Priyanshu Srivastava

Establishment of a viral infection in the host involves complex interactions between the virus and the host. The present study was undertaken to evaluate one such interaction between a host microRNA (miRNA) with both the virus and its cellular target. Through a comprehensive high-throughput screen of a human miRNA mimics library, we identified that hsa-miR-122b-5p bound to chikungunya virus (CHIKV) 3′-untranslated region (3′-UTR), which we abrogated upon mutating the binding sites of the miRNA and determined that this miRNA regulated CHIKV infection. In-depth scrutiny of this miRNA’s expression in CHIKV-susceptible host cells divulged that it was mainly expressed in macrophages, and temporal expression profiling analysis in these cells revealed that its expression negatively correlated to the virus infection. We further identified cellular targets of miR-122b-5p through global RNA seq analysis using antagomiRs, among which histone deacetylase 4 (HDAC4) displayed attributes that promoted CHIKV infection in macrophages. To dissect this phenomenon further, we performed loss-of-function assays using both miR-122b-5p and HDAC4 and observed regulation of pro-inflammatory cytokines, including the type I interferon system. Furthermore, miRNA mimics and antagomiR assays indicated that regulation of HDAC4 by miR-122b-5p may be associated with changes in the nuclear translocation of phosphorylated IRF3 during CHIKV infection. While this suggests a possible link, additional studies are needed to confirm this interaction and its underlying mechanism. Taken altogether, our study provides insights into the dual regulatory function of miR-122b-5p during CHIKV infection, highlighting its capacity to decrease viral titer by binding directly to the 3′UTR of the viral genome and its potential to promote nuclear translocation of phosphorylated IRF3, which may be indirectly influenced by modulation of its cellular target, HDAC4, thereby regulating host immune responses during CHIKV infection in macrophages. These findings may have significant implications for understanding the pathogenesis of CHIKV and for developing novel therapeutic strategies. IMPORTANCE: Human microRNAs (miRNAs) are central regulators of viral infection, acting through direct targeting of viral genomes or by modulating host cellular pathways. In this study, we demonstrate that miR-122b-5p plays a dual antiviral role during chikungunya virus (CHIKV) infection in macrophages—critical immune cells that serve as viral reservoirs. We show that miR-122b-5p directly binds to the 3′ untranslated region of the CHIKV genome, thereby suppressing viral replication. Additionally, we uncover a previously uncharacterized mechanism in which miR-122b-5p modulates the host innate immune response by repressing HDAC4, a negative regulator of the type I interferon pathway. This repression may influence nuclear translocation of phosphorylated IRF3, potentially enhancing the antiviral transcriptional response. Our findings not only deepen our understanding of macrophage-intrinsic antiviral defenses against CHIKV but also highlight miR-122b-5p as a potential therapeutic target for enhancing host immunity and limiting viral propagation.

Chikungunya virus (CHIKV), a mosquito-borne alphavirus, has re-emerged, causing widespread outbreaks and a significant clinical burden. Despite advances in virology, the molecular mechanisms governing CHIKV’s interaction with host cells remain poorly understood. In this study, we aimed to identify novel host protein interactors of the CHIKV nonstructural protein 3 (nsP3), a critical component of the viral replication complex, using mass spectrometry-based proteomic profiling in liver-derived Huh7 cells. Co-immunoprecipitation followed by LC-MS/MS identified a wide array of host proteins associated with nsP3, revealing 52 proteins classified as high-confidence (FDR of 1%, and unique peptides > 2) CHIKV-specific interactors. A bioinformatic analysis using STRING and Cytoscape uncovered interaction networks enriched in metabolic processes, RNA processing, translation regulation, cellular detoxification, stress responses, and immune signaling pathways. A subcellular localization analysis showed that many interactors reside in the cytosol, while others localize to the nucleus, nucleolus, and mitochondria. Selected novel host protein interactions were validated through co-immunoprecipitation and immunofluorescence assays. Our findings provide new insights into the host cellular pathways hijacked by CHIKV and highlight potential targets for therapeutic intervention. This is the first report mapping direct nsP3–host protein interactions in Huh7 cells during CHIKV infection.

This study presents a novel plasmonic fiber optic sandwich immunobiosensor for the detection of chikungunya, an infectious mosquito-borne disease with chronic musculoskeletal pain and acute febrile illness, by exploiting non-structural protein 3 (CHIKV-nsP3) as a biomarker. A plasmonic sandwich immunoassay for CHIKV-nsP3 was realized on the surface of a compact U-bent plastic optical fiber (POF, 0.5 mm core diameter) with gold nanoparticles (AuNPs) as labels. The high evanescent wave absorbance (EWA) sensitivity of the U-bent probes allows the absorption of the light passing through the fiber by the AuNP labels, upon the formation of a sandwich immunocomplex of CHIKV-nsP3 on the core surface of the U-bent probe region. A simple optical set-up with a low-cost green LED and a photodetector on either end of the U-bent probe gave rise to a detection limit of 0.52 ng mL⁻¹ (8.6 pM), and a linear range of 1–10⁴ ng mL⁻¹ with a sensitivity of 0.1043A_{530 nm}/log(C_nsP3). In addition, the plasmonic POF biosensor shows strong specificity towards the CHIKV-nsP3 analyte in comparison with Pf-HRP2, HIgG, and dengue whole virus. The results illustrate the potential of plasmonic POF biosensors for direct and sensitive point-of-care detection of the chikungunya viral disease.

Chikungunya (CHIK) is a febrile arboviral illness caused by chikungunya virus (CHIKV) and has been identified in more than 60 countries across the globe. A major public health concern, the infection occurs as an acute febrile phase and a chronic arthralgic phase. The disease manifests differently in different age groups that can range from asymptomatic infection in the younger age group to a prolonged chronic phase in the elderly population. The present study was undertaken to evaluate strain-specific pathogenesis of ECSA genotype of CHIKV strains derived from clinical isolates in adult C57BL/6J mice model. The strain that was pathogenic and developed distinct acute and post–acute phase of CHIK infection was further evaluated for dose-dependent pathogenesis. Upon arriving on the optimal dose to induce clinical symptoms in the mice, the disease progression was evaluated across the acute and the post–acute phase of infection for a period of 15 days post–infection in two age groups of mice, namely eight weeks old and 20 weeks old mice groups. Biochemical, hematological, and virology attributes were measured and correlated to morbidity and linked neurotropism and limb thickness in the two age groups. Our results show that CHIKV exhibit strain-specific pathogenesis in C57BL/6J mice. Distinct dissimilarities were observed between the two age groups in terms of pathogenesis, viral clearance and host response to CHIKV infection.

Chikungunya virus (CHIKV) and dengue virus (DENV) are important arboviruses transmitted by Aedes mosquitoes. These viruses are known to coexist within the same vector and coinfect the same host. Although information is available on the mechanism of replication of CHIKV and DENV when present independently in a vector, reports are lacking on the dynamics of virus–vector interactions when these viruses coexist in a mosquito. The current study attempts to understand the perturbations in the proteome of Aedes mosquitoes when infected with CHIKV and DENV either independently or together. Global proteome profiling of chikungunya and dengue mono- and coinfection revealed 28 proteins to be significantly regulated. Validation of the transcripts of these proteins using qRT-PCR indicated differences in the expression patterns between transcript profiling and quantitative proteome analyses. Pathway analysis of the 28 differentially regulated proteins revealed 11 significant pathways, which include oxidative phosphorylation, carbon metabolism, and glycolysis/gluconeogenesis.

Mosquitoes live under the endless threat of infections from different kinds of pathogens such as bacteria, parasites, and viruses. The mosquito defends itself by employing both physical and physiological barriers that resist the entry of the pathogen and the subsequent establishment of the pathogen within the mosquito. However, if the pathogen does gain entry into the insect, the insect mounts a vigorous innate cellular and humoral immune response against the pathogen, thereby limiting the pathogen’s propagation to nonpathogenic levels. This happens through three major mechanisms: phagocytosis, melanization, and lysis. During these processes, various signaling pathways that engage intense mosquito–pathogen interactions are activated. A critical overview of the mosquito immune system and latest information about the interaction between mosquitoes and pathogens are provided in this review. The conserved, innate immune pathways and specific anti-pathogenic strategies in mosquito midgut, hemolymph, salivary gland, and neural tissues for the control of pathogen propagation are discussed in detail.