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Abstract In December 2023, we observed a notable shift in the COVID-19 landscape, when JN.1 omicron emerged as the predominant SARS-CoV-2 variant with a 95% incidence. We characterized the clinical profile, and genetic changes in JN.1, an emerging SARS-CoV-2 variant of interest. Whole genome sequencing was performed on SARS-CoV-2 positive clinical specimens, followed by sequence analysis. Mutations within the spike protein sequences were analysed and compared with the previously reported lineages and sub-lineages, to identify the potential impact of the unique mutations on protein structure and possible alterations in the functionality. Several unique and dynamic mutations were identified herein. Molecular docking analysis showed changes in the binding affinity, and key interacting residues of wild-type and mutated structures with key host cell receptors of SARS-CoV-2 entry viz., ACE2, CD147, CD209L and AXL. Our data provides key insights on the emergence of newer variants and highlights the necessity for robust and sustained global genomic surveillance of SARS-CoV-2.

Background: Chronic viral infection results in impaired immune responses rendering viral persistence. Here, we compared the quality of T-cell responses among chronic hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV)-infected individuals by examining the levels of expression of selected immune activation and exhaustion molecules on circulating MAIT cells and Tfh cells. Methods: Cytokines were measured using a commercial Bio-plex Pro Human Cytokine Grp I Panel 17-plex kit (BioRad, Hercules, CA, USA). Inflammation was assessed by measuring an array of plasma cytokines, and phenotypic alterations in CD4+ T cells including circulating Tfh cells, CD8+ T cells, and TCR iVα7.2+ MAIT cells in chronic HBV, HCV, and HIV-infected patients and healthy controls. The cells were characterized based on markers pertaining to immune activation (CD69, ICOS, and CD27) proliferation (Ki67), cytokine production (TNF-α, IFN-γ) and exhaustion (PD-1). The cytokine levels and T cell phenotypes together with cell markers were correlated with surrogate markers of disease progression. Results: The activation marker CD69 was significantly increased in CD4+hi T cells, while CD8+ MAIT cells producing IFN-γ were significantly increased in chronic HBV, HCV and HIV infections. Six cell phenotypes, viz., TNF-α+CD4+lo T cells, CD69+CD8+ T cells, CD69+CD4+ MAIT cells, PD-1+CD4+hi T cells, PD-1+CD8+ T cells, and Ki67+CD4+ MAIT cells, were independently associated with decelerating the plasma viral load (PVL). TNF-α levels showed a positive correlation with increase in cytokine levels and decrease in PVL. Conclusion: Chronic viral infection negatively impacts the quality of peripheral MAIT cells and Tfh cells via differential expression of both activating and inhibitory receptors.

In resource-limited settings, there is growing evidence that HIV testing is lacking among high-risk key populations such as men having sex with men, injection drug users, and transgenders largely due to stigma, discrimination, and lack of confidentiality. Findings from recent studies among high-risk key populations and the general population from various regions including resource-limited settings support the need for wider accessibility of HIV self-testing (HIV-ST) to reach those who may not otherwise have access to testing. Therefore, HIV-ST has untapped potential as a strategy to improve access to HIV testing and to increase testing frequency among key high-risk populations and their partners. Though HIV-ST has emerged as a safe, acceptable, and effective way to reach people, there are several roadblocks to implementing the HIV-ST policy, and fast-track policy implementation needs to be necessitated with newer or modified strategic plans.

Early detection of latent tuberculosis infection (LTBI) is critical to TB elimination in the current WHO vision of End Tuberculosis Strategy. The study investigates whether detecting plasma cytokines could aid in diagnosing LTBI across household contacts (HHCs) positive for IGRA, HHCs negative for IGRA, and healthy controls. The plasma cytokines were measured using a commercial Bio-Plex Pro Human Cytokine 17-plex assay. Increased plasma CXCL8 and decreased MCP-1, TNF-α, and IFN-γ were associated with LTBI. Regression analysis showed that a combination of CXCL8 and MCP-1 increased the risk of LTBI among HHCs to 14-fold. Our study suggests that CXCL-8 and MCP-1 could serve as the surrogate biomarkers of LTBI, particularly in resource-limited settings. Further laboratory investigations are warranted before extrapolating CXCL8 and MCP-1 for their usefulness as surrogate biomarkers of LTBI in resource-limited settings.

Chronic viral infections represent a leading cause of global morbidity and mortality. Chronic HBV, HCV, and HIV infections result in cytokine perturbations that may hold key implications in understanding the complex disease mechanisms driving virus persistence and/or resolution. Here, we determined the levels of various plasma cytokines using a commercial Bio-Plex Luminex cytokine array in chronic HBV (n = 30), HCV (n = 15), and HIV (n = 40) infections and correlated with corresponding plasma viral loads (PVLs) and liver parameters. We observed differential perturbations in cytokine profiles among the study groups. The cytokines levels positively correlated with PVL and liver transaminases. The monocyte-derived cytokines viz., MIP-1β, IL-8, and TNF-α, and Th2 cytokines like IL-4, IL-5, and IL-13 showed a better correlation with liver enzymes as compared to their corresponding PVLs. Our investigation also identified two cytokines viz., IL-5 and IL-7 that inversely correlated with HBV DNA and HIV PVLs, respectively. Regression analysis adjusted for age showed that every increase of IL-5 by one unit was associated with a reduction in HBV PVL by log10 0.4, whereas, every elevation by a unit of IL-7 was associated with decreased HIV PVL by log10 2.5. We also found that IL-7 levels correlated positively with absolute CD4+ T cell counts in HIV-infected patients. We concluded that plasma IL-5 and IL-7 may likely have a key role on viral control in HBV and HIV infections, respectively. A noteworthy increase in cytokines appears to bear protective and pathological significance, and indeed is reflective of the host’s versatile immune armory against viral persistence.

The rapid spread of SARS-CoV-2 variants in the global population is indicative of the development of selective advantages in emerging virus strains. Here, we performed a case-control investigation of the clinical and demographic characteristics, clinical history, and virological markers to predict disease progression in hospitalized adults for COVID-19 between December 2021 and January 2022 in Chennai, India. COVID-19 diagnosis was made by a commercial TaqPath COVID-19 RT-PCR, and WGS was performed with the Ion Torrent Next Generation Sequencing System. High-quality (

COVID-19 is being extensively studied, and much remains unknown regarding the long-term consequences of the disease on immune cells. The different arms of the immune system are interlinked, with humoral responses and the production of high-affinity antibodies being largely dependent on T cell immunity. Here, we longitudinally explored the effect COVID-19 has on T cell populations and the virus-specific T cells, as well as neutralizing antibody responses, for 6-7 months following hospitalization. The CD8+ TEMRA and exhausted CD57+ CD8+ T cells were markedly affected with elevated levels that lasted long into convalescence. Further, markers associated with T cell activation were upregulated at inclusion, and in the case of CD69+ CD4+ T cells this lasted all through the study duration. The levels of T cells expressing negative immune checkpoint molecules were increased in COVID-19 patients and sustained for a prolonged duration following recovery. Within 2-3 weeks after symptom onset, all COVID-19 patients developed anti-nucleocapsid IgG and spike-neutralizing IgG as well as SARS-CoV-2-specific T cell responses. In addition, we found alterations in follicular T helper (TFH) cell populations, such as enhanced TFH-TH2 following recovery from COVID-19. Our study revealed significant and long-term alterations in T cell populations and key events associated with COVID-19 pathogenesis.

HIV-1 infection gives rise to a multi-layered immune impairment in most infected individuals. The chronic presence of HIV-1 during the priming and activation of T cells by dendritic cells (DCs) promotes the expansion of suppressive T cells in a contact-dependent manner. The mechanism behind the T cell side of this HIV-induced impairment is well studied, whereas little is known about the reverse effects exerted on the DCs. Herein we assessed the phenotype and transcriptome profile of mature DCs that have been in contact with suppressive T cells. The HIV exposed DCs from cocultures between DCs and T cells resulted in a more tolerogenic phenotype with increased expression of e.g., PDL1, Gal-9, HVEM, and B7H3, mediated by interaction with T cells. Transcriptomic analysis of the DCs separated from the DC-T cell coculture revealed a type I IFN response profile as well as an activation of pathways involved in T cell exhaustion. Taken together, our data indicate that the prolonged and strong type I IFN signaling in DCs, induced by the presence of HIV during DC-T cell cross talk, could play an important role in the induction of tolerogenic DCs and suppressed immune responses seen in HIV-1 infected individuals.

The dynamics of host-virus interactions, and impairment of the host’s immune surveillance by dengue virus (DENV) serotypes largely remain ambiguous. Several experimental and preclinical studies have demonstrated how the virus brings about severe disease by activating immune cells and other key elements of the inflammatory cascade. Plasmablasts are activated during primary and secondary infections, and play a determinative role in severe dengue. The cross-reactivity of DENV immune responses with other flaviviruses can have implications both for cross-protection and severity of disease. The consequences of a cross-reactivity between DENV and anti-SARS-CoV-2 responses are highly relevant in endemic areas. Here, we review the latest progress in the understanding of dengue immunopathogenesis and provide suggestions to the development of target strategies against dengue.

BackgroundThe magnitude of protection conferred following recovery from COVID-19 or by vaccine administration, and the duration of protective immunity developed, remains ambiguous.MethodsWe investigated the factors associated with anti-SARS-CoV-2 S1 IgG decay in 519 individuals who recovered from COVID-19 illness or received COVID-19 vaccination with two commercial vaccines, viz., an adenoviral vector-based (AZD1222) and a whole-virion-based inactivated (BBV152) vaccine in Chennai, India from March to December 2021. Blood samples collected during regular follow-up post-infection/-vaccination were examined for anti-SARS-CoV-2 S1 IgG by a commercial automated chemiluminescent immunoassay (CLIA).ResultsAge and underlying comorbidities were the two variables that were independently associated with the development of a breakthrough infection. Individuals who were >60 years of age with underlying comorbid conditions (viz., hypertension, diabetes mellitus and cardiovascular disease) had a ~15 times and ~10 times greater odds for developing a breakthrough infection and hospitalization, respectively. The time elapsed since the first booster dose was associated with attrition in anti-SARS-CoV-2 IgG, where each month passed was associated with an ebb in the anti-SARS-CoV-2 IgG antibody levels by a coefficient of −6 units.ConclusionsOur findings advocate that the elderly with underlying comorbidities be administered with appropriate number of booster doses with AZD1222 and BBV152 against COVID-19.

In light of the COVID-19 pandemic, researchers across the world hastened to develop vaccines that would aid in bolstering herd immunity. Utilizing mRNA coding and viral vector technology, the currently approved vaccines were required to undergo extensive testing to confirm their safety for mass usage in the general population. However, clinical trials failed to test the safety and efficacy of the COVID-19 vaccines in groups with weakened immune systems, especially pregnant women. Lack of information on the effects of vaccinations in pregnancy and the safety of fetuses are among the topmost reasons preventing pregnant women from receiving immunization. Thus, the lack of data examining the effects of COVID-19 vaccinations on pregnant women must be addressed. This review focused on the safety and efficacy of the approved COVID-19 vaccinations in pregnancy and their impact on both maternal and fetal immune responses. For that, we took the approach of combined systematic review/meta-analysis and compiled the available data from the original literature from PubMed, Web of Science, EMBASE and Medline databases. All articles analyzed presented no adverse effects of vaccination in pregnancy, with varying conclusions on the degree of effectiveness. The majority of the findings described robust immune responses in vaccinated pregnant women, successful transplacental antibody transfer, and implications for neonatal immunity. Hence, findings from the cumulative data available can be helpful in achieving COVID-19 herd immunization, including pregnant women.

The lethal combination involving TB and HIV, known as “syndemic” diseases, synergistically act upon one another to magnify the disease burden. Individuals on anti-retroviral therapy (ART) are at risk of developing TB-associated immune reconstitution inflammatory syndrome (TB-IRIS). The underlying inflammatory complication includes the rapid restoration of immune responses following ART, eventually leading to exaggerated inflammatory responses to MTB antigens. TB-IRIS continues to be a cause of morbidity and mortality among HIV/TB coinfected patients initiating ART, and although a significant quantum of knowledge has been acquired on the pathogenesis of IRIS, the underlying pathomechanisms and identification of a sensitive and specific diagnostic marker still remain a grey area of investigation. Here, we reviewed the latest research developments into IRIS immunopathogenesis, and outlined the modalities to prevent and manage strategies for better clinical and diagnostic outcomes for IRIS.

Burkholderia pseudomallei (B. pseudomallei) causes melioidosis, a potentially fatal disease for which no licensed vaccine is available thus far. The host-pathogen interactions in B. pseudomallei infection largely remain the tip of the iceberg. The pathological manifestations are protean ranging from acute to chronic involving one or more visceral organs leading to septic shock, especially in individuals with underlying conditions similar to COVID-19. Pathogenesis is attributed to the intracellular ability of the bacterium to ‘step into’ the host cell’s cytoplasm from the endocytotic vacuole, where it appears to polymerize actin filaments to spread across cells in the closer vicinity. B. pseudomallei effectively evades the host’s surveillance armory to remain latent for prolonged duration also causing relapses despite antimicrobial therapy. Therefore, eradication of intracellular B. pseudomallei is highly dependent on robust cellular immune responses. However, it remains ambiguous why certain individuals in endemic areas experience asymptomatic seroconversion, whereas others succumb to sepsis-associated sequelae. Here, we propose key insights on how the host’s surveillance radars get commandeered by B. pseudomallei.

Genital mucosal transmission is the most common route of HIV spread. The initial responses triggered at the site of viral entry are reportedly affected by host factors, especially complement components present at the site, and this will have profound consequences on the outcome and pathogenesis of HIV infection. We studied the initial events associated with host-pathogen interactions by exposing cervical biopsies to free or complement-opsonized HIV. Opsonization resulted in higher rates of HIV acquisition/infection in mucosal tissues and emigrating dendritic cells. Transcriptomic and proteomic data showed a significantly more pathways and higher expression of genes and proteins associated with viral replication and pathways involved in different aspects of viral infection including interferon signaling, cytokine profile and dendritic cell maturation for the opsonized HIV. Moreover, the proteomics data indicate a general suppression by the HIV exposure. This clearly suggests that HIV opsonization alters the initial signaling pathways in the cervical mucosa in a manner that promotes viral establishment and infection. Our findings provide a foundation for further studies of the role these early HIV induced events play in HIV pathogenesis.

Gut microbiome alterations may play a paramount role in determining the clinical outcome of clinical COVID-19 with underlying comorbid conditions like T2D, cardiovascular disorders, obesity, etc. Research is warranted to manipulate the profile of gut microbiota in COVID-19 by employing combinatorial approaches such as the use of prebiotics, probiotics and symbiotics. Prediction of gut microbiome alterations in SARS-CoV-2 infection may likely permit the development of effective therapeutic strategies. Novel and targeted interventions by manipulating gut microbiota indeed represent a promising therapeutic approach against COVID-19 immunopathogenesis and associated co-morbidities. The impact of SARS-CoV-2 on host innate immune responses associated with gut microbiome profiling is likely to contribute to the development of key strategies for application and has seldom been attempted, especially in the context of symptomatic as well as asymptomatic COVID-19 disease.

HIV transmission via genital and colorectal mucosa are the most common routes of dissemination. Here, we explored the effects of free and complement-opsonized HIV on colorectal tissue. Initially, there was higher antiviral responses in the free HIV compared to complement-opsonized virus. The mucosal transcriptional response at 24 hr revealed the involvement of activated T cells, which was mirrored in cellular responses observed at 96 hr in isolated mucosal T cells. Further, HIV exposure led to skewing of T cell phenotypes predominantly to inflammatory CD4+ T cells, that is Th17 and Th1Th17 subsets. Of note, HIV exposure created an environment that altered the CD8+ T cell phenotype, for example expression of regulatory factors, especially when the virions were opsonized with complement factors. Our findings suggest that HIV-opsonization alters the activation and signaling pathways in the colorectal mucosa, which promotes viral establishment by creating an environment that stimulates mucosal T cell activation and inflammatory Th cells.

Tuberculosis (TB) treatment monitoring is paramount to clinical decision-making and the host biomarkers appears to play a significant role. The currently available diagnostic technology for TB detection is inadequate. Although GeneXpert detects total DNA present in the sample regardless live or dead bacilli present in clinical samples, all the commercial tests available thus far have low sensitivity. Humoral responses against Mycobacterium tuberculosis (Mtb) antigens are generally low, which precludes the use of serological tests for TB diagnosis, prognosis, and treatment monitoring. Mtb-specific CD4+ T cells correlate with Mtb antigen/bacilli burden and hence might serve as good biomarkers for monitoring treatment progress. Omics-based techniques are capable of providing a more holistic picture for disease mechanisms and are more accurate in predicting TB disease outcomes. The current review aims to discuss some of the recent advances on TB biomarkers, particularly host biomarkers that have the potential to diagnose and differentiate active TB and LTBI as well as their use in disease prognosis and treatment monitoring.

Genital herpes is a common sexually transmitted infection caused by herpes simplex virus type 2 (HSV-2). Genital herpes significantly enhances the acquisition and transmission of HIV-1 by creating a microenvironment that supports HIV infection in the host. Dendritic cells (DCs) represent one of the first innate cell types that encounter HIV-1 and HSV-2 in the genital mucosa. HSV-2 infection has been shown to modulate DCs, rendering them more receptive to HIV infection. Here, we investigated the potential mechanisms underlying HSV-2-mediated augmentation of HIV-1 infection. We demonstrated that the presence of HSV-2 enhanced productive HIV-1 infection of DCs and boosted inflammatory and antiviral responses. The HSV-2 augmented HIV-1 infection required intact HSV-2 DNA, but not active HSV-2 DNA replication. Furthermore, the augmented HIV infection of DCs involved the cGAS-STING pathway. Interestingly, we could not see any involvement of TLR2 or TLR3 nor suppression of infection by IFN-β production. The conditioning by HSV-2 in dual exposed DCs decreased protein expression of IFI16, cGAS, STING, and TBK1, which is associated with signaling through the STING pathway. Dual exposure to HSV-2 and HIV-1 gave decreased levels of several HIV-1 restriction factors, especially SAMHD1, TREX1, and APOBEC3G. Activation of the STING pathway in DCs by exposure to both HSV-2 and HIV-1 most likely led to the proteolytic degradation of the HIV-1 restriction factors SAMHD1, TREX1, and APOBEC3G, which should release their normal restriction of HIV infection in DCs. This released their normal restriction of HIV infection in DCs. We showed that HSV-2 reprogramming of cellular signaling pathways and protein expression levels in the DCs provided a setting where HIV-1 can establish a higher productive infection in the DCs. In conclusion, HSV-2 reprogramming opens up DCs for HIV-1 infection and creates a microenvironment favoring HIV-1 transmission.

Abstract Background Currently, several assays can diagnose acute dengue infection. However, none of these assays can predict the severity of the disease. Biomarkers that predicts the likelihood that a dengue patient will develop a severe form of the disease could permit more efficient patient triage and allows better supportive care for the individual in need, especially during dengue outbreaks. Methods We measured 20 plasma markers i.e. IFN-γ, IL-10, granzyme-B, CX3CL1, IP-10, RANTES, CXCL8, CXCL6, VCAM, ICAM, VEGF, HGF, sCD25, IL-18, LBP, sCD14, sCD163, MIF, MCP-1 and MIP-1β in 141 dengue patients in over 230 specimens and correlate the levels of these plasma markers with the development of dengue without warning signs (DWS−), dengue with warning signs (DWS+) and severe dengue (SD). Results Our results show that the elevation of plasma levels of IL-18 at both febrile and defervescence phase was significantly associated with DWS+ and SD; whilst increase of sCD14 and LBP at febrile phase were associated with severity of dengue disease. By using receiver operating characteristic (ROC) analysis, the IL-18, LBP and sCD14 were significantly predicted the development of more severe form of dengue disease (DWS+/SD) (AUC = 0.768, P

Gut microbiota refers to a complex network of microbes, which exerts a marked influence on the host’s health. It is composed of bacteria, fungi, viruses, and helminths. Bacteria, or collectively, the bacteriome, comprises a significant proportion of the well-characterized microbiome. However, the other communities referred to as ‘dark matter’ of microbiomes such as viruses (virome), fungi (mycobiome), archaea (archaeome), and helminths have not been completely elucidated. Development of new and improved metagenomics methods has allowed the identification of complete genomes from the genetic material in the human gut, opening new perspectives on the understanding of the gut microbiome composition, their importance, and potential clinical applications. Here, we review the recent evidence on the viruses, fungi, archaea, and helminths found in the mammalian gut, detailing their interactions with the resident bacterial microbiota and the host, to explore the potential impact of the microbiome on host’s health. The role of fecal virome transplantations, pre-, pro-, and syn-biotic interventions in modulating the microbiome and their related concerns are also discussed.

Dendritic cells (DCs), natural killer (NK) cells, and T cells play critical roles during primary HIV-1 exposure at the mucosa, where the viral particles become coated with complement fragments and mucosa-associated antibodies. The microenvironment together with subsequent interactions between these cells and HIV at the mucosal site of infection will determine the quality of immune response that ensues adaptive activation. Here, we investigated how complement and immunoglobulin opsonization influences the responses triggered in DCs and NK cells, how this affects their cross talk, and what T cell phenotypes are induced to expand following the interaction. Our results showed that DCs exposed to complement-opsonized HIV (C-HIV) were less mature and had a poor ability to trigger IFN-driven NK cell activation. In addition, when the DCs were exposed to C-HIV, the cytotolytic potentials of both NK cells and CD8 T cells were markedly suppressed. The expression of PD-1 as well as co-expression of negative immune checkpoints TIM-3 and LAG-3 on PD-1 positive cells were increased on both CD4 as well as CD8 T cells upon interaction with and priming by NK–DC cross talk cultures exposed to C-HIV. In addition, stimulation by NK–DC cross talk cultures exposed to C-HIV led to the upregulation of CD38, CXCR3, and CCR4 on T cells. Together, the immune modulation induced during the presence of complement on viral surfaces is likely to favor HIV establishment, dissemination, and viral pathogenesis.

Mucosal-associated invariant T (MAIT) cells, defined as CD161++TCR iVα7.2+ T cells, play an important role in the innate defense against bacterial infections, and their functionality is impaired in chronic viral infections. Here, we investigated the frequency and functional role of MAIT cells in chronic hepatitis B virus (HBV) infection. The peripheral CD3+CD161++TCR iVα7.2+ MAIT cells in chronic HBV-infected patients and healthy controls were phenotypically characterized based on CD57, PD-1, TIM-3, and CTLA-4, as well as HLA-DR and CD38 expression. The frequency of MAIT cells was significantly decreased among chronic HBV-infected individuals as compared to controls. Expression of CD57, PD-1, CTLA-4, as well as HLA-DR and CD38 on MAIT cells was significantly elevated in chronic HBV-infected individuals relative to controls. The percentage of T cell receptor (TCR) iVα7.2+ CD161+ MAIT cells did not correlate with HBV viral load but inversely with HLA-DR on CD4+ T cells and MAIT cells and with CD57 on CD8+ T cells suggesting that decrease of MAIT cells may not be attributed to direct infection by HBV but driven by HBV-induced chronic immune activation. The percentage and expression levels of PD-1 as well as CTLA-4 on MAIT cells inversely correlated with plasma HBV-DNA levels, which may suggest either a role for MAIT cells in the control of HBV infection or the effect of HBV replication in the liver on MAIT cell phenotype. We report that decrease of TCR iVα7.2+ MAIT cells in the peripheral blood and their functions were seemingly impaired in chronic HBV-infected patients likely because of the increased expression of PD-1.

Melioidosis is a neglected tropical disease endemic across South East Asia and Northern Australia. The etiological agent, Burkholderia pseudomallei (B.pseudomallei), is a Gram-negative, rod-shaped, motile bacterium residing in the soil and muddy water across endemic regions of the tropical world. The bacterium is known to cause persistent infections by remaining latent within host cells for prolonged duration. Reactivation of the recrudescent disease often occurs in elders whose immunity wanes. Moreover, recurrence rates in melioidosis patients can be up to ~13% despite appropriate antibiotic therapy, suggestive of bacterial persistence and inefficacy of antibiotic regimens. The mechanisms behind bacterial persistence in the host remain unclear, and hence understanding host immunity during persistent B. pseudomallei infections may help designing potential immunotherapy.A persistent infection was generated using a small-colony variant (SCV) and a wild-type (WT) B. pseudomallei in BALB/c mice via intranasal administration. Infected mice that survived for >60 days were sacrificed. Lungs, livers, spleens, and peripheral blood mononuclear cells were harvested for experimental investigations. Histopathological changes of organs were observed in the infected mice, suggestive of successful establishment of persistent infections. Moreover, natural killer (NK) cell frequency was increased in SCV- and WT-infected mice. We observed programmed death-1 (PD-1) upregulation on B cells of SCV- and WT-infected mice. Interestingly, PD-1 upregulation was only observed on NK cells and monocytes of SCV-infected mice. In contrast, cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) downregulation was seen on NK cells of WT-infected mice, and on monocytes of SCV- and WT-infected mice.The SCV and the WT of B. pseudomallei distinctly upregulated PD-1 expression on B cells, NK cells, and monocytes to dampen host immunity, which likely facilitates bacterial persistence. PD-1/PD-L1 pathway appears to play an important role in the persistence of B. pseudomallei in the host.

BACKGROUND:During infection, successful bacterial clearance is achieved via the host immune system acting in conjunction with appropriate antibiotic therapy. However, it still remains a tip of the iceberg as to where persistent pathogens namely, Burkholderia pseudomallei (B. pseudomallei) reside/hide to escape from host immune sensors and antimicrobial pressure. METHODS:We used transmission electron microscopy (TEM) to investigate post-mortem tissue sections of patients with clinical melioidosis to identify the localisation of a recently identified gut microbiome, B. pseudomallei within host cells. The intranuclear presence of B. pseudomallei was confirmed using transmission electron microscopy (TEM) of experimentally infected guinea pig spleen tissues and Live Z-stack, and ImageJ analysis of fluorescence microscopy analysis of in vitro infection of A549 human lung epithelial cells. RESULTS:TEM investigations revealed intranuclear localization of B. pseudomallei in cells of infected human lung and guinea pig spleen tissues. We also found that B. pseudomallei induced actin polymerization following infection of A549 human lung epithelial cells. Infected A549 lung epithelial cells using 3D-Laser scanning confocal microscopy (LSCM) and immunofluorescence microscopy confirmed the intranuclear localization of B. pseudomallei. CONCLUSION:B. pseudomallei was found within the nuclear compartment of host cells. The nucleus may play a role as an occult or transient niche for persistence of intracellular pathogens, potentially leading to recurrrent episodes or recrudescence of infection.

BACKGROUND:Burkholderia pseudomallei, the causative agent of melioidosis poses a serious threat to humankind. B. pseudomallei secretes numerous virulence proteins that alter host cell functions to escape from intracellular immune sensors. However, the events underlying disease pathogenesis are poorly understood. METHODS:We determined the ability of B. pseudomallei to invade and survive intracellularly in A549 human lung epithelial cells, and also investigated the early transcriptional responses using an Illumina HumanHT-12 v4 microarray platform, after three hours of exposure to live B. pseudomallei (BCMS) and its secreted proteins (CCMS). RESULTS:We found that the ability of B. pseudomallei to invade and survive intracellularly correlated with increase of multiplicity of infection and duration of contact. Activation of host carbohydrate metabolism and apoptosis as well as suppression of amino acid metabolism and innate immune responses both by live bacteria and its secreted proteins were evident. These early events might be linked to initial activation of host genes directed towards bacterial dissemination from lungs to target organs (via proposed in vivo mechanisms) or to escape potential sensing by macrophages. CONCLUSION:Understanding the early responses of A549 cells toward B. pseudomallei infection provide preliminary insights into the likely pathogenesis mechanisms underlying melioidosis, and could contribute to development of novel intervention strategies to combat B. pseudomallei infections.

Burkholderia pseudomallei (B. pseudomallei), the causative agent of melioidosis, is a deadly pathogen endemic across parts of tropical South East Asia and Northern Australia. B. pseudomallei can remain latent within the intracellular compartment of the host cell over prolonged periods of time, and cause persistent disease leading to treatment difficulties. Understanding the immunological mechanisms behind persistent infection can result in improved treatment strategies in clinical melioidosis.Ten-day LD50 was determined for the small-colony variant (SCV) and its parental wild-type (WT) via intranasal route in experimental BALB/c mice. Persistent B. pseudomallei infection was generated by administrating sub-lethal dose of the two strains based on previously determined LD50. After two months, peripheral blood mononuclear cells (PBMCs) and plasma were obtained to investigate host immune responses against persistent B. pseudomallei infection. Lungs, livers, and spleens were harvested and bacterial loads in these organs were determined.Based on the ten-day LD50, the SCV was ~20-fold less virulent than the WT. The SCV caused higher bacterial loads in spleens compared to its WT counterparts with persistent B. pseudomallei infection. We found that the CD4+ T-cell frequencies were decreased, and the expressions of PD-1, but not CTLA-4 were significantly increased on the CD4+ and CD8+ T cells of these mice. Notably, persistent infection with the SCV led to significantly higher levels of PD-1 than the WT B. pseudomallei. Plasma IFN-γ, IL-6, and IL-17A levels were elevated only in SCV-infected mice. In addition, skewed plasma Th1 and Th17 responses were observed in SCV-infected mice relative to WT-infected and uninfected mice.B. pseudomallei appears to upregulate the expression of PD-1 on T cells to evade host immune responses, which likely facilitates bacterial persistence in the host. SCVs cause distinct pathology and immune responses in the host as compared to WT B. pseudomallei.

Fungal infections (mycoses) are likely to occur more frequently as ever-increasingly sophisticated healthcare systems create greater risk factors. There is a paucity of systematic data on the incidence and prevalence of human fungal infections in Malaysia. We conducted a comprehensive study to estimate the burden of serious fungal infections in Malaysia. Our study showed that recurrent vaginal candidiasis (>4 episodes/year) was the most common of all cases with a diagnosis of candidiasis (n = 501,138). Oesophageal candidiasis (n = 5850) was most predominant among individuals with HIV infection. Candidemia incidence (n = 1533) was estimated in hospitalized individuals, some receiving treatment for cancer (n = 1073), and was detected also in individuals admitted to intensive care units (ICU) (n = 460). In adults with asthma, allergic bronchopulmonary aspergillosis (ABPA) was the second most common respiratory mycoses noticed (n = 30,062) along with severe asthma with fungal sensitization (n = 39,628). Invasive aspergillosis was estimated in 184 cases undergoing anti-cancer treatment and 834 ICU cases. Cryptococcal meningitis was diagnosed in 700 subjects with HIV/AIDS and Pneumocystis jirovecii pneumonitis (PCP) in 1286 subjects with underlying HIV disease. The present study indicates that at least 590,214 of the Malaysian population (1.93%) is affected by a serious fungal infection annually. This problem is serious enough to warrant the further epidemiological studies to estimate the burden of human fungal infections in Malaysia.

Lack of vaccine and effective antiviral drugs against chikungunya virus (CHIKV) outbreaks have led to significant impact on health care in the developing world. Here, we evaluated the antiviral effects of tetracycline (TETRA) derivatives and other common antiviral agents against CHIKV. Our results showed that within the TETRA derivatives group, Doxycycline (DOXY) exhibited the highest inhibitory effect against CHIKV replication in Vero cells. On the other hand, in the antiviral group Ribavirin (RIBA) showed higher inhibitory effects against CHIKV replication compared to Aciclovir (ACIC). Interestingly, RIBA inhibitory effects were also higher than all but DOXY within the TETRA derivatives group. Docking studies of DOXY to viral cysteine protease and E2 envelope protein showed non-competitive interaction with docking energy of -6.6±0.1 and -6.4±0.1 kcal/mol respectively. The 50% effective concentration (EC50) of DOXY and RIBA was determined to be 10.95±2.12 μM and 15.51±1.62 μM respectively, while DOXY+RIBA (1:1 combination) showed an EC50 of 4.52±1.42 μM. When compared, DOXY showed higher inhibition of viral infectivity and entry than RIBA. In contrast however, RIBA showed higher inhibition against viral replication in target cells compared to DOXY. Assays using mice as animal models revealed that DOXY+RIBA effectively inhibited CHIKV replication and attenuated its infectivity in vivo. Further experimental and clinical studies are warranted to investigate their potential application for clinical intervention of CHIKV disease.

Mucosal-associated invariant T (MAIT) cells are evolutionarily conserved antimicrobial MR1-restricted CD8(+) T cells co-expressing the semi-invariant TCR Vα7.2, and are numerous in the blood and mucosal tissues of humans. MAIT cells appear to undergo exhaustion in chronic viral infections. However, their role in human immunodeficiency virus type 1 (HIV-1) mono-infection and HIV/tuberculosis (TB) co-infection have seldom been elaborately investigated. We conducted a cross-sectional study to investigate the frequencies and phenotypes of CD161(++)CD8(+) T cells among anti-retroviral therapy (ART)/anti-TB therapy (ATT) treatment-naïve HIV/TB co-infected, ART/TB treated HIV/TB co-infected, ART naïve HIV-infected, ART-treated HIV-infected patients, and HIV negative healthy controls (HCs) by flow cytometry. Our data revealed that the frequency of MAIT cells was severely depleted in HIV mono- and HIV/TB co-infections. Further, PD-1 expression on MAIT cells was significantly increased in HIV mono- and HIV-TB co-infected patients. The frequency of MAIT cells did not show any significant increase despite the initiation of ART and/or ATT. Majority of the MAIT cells in HCs showed a significant increase in CCR6 expression as compared to HIV/TB co-infections. No marked difference was seen with expressions of chemokine co-receptor CCR5 and CD103 among the study groups. Decrease of CCR6 expression appears to explain why HIV-infected patients display weakened mucosal immune responses.

Helicobacter pylori (H. pylori) -induced gastric inflammation impacts the functions of leptin- and ghrelin-producing cells in the gastroduodenum. Inflammation resulting from H. pylori sensing via Toll-like receptors (TLRs) and the associated downstream signaling largely remain ambiguous. Here, we investigated the role of gut hormones, pro-inflammatory cytokines and single nucleotide polymorphisms (SNPs) associated with TLR 4p14 in H. pylori disease in 30 subjects with non-ulcer dyspepsia (NUD), 40 with peptic ulcer disease (PUD) and 15 with gastric cancer (GC) subjects positive and negative for H. pylori infection. The level of pro-inflammatory cytokines was directly proportional to the severity of gastritis, and disease status influenced the levels of gut hormones and pro-inflammatory cytokines. TLR-1 SNPs rs4833095 and TLR-10 SNPs rs10004195 and were directly associated with H. pylori disease, and were up-regulated in the presence of H. pylori in a genotype-independent manner. We concluded that TLR-1 rs4833095 and TLR10 rs10004195 confer susceptibility to development of gastroduodenal disease, especially GC in H.pylori disease.

OBJECTIVES: Dengue represents one of the most serious life-threatening vector-borne infectious diseases that afflicts approximately 50 million people across the globe annually. Whilst symptomatic infections are frequently reported, asymptomatic dengue remains largely unnoticed. Therefore, we sought to investigate the immune correlates conferring protection to individuals that remain clinically asymptomatic. METHODS: We determined the levels of neutralizing antibodies (nAbs) and gene expression profiles of host immune factors in individuals with asymptomatic infections, and whose cognate household members showed symptoms consistent to clinical dengue infection. RESULTS: We observed broad down-regulation of host defense response (innate, adaptive and matrix metalloprotease) genes in asymptomatic individuals as against symptomatic patients, with selective up-regulation of distinct genes that have been associated with protection. Selected down-regulated genes include: TNF α (TNF), IL8, C1S, factor B (CFB), IL2, IL3, IL4, IL5, IL8, IL9, IL10 and IL13, CD80, CD28, and IL18, MMP8, MMP10, MMP12, MMP15, MMP16, and MMP24. Selected up-regulated genes include: RANTES (CCL5), MIP-1α (CCL3L1/CCL3L3), MIP-1β (CCL4L1), TGFβ (TGFB), and TIMP1. CONCLUSION: Our findings highlight the potential association of certain host genes conferring protection against clinical dengue. These data are valuable to better explore the mysteries behind the hitherto poorly understood immunopathogenesis of subclinical dengue infection.

Oxalate toxicity is mediated through generation of reactive oxygen species (ROS) via a process that is partly dependent on mitochondrial dysfunction. Here, we investigated whether C-phycocyanin (CP) could protect against oxidative stress-mediated intracellular damage triggered by oxalate in MDCK cells. DCFDA, a fluorescence-based probe and hexanoyl-lysine adduct (HEL), an oxidative stress marker were used to investigate the effect of CP on oxalate-induced ROS production and membrane lipid peroxidation (LPO). The role of CP against oxalate-induced oxidative stress was studied by the evaluation of mitochondrial membrane potential by JC1 fluorescein staining, quantification of ATP synthesis and stress-induced MAP kinases (JNK/SAPK and ERK1/2). Our results revealed that oxalate-induced cells show markedly increased ROS levels and HEL protein expression that were significantly decreased following pre-treatment with CP. Further, JC1 staining showed that CP pre-treatment conferred significant protection from mitochondrial membrane permeability and increased ATP production in CP-treated cells than oxalate-alone-treated cells. In addition, CP treated cells significantly decreased the expression of phosphorylated JNK/SAPK and ERK1/2 as compared to oxalate-alone-treated cells. We concluded that CP could be used as a potential free radical-scavenging therapeutic strategy against oxidative stress-associated diseases including urolithiasis.

Abdominal aortic aneurysm (AAA) is a common chronic degenerative disease characterized by progressive aortic dilation and rupture. The mechanisms underlying the role of α-tocopherol and β-carotene on AAA have not been comprehensively assessed. We investigated if α-tocopherol and β-carotene supplementation could attenuate AAA, and studied the underlying mechanisms utilized by the antioxidants to alleviate AAA. Four-months-old Apoe(-/-) mice were used in the induction of aneurysm by infusion of angiotensin II (Ang II), and were orally administered with α-tocopherol and β-carotene enriched diet for 60 days. Significant increase of LDL, cholesterol, triglycerides and circulating inflammatory cells was observed in the Ang II-treated animals, and gene expression studies showed that ICAM-1, VCAM-1, MCP-1, M-CSF, MMP-2, MMP-9 and MMP-12 were upregulated in the aorta of aneurysm-induced mice. Extensive plaques, aneurysm and diffusion of inflammatory cells into the tunica intima were also noticed. The size of aorta was significantly (P = 0.0002) increased (2.24±0.20 mm) in the aneurysm-induced animals as compared to control mice (1.17±0.06 mm). Interestingly, β-carotene dramatically controlled the diffusion of macrophages into the aortic tunica intima, and circulation. It also dissolved the formation of atheromatous plaque. Further, β-carotene significantly decreased the aortic diameter (1.33±0.12 mm) in the aneurysm-induced mice (β-carotene, P = 0.0002). It also downregulated ICAM-1, VCAM-1, MCP-1, M-CSF, MMP-2, MMP-9, MMP-12, PPAR-α and PPAR-γ following treatment. Hence, dietary supplementation of β-carotene may have a protective function against Ang II-induced AAA by ameliorating macrophage recruitment in Apoe(-/-) mice.