Japanese Encephalitis Virus Infected Human Monocyte-Derived Dendritic Cells Activate a Transcriptional Network Leading to an Antiviral Inflammatory Response

Abstract

A comprehensive understanding of the human immune response to virus infection is imperative for developing effective therapies, antivirals, and vaccines. Dendritic cells (DCs) are among the first cells to encounter the virus and are also key antigen-presenting cells that link the innate and adaptive immune system. In this study, we focus on the human immune response to the mosquito-borne Japanese encephalitis virus (JEV), which is the leading cause of virus-induced encephalitis in south-east Asia and has the potential to become a global pathogen. We describe the gene regulatory circuit of JEV infection in human monocyte-derived DCs (moDCs) along with its functional validation. We observe that JEV can productively infect human moDCs leading to robust transcriptional activation of the interferon and NF-κB-mediated antiviral and inflammatory pathways. This is accompanied with DC maturation and release of pro-inflammatory cytokines and chemokines TNFα, IL-6, IL-8, IL-12, MCP-1. and RANTES. JEV-infected moDCs activated T-regulatory cells (Tregs) in allogenic mixed lymphocyte reactions (MLR) as seen by upregulated FOXP3 mRNA expression, suggestive of a host response to reduce virus-induced immunopathology. The virus also downregulated transcripts involved in Peroxisome Proliferator Activated Receptor (PPAR) signalling and fatty acid metabolism pathways suggesting that changes in cellular metabolism play a crucial role in driving the DC maturation and antiviral responses. Collectively, our data describe and corroborate the human DC transcriptional network that is engaged upon JEV sensing.

Human Guanylate-Binding Protein 1 Positively Regulates Japanese Encephalitis Virus Replication in an Interferon Gamma Primed Environment

“…Robust activation of GBPs in response to JEV infection at both the transcript and protein levels has been shown in our previous studies on human monocyte derived dendritic cells and mouse embryonic fibroblasts ( Chauhan et al., 2021 ; Sharma et al., 2021a ). Here, we found that GBP1 expression was markedly induced in human epithelial HeLa cells upon JEV infection, and interestingly GBP1 strongly colocalized with JEV-NS1 protein that marks the virus replication complex.…”

“…A detailed understanding of the host-virus interaction is critical for the development of effective antivirals ( Turtle and Solomon, 2018 ; Sharma et al., 2021b ). While there are a few reports that have suggested the induction of various interferon-stimulated genes (ISGs) at both transcription and protein levels during JEV infection ( Yang et al., 2011 ; Zhang et al., 2013 ; Chauhan et al., 2021 ; Sharma et al., 2021a ), the finer details of the innate immune landscape during JEV infection remain largely unexplored.…”

Molecular pathogenesis of Japanese encephalitis and possible therapeutic strategies

“…The life cycle of JEV starts with the bite of a carrier mosquito, which releases virus particles that interact with receptors present on the surface of host cells, such as pericytes [ 98 ], fibroblasts [ 99 ], endothelial cells [ 100 – 102 ], dendritic cells [ 103 ], and myeloid cells [ 10 ], which are susceptible to JEV infection and are the primary sites of propagation of the virus. After replication in these cells, the newly assembled virion particles now migrate towards brain cells such as neuronal cells [ 104 ] and microglial cells [ 105 ] by using infected dendritic cells and T cells for their transport [ 98 ].…”

Japanese Encephalitis Virus: An Emerging Threat in the Indo-Pacific Region

“…Recently, the C protein crystal structure was revealed and it was shown to have αhelixes 1-4 secondary structure, which closely resembles with the capsid protein of DENV, WNV, and ZIKV [21]. Each monomer of the JEV capsid protein consists of four helices: α1 (amino acid [29][30][31][32][33][34][35][36][37][38], α2 (amino acid 44-57), α3 (amino acid [63][64][65][66][67][68][69][70], and the longest α4 (amino acid , connected by short loops. The amino-terminal of α helix-1 forms closed and open confirmation by which it tends to be flexible and allows possible antivirals against this domain.…”

“…The virus invades primarily innate immune cells in the skin like keratinocytes, Langerhans cells, fibroblasts, dermal dendritic cells and endothelial cells [35]. The dendritic cells are the primary target for JEV infection and potential the secretion of pro-inflammatory cytokines such as IL6, IL8, IL12 and TNF-α [36] and attracts other immune cells by which virus gets opportunity to enter the draining lymph nodes and secondary lymphoid organs like the spleen, followed by other peripheral tissues like the kidney, liver, heart, and lungs. The virus replicates in macrophages in tissues and monocytes in the blood [37].…”