Dengue is the most rapidly spreading viral disease transmitted by the bite of infected Aedes mosquitos. The pathogenesis of dengue is still unclear; although host immune responses and virus serotypes have been proposed to contribute to disease severity. In this study, we examined the circulating dengue virus (DENV) and measured plasma levels of inflammatory mediators. Ninety-eight patients during a dengue outbreak in eastern India in 2016 were included in the study. The presence of DENV was demonstrated by detecting NS1 antigen; IgM capture ELISA and serotypes were discriminated by type-specific RT-PCR and/or sequencing. Plasma samples were assayed for 41-plex cytokine/chemokines using multiplex Luminex assay. Eighty-five (87%) samples were positive by NS1/IgM capture ELISA/RT-PCR. All four serotypes of DENV were detected in this outbreak, with DENV-2 as the predominant type, seen in 55% of cases. Mixed infections were seen in 39% of subjects. Among the host inflammatory biomarkers, GM-CSF, IFN-γ, IL-10, IL-15, IL-8, MCP-1, IL-6, MIP-1β, and TNF-α levels were significantly increased in dengue with and without warning signs, in severe dengue patients in comparison to healthy controls. Four cytokines IFN-γ, GM-CSF, IL-10, and MIP-1β correlated significantly with disease severity and could serve as potential predictor for disease severity. Information on the host biomarkers and the dengue serotype may help guide in optimizing effective intervention strategies.

Background: Epidemiological evidence for decreased prevalence and/or mortality due to SARS-CoV-2 infections in countries endemic for malaria have been reported. However, such associational studies in human population are limited by known and several unknown confounding factors. The current study, the first of its kind, was designed to seek experimental evidence to test the hypothesis if prior exposure to Plasmodial infections cross-protect against SARS-CoV-2 challenge infection in a murine model, K-18 human ACE2 transgenic mice. Methods: Mice that had recovered from Plasmodium chabaudi infection 40 days earlier were challenged with a virulent strain of SARS-CoV-2 and viral load in lungs as well as mortality were scored and compared with K18 hACE2 mice that had not experienced prior malaria. Results: The viral load in lungs 6 days post challenge were comparable in malaria recovered mice and controls suggesting no significant generation of anti-viral immunity. However, mice with prior malaria exposure were significantly protected against SARS-CoV-2 induced mortality. Significant differences were observed in several host immune responses between the two groups when cytokines, chemokines and transcription factors were quantified in lungs. The plasma levels of several cytokines and chemokines were also significantly different between the two groups. Conclusion: The results of the study suggest that prior exposure to malaria protects mice against viral induced mortality in K18 hACE2 transgenic mice challenged with a virulent isolate of SARS- CoV-2 in the absence of demonstrable host immunity inhibiting viral growth in lungs.

Chitin, poly-N Acetyl D-glucosamine, is an abundant polysaccharide produced by fungal cell walls, insect epicuticle and nematodes cuticles. Its immunomodulatory function has curious attributes - paradoxically opposing host responses using different host receptors resulting in immunostimulatory or immunosuppressive propertis depending on the size/length of the oligomers as well as aceytylation levels have been reported in literature. Here we demonstrate that Hepta-N-Acetyl Chitoheptaose (7 mer) is a TLR2 ligand, 8 mer activates immune cells through TLR4 while, 6 mer is a relatively poor ligand for both TLR2 and TLR4 in generating inflammatory host cytokines. Significantly enhanced inflammatory response characterized by increased TNF-a, IL-1b, IL-6 and IL-10 was a feature of only 8 mer while, 6 and 7 mers induced modest activation in both HEK cells (transfected with specific TLRs) and in human THP2 cells in vitro. The translational significance of these features were addressed in an experimental model of Sepsis using Cecal Ligation Puncture (CLP) protocol, a murine model, considered a gold standard for human Sepsis. More significantly, therapeutic rather than prophylactic administration, that simulates real life scenerio of human and animal sepsis, of 7 mer rather than 6 or 8 residues of Chitin oligomer, significantly protected mice against sepsis as shown by decreased mortality and decreased induction of inflammatory cytokines. These findings suggest that modulation of immune response by chitopolysaccarides in-vivo is precisely caliberated.

Nematodes characteristically modulate effector immune responses by synthesizing and releasing both anti-inflammatory as well as proinflammatory molecules in infected hosts. Pre-clinical studies suggest that immuno-modulatory molecules and synthetic small molecules that mimic parasite products could have therapeutic value to ameliorate tissue damage found in inflammatory diseases. We report here identification of a glycoprotein from filarial parasite, a homologue of mammalian Heat Shock Protein 70 with immunostimulatory attributes. The purified native glycoprotein designated as FHSP70 and its recombinant protein moiety, WFL were found to be TLR2 and TLR4 agonists in vitro in human myeloid cells and induce systemic inflammatory cytokines in vivo. Cecal ligation and puncture (CLP) performed in mice which leads to onset of poly microbial sepsis and mortality could be treated by therapeutic administration of a single dose of FHSP70, along with antibiotics, suggesting its potential as a immunotherapeutic adjuvant for clinical management of Sepsis. Intra-nasal administration of WFL to mice followed by challenge with virulent human Influenza-A virus resulted in decreased viral growth as well as improved survival. The protective effect was demonstrable by both prophylactic as well as therapeutic intranasal administration of WFL. Further, therapeutic administration of WFL by intraperitoneal route 5 days post viral challenge also resulted in significant decrease in viral load in the respiratory tract. One sentence Summary Systemic administration of a Filarial HSP70 acts as an adjuvant therapy, through immuno-modulation, for improved survival against murine Polymicrobial Sepsis and Viral Infection while its intra nasal administration protects mice prophylactically as well as therapeutically against H1N1 Influenza viral challenge.