CONCLUSION: Our data suggest that among the western Indian population, certain HLA alleles or associated haplotype influence HCV infection as a host genetic factor.

Antibody and Memory B Cell Responses in Hepatitis E Recovered Individuals, 1-30 Years Post Hepatitis E Virus Infection.

Generation and persistence of anti-hepatitis E virus (HEV) antibodies are synonymous with the development of immunity and considered as correlates of protection against HEV infection. However, issues like longevity of immunological memory following recovery from hepatitis E still remains a puzzle. It is critical to understand whether anamnestic response exists for protection from HEV re-infection. The levels and persistence of anti-HEV antibodies were assessed in hepatitis E recovered individuals 1-30 years post HEV infection. The frequencies and functionality of recombinant HEV capsid protein (rORF2p)-stimulated memory B and T cells were also investigated 1-16 years post infection. Anti-HEV antibodies persisted in 91% of hepatitis E recovered individuals. HEV-specific memory B cell responses were detected in 95% of seropositive hepatitis E recovered individuals. CD4+ and CD8+ T cells displayed an effector memory cell phenotype in hepatitis E recovered individuals. In conclusion, long-lived anti-HEV antibodies and HEV-specific memory B cells are maintained for several years in hepatitis E recovered individuals. Involvement of CD4+ and CD8+ effector memory T cells is an important observation since it is inextricably linked to long-lasting protective immunity. In addition to anti-HEV antibodies, possible role of memory B cell response against HEV re-infection could also be considered.

Study of a hepatitis E virus outbreak involving drinking water and sewage contamination in Shimla, India, 2015-2016.

BACKGROUND: Hepatitis E, caused by hepatitis E virus (HEV), accounts for 50% of acute hepatitis cases in India. We report an outbreak of hepatitis E in Shimla, India, in 2015-2016. METHODS: ICMR-National Institute of Virology (NIV), Pune, received two batches of water samples from Shimla in January 2016 to test for the presence of enterically transmitted hepatitis viruses. Subsequently, 57 icterus patients were tested for various markers of hepatotropic viruses, i.e. anti-HEV IgM/IgG, anti-hepatitis A virus (anti-HAV) IgM/IgG antibodies and HEV RNA. Water samples were screened for HEV and HAV RNA followed by phylogenetic analysis. RESULTS: Overall, 48/57 patients availing municipal water had evidence of HEV infection, detected by serology and RT-PCR. All the water samples tested positive for HEV and HAV RNA, while the patients were negative for anti-HAV IgM antibody, indicating no recent HAV infection. Phylogenetic analysis confirmed the aetiological agent of the current outbreak to be HEV genotype 1. CONCLUSIONS: Serology and RT-PCR confirmed HEV as the aetiology of the outbreak. The absence of new cases of hepatitis A, despite the presence of HAV in the water supply, could be due to previously acquired immunity. Sewage contamination of water leading to faecal-oral transmission of HEV still remains a concern, thus emphasising the need for a vaccination/control strategy.

Differential inhibitory and activating NK cell receptor levels and NK/NKT-like cell functionality in chronic and recovered stages of chikungunya.

The role of natural killer (NK; CD3-CD56+)/NKT (CD3+CD56+)-like cells in chikungunya virus (CHIKV) disease progression/recovery remains unclear. Here, we investigated the expression profiles and function of NK and NKT-like cells from 35 chronic chikungunya patients, 30 recovered individuals, and 69 controls. Percentage of NKT-like cells was low in chronic chikungunya patients. NKp30+, CD244+, DNAM-1+, and NKG2D+ NK cell percentages were also lower (MFI and/or percentage), while those of CD94+ and NKG2A+ NKT-like cells were higher (MFI and/or percentage) in chronic patients than in recovered subjects. IFN-γ and TNF-α expression on NKT-like cells was high in the chronic patients, while only IFN-γ expression on NK cells was high in the recovered individuals. Furthermore, percentage of perforin+NK cells was low in the chronic patients. Lower cytotoxic activity was observed in the chronic patients than in the controls. CD107a expression on NK and NKT-like cells post anti-CD94/anti-NKG2A blocking was comparable among the patients and controls. Upregulated inhibitory and downregulated activating NK receptor expressions on NK/NKT-like cells, lower perforin+ and CD107a+NK cells are likely responsible for inhibiting the NK and NKT-like cell function in the chronic stage of chikungunya. Therefore, deregulation of NKR expression might underlie CHIKV-induced chronicity.