Manpreet Kaur

Autophagy is a lysosomal degradative pathway that has diverse physiological functions and plays crucial roles in several viral infections. Here we examine the role of autophagy in the life cycle of JEV, a neurotropic flavivirus. JEV infection leads to induction of autophagy in several cell types. JEV replication was significantly enhanced in neuronal cells where autophagy was rendered dysfunctional by ATG7 depletion, and in Atg5-deficient mouse embryonic fibroblasts (MEFs), resulting in higher viral titers. Autophagy was functional during early stages of infection however it becomes dysfunctional as infection progressed resulting in accumulation of misfolded proteins. Autophagy-deficient cells were highly susceptible to virus-induced cell death. We also observed JEV replication complexes that are marked by nonstructural protein 1 (NS1) and dsRNA colocalized with endogenous LC3 but not with GFP-LC3. Colocalization of NS1 and LC3 was also observed in Atg5 deficient MEFs, which contain only the nonlipidated form of LC3. Viral replication complexes furthermore show association with a marker of the ER-associated degradation (ERAD) pathway, EDEM1 (ER degradation enhancer, mannosidase α-like 1). Our data suggest that virus replication occurs on ERAD-derived EDEM1 and LC3-I-positive structures referred to as EDEMosomes. While silencing of ERAD regulators EDEM1 and SEL1L suppressed JEV replication, LC3 depletion exerted a profound inhibition with significantly reduced RNA levels and virus titers. Our study suggests that while autophagy is primarily antiviral for JEV and might have implications for disease progression and pathogenesis of JEV, nonlipidated LC3 plays an important autophagy independent function in the virus life cycle.

INTRODUCTION: mosquitoes are common vectors for dengue virus (DENV) and CHIK virus (CHIKV). In areas where both viruses cocirculate, they can be transmitted together. There are very few studies discussing the dengue-chik coinfection from Punjab region of India. The present study was undertaken to study the clinical features of dengue-CHIK coinfection and compare with monoinfection. MATERIALS AND METHODS: IgM antibody capture (MAC) ELISA for dengue IgM and CHIK IgM and ELISA for nonstructural protein 1 antigen was performed on serum samples obtained from suspected patients. RESULTS: Out of total 3160 samples from suspected patients for dengue infection, 2178 (68.92%) samples were positive for DENV while CHIK IgM antibodies were positive in 127 patients out of the total suspected 373 cases (34.04%). In addition to this, 283 samples were tested for both viruses, out of which 27 sera were positive (9.54%) for coinfection of dengue and CHIK. The comparison of signs and symptoms showed that the coinfected patients had fever in all cases while rash was seen in only 30% cases. Arthralgia (79%) and thrombocytopenia (77%) was seen in significant number of coinfected cases thus revealing overlapping nature of dengue-CHIK coinfection. CONCLUSION: Increase in the number of Dengue and Chikungunya infections and their cocirculation is an important public health concern which warrants the implementation of strict control measures.

The mechanisms underlying Japanese encephalitis virus (JEV) pathogenesis need to be thoroughly explored to delineate therapeutic approaches. It is believed that JEV manipulates the innate and adaptive compartments of the host's immune system to evade immune response and cross the blood-brain barrier. The present study was thus designed to investigate the functional modulation of DCs after exposure to JEV and to assess the consequences on CD4(+) T-lymphocyte functions. Human monocyte-derived DCs were either infected with 1 MOI of live virus, UV-inactivated virus, or were mock-infected. Replication-competent JEV induced a significant increase in the expression of maturation markers 48 h postinfection, along with that of programmed cell death 1 ligand 1 (PD-L1; also called B7-H1 and CD274). JEV-infected DCs expanded the Treg cells in allogenic mixed lymphocyte reactions. The expansion of Treg cells by JEV-infected DCs was significantly reduced upon blocking PD-L1 using an antagonist. In addition, JEV-infected DCs significantly altered the proliferation and reduced the polarization of Th cells toward the Th1-cell phenotype. The results, for the first time, suggest that JEV evades the host's immune system by modulating the crosstalk between DCs and T lymphocytes via the PD-L1 axis.