Temporal Trends in Outbreaks of Chandipura Viral Infection in India: A Systematic Review.

Chandipura virus (CHPV) has emerged as a significant cause of acute encephalitis in India, especially affecting pediatric populations. This study aimed to analyze the temporal trends, clinical characteristics, and epidemiological features of CHPV infections reported in outbreaks across India. A comprehensive literature search on CHPV cases was conducted using Google Scholar, PubMed, and the Cochrane Library. Original research studies on laboratory-confirmed clinical cases of CHPV infections, available as full-text articles, were included. Data on outbreak characteristics, clinical presentations, diagnostics, and epidemiological factors were extracted and analyzed. Six studies met the inclusion criteria. The review revealed a geographical expansion of CHPV outbreaks across India over time, with a consistent seasonal pattern (May to September) coinciding with the monsoon season. CHPV predominantly affects children under 15 years of age, presenting with rapid-onset encephalitis characterized by high fever, altered consciousness, and seizures. Case fatality rates were alarmingly high, ranging from 28.6% to 78.3% within the first 48 hours of symptom onset. Diagnostic approaches evolved over the study period, with increasing use of molecular techniques. Entomological investigations consistently identified sandflies, particularly Phlebotomus argentipes, as potential vectors, though their precise role in transmission remains to be fully elucidated. CHPV is an emerging public health threat, especially for children under 15 years. Early diagnosis is crucial, as CHPV is associated with high mortality within the first 24-48 hours of symptom onset. Challenges include limited long-term follow-up data, potential underreporting of mild cases, and gaps in understanding transmission dynamics.

Chandipura Virus Forms Cytoplasmic Inclusion Bodies through Phase Separation and Proviral Association of Cellular Protein Kinase R and Stress Granule Protein TIA-1.

Negative-strand RNA viruses form cytoplasmic inclusion bodies (IBs) representing virus replication foci through phase separation or biomolecular condensation of viral and cellular proteins, as a hallmark of their infection. Alternatively, mammalian cells form stalled mRNA containing antiviral stress granules (SGs), as a consequence of phosphorylation of eukaryotic initiation factor 2α (eIF2α) through condensation of several RNA-binding proteins including TIA-1. Whether and how Chandipura virus (CHPV), an emerging human pathogen causing influenza-like illness, coma and death, forms IBs and evades antiviral SGs remain unknown. By confocal imaging on CHPV-infected Vero-E6 cells, we found that CHPV infection does not induce formation of distinct canonical SGs. Instead, CHPV proteins condense and co-localize together with SG proteins to form heterogeneous IBs, which ensued independent of the activation of eIF2α and eIF2α kinase, protein kinase R (PKR). Interestingly, siRNA-mediated depletion of PKR or TIA-1 significantly decreased viral transcription and virion production. Moreover, CHPV infection also caused condensation and recruitment of PKR to IBs. Compared to SGs, IBs exhibited significant rapidity in disassembly dynamics. Altogether, our study demonstrating that CHPV replication co-optimizes with SG proteins and revealing an unprecedented proviral role of TIA-1/PKR may have implications in understanding the mechanisms regulating CHPV-IB formation and designing antiviral therapeutics. Importance: CHPV is an emerging tropical pathogen reported to cause acute influenza-like illness and encephalitis in children with a very high mortality rate of ~70%. Lack of vaccines and an effective therapy against CHPV makes it a potent pathogen for causing an epidemic in tropical parts of globe. Given these forewarnings, it is of paramount importance that CHPV biology must be understood comprehensively. Targeting of host factors offers several advantages over targeting the viral components due to the generally higher mutation rate in the viral genome. In this study, we aimed at understanding the role of SGs forming cellular RNA-binding proteins in CHPV replication. Our study helps understand participation of cellular factors in CHPV replication and could help develop effective therapeutics against the virus.

Chandipura viral glycoprotein (CNV-G) promotes Gectosome generation and enables delivery of intracellular therapeutics.

Overexpression of vesicular stomatitis virus G protein (VSV-G) elevates the secretion of EVs known as gectosomes, which contain VSV-G. Such vesicles can be engineered to deliver therapeutic macromolecules. We investigated viral glycoproteins from several viruses for their potential in gectosome production and intracellular cargo delivery. Expression of the viral glycoprotein (viral glycoprotein from the Chandipura virus [CNV-G]) from the human neurotropic pathogen Chandipura virus in 293T cells significantly augments the production of CNV-G-containing gectosomes. In comparison with VSV-G gectosomes, CNV-G gectosomes exhibit heightened selectivity toward specific cell types, including primary cells and tumor cell lines. Consistent with the differential tropism between CNV-G and VSV-G gectosomes, cellular entry of CNV-G gectosome is independent of the Low-density lipoprotein receptor, which is essential for VSV-G entry, and shows varying sensitivity to pharmacological modulators. CNV-G gectosomes efficiently deliver diverse intracellular cargos for genomic modification or responses to stimuli in vitro and in the brain of mice in vivo utilizing a split GFP and chemical-induced dimerization system. Pharmacokinetics and biodistribution analyses support CNV-G gectosomes as a versatile platform for delivering macromolecular therapeutics intracellularly.

Diversity of sandflies in Vidarbha region of Maharashtra, India, a region endemic to Chandipura virus encephalitis.

Background & objectives: Sandflies are implicated as vectors of Chandipura virus (CHPV) (Vesiculovirus: Rhabdoviridae). The virus is prevalent in central India including Vidarbha region of Maharashtra. CHPV causes encephalitis in children below 15 yr of age with case fatality rates ranging from 56 to 78 per cent. The present study was undertaken to determine the sandfly fauna in the CHPV endemic Vidharba region. Methods: A year round survey of sandflies was conducted at 25 sites in three districts of Vidarbha region. Sandflies were collected from their resting sites using handheld aspirators and identified using taxonomical keys. Results: A total of 6568 sandflies were collected during the study. Approximately 99 per cent of the collection belonged to genus Sergentomyia, which was represented by Ser. babu, Ser. bailyi and Ser. punjabensis. Genus Phlebotomus was represented by Ph. argentipes and Ph. papatasi. Ser. babu was the predominant species (70.7%) collected during the study. Ph. argentipes was detected in four villages with 0.89 per cent, whereas Ph. papatasi was detected in only one village with 0.32 per cent of the total collection. CHPV could not be isolated despite processing all the sandflies for virus isolation in cell culture. Interpretation & conclusions: The present study showed influence of higher temperature and relative humidity on sandfly population dynamics. An important observation during the study was the absence or decline in the population of Ph. papatasi and Ph. argentipes in the study area. Surge in Sergentomyia population and their breeding/resting in close vicinity to humans pose a concern as they are known to harbour CHPV and other viruses of public health importance.

MicroRNA-155 triggers a cellular antiviral immune response against Chandipura virus in human microglial cells.

Chandipura virus (CHPV) belongs to the family Rhabdoviridae and has a single-stranded RNA genome that causes encephalitis among children in India's tropical states. Activation of the antiviral immune response upon viral infection is important for the host's defense. In response to CHPV infection, the brain resident macrophages (microglial cells) control the pathogenic insults. The microRNAs (miRNAs) are 22 nts non-coding RNAs that serve as delicate regulators of their target genes at the post-transcriptional level. In this study, we explored miR-155 mediated antiviral response in CHPV infected human microglial cells. The gene and protein expression patterns were studied through quantitative real-time PCR (qPCR) and immunoblotting, respectively. Additionally, miRNA target validation was done by overexpression and knockdown of miR-155. We observed an increased expression of miR-155 in CHPV infected human microglial cells. The upregulated miR-155 suppresses the Suppressor of Cytokine Signalling 1 (SOCS1). Reduced SOCS1, in turn, led to enhanced phosphorylation of Signal Transducer and Activator of Transcription 1 (STAT1) and induction of Interferon-ß (IFN-ß), which promoted the expression of IFN-stimulated gene 54 (ISG54) and IFN-stimulated gene 56 (ISG56). In this study, miR-155 positively modulated the cellular antiviral response by enhancing type I IFN signalling through inhibition of SOCS1 in CHPV infected microglial cells.

Antiviral effect of Favipiravir against Chandipura virus in vitro and in vivo.

Chandipura virus (CHPV) is an emerging encephalitic virus with outbreak potential in a pediatric population. It causes acute encephalitis, with clinical symptoms leading to death within 48-72 h and an alarmingly high case fatality rate up to 55%-78%. Despite the high mortality rate in children, no vaccines or antivirals are currently available; thus, repurposing licensed drugs seems to be one of the attractive therapeutic approaches. Among the various options available, Favipiravir emerged as a promising candidate, and its unique characteristics and clinical efficacy have garnered significant attention and demonstrated considerable potential in the fight against viral diseases. In the current study, we have evaluated the antiviral effect of Favipiravir against CHPV by Plaque reduction assay and viral growth kinetics assay in Vero cells and in vivo effect of drug treatment against lethal viral challenge was analysed in 10-day-old CD1 mice. A dose-dependent reduction in CHPV plaque size and number was observed in Vero cells treated with Favipiravir, with an EC50 of 92.26 µM. Complete inhibition of CHPV replication was observed at 320 µM drug concentration and 50% cytotoxicity (CC50 ) at 4774 µM, indicating a high selectivity index 51.24. In vivo, studies in mice showed 100% survival with 300 mg/kg/day of Favipiravir given orally till seventh-day postinfection. The study provides evidence of the antiviral activity of Favipiravir against CHPV infection, and further clinical evaluation may alleviate the associated mortality.

Chandipura virus changes cellular miRNome in human microglial cells.

Chandipura virus (CHPV) is a neurotropic virus, known to cause encephalitis in humans. The microRNAs (miRNA/miR) play an important role in the pathogenesis of viral infection. The present study is focused on the role of miRNAs during CHPV (strain 1653514) infection in human microglial cells. The deep sequencing of CHPV-infected human microglial cells identified a total of 12 differentially expressed miRNA (DEMs). To elucidate the role of DEMs, the target gene prediction, Gene Ontology term (GO Term), pathway enrichment analysis, and miRNA-messenger RNA (mRNA) interaction network analysis was performed. The GO terms and pathway enrichment analysis provided 146 enriched genes; which were involved in interferon response, cytokine and chemokine signaling. Further, the WGCNA (weighted gene coexpression network analysis) of the enriched genes were discretely categorized into three modules (blue, brown, and turquoise). The hub genes in the blue module may correlate to CHPV induced neuroinflammation. Altogether, the miRNA-mRNA interaction network and WGCNA study revealed the following pairs, hsa-miR-542-3p and FAF1, hsa-miR-92a-1-5p and MYD88, and hsa-miR-3187-3p and TNFRSF21, which may contribute to neuroinflammation during CHPV infection in human microglial cells.

Design of a multi-epitope peptide vaccine candidate against chandipura virus: an immuno-informatics study.

Chandipura virus (CHPV) is an emerging pathogen responsible for acute encephalitic syndrome (AES) in pediatric population in India. Several outbreaks of CHPV have been reported from different states of India since the year 2003. At present there is no vaccine or therapeutic measures available to curtail the disease. In this study, we have identified both T-cell and B-cell epitopes of different antigenic proteins of CHPV like Nucleoprotein (N), Phosphoprotein (P) and Matrix protein (M) along with the immuno-dominant glycoprotein (G) and conducted in silico characterization for the same. The idea is to design a multi-epitope peptide construct using the epitopes, which were found to be non-toxic, non-allergenic and possessing high immunogenicity. The final multi-epitope construct named as: MEC-CHPV, comprised of ß-defensin adjuvant at N-terminal for enhancement of immunogenicity followed by fourteen B-cell epitopes, four Helper T-cell epitopes and six Cytotoxic T-cell epitopes. The characterization of designed construct was carried out in terms of physicochemical parameters, antigenicity and allergenicity. The 3D structure prediction was performed. Molecular docking and molecular-dynamics simulation of MEC-CHPV with Toll like receptors (TLR-3 and TLR-8) showed stable interactions. In silico cloning of MEC-CHPV in pET30a(+) expression vector was also conducted using codon optimization. The in silico immune-simulation indicated a typical immune response against MEC-CHPV when used as a potential vaccine. This study provides a cost-effective and time-saving way to design a peptide vaccine candidate against CHPV using immuno-informatics approach. Development of the MEC-CHPV construct may pave the way for future laboratory experiments.Communicated by Ramaswamy H. Sarma.

Immunoinformatics approach for designing a universal multiepitope vaccine against Chandipura Virus.

Chandipura vesiculovirus (CHPV) is a fast-emerging virus that causes acute encephalitis with a high death rate. Because of its extensive prevalence in African and Asian countries, this infection has become a global hazard, and there is an urgent need to create an effective and non-allergenic vaccine or appropriate treatment to combat it. A vaccine candidate is offered utilizing a computational technique in this study. To build a potential vaccine candidate, viral protein sequences were acquired from the National Center for Biotechnology Information database and evaluated with several bioinformatics techniques to identify B-cell and T-cell epitopes. V1 was shown to be superior in terms of various physicochemical qualities, as well as highly immunogenic and non-allergic. Molecular docking revealed that the CHPV vaccine construct had a greater binding affinity with human Toll-like receptors (TLR-3 and TLR-8) and that it was stable in molecular dynamics simulations. MEC-CHPV was in silico cloned in the pET28a (+) expression vector using codon optimization. The current research identifies potential antigenic epitopes that could be used as vaccine candidates to eradicate the CHPV. This in-silico development of a CHPV vaccine with multiple epitopes could open the path for future rapid laboratory tests.

Chandipura virus induces cell death in cancer cell lines of human origin and promotes tumor regression in vivo.

Chandipura virus (CHPV) is an emerging human pathogen of great clinical significance. In this study, we have investigated the susceptibility pattern of both normal and cancer cell lines of human origin to wild-type (wt) CHPV in order to explore the possibility of developing CHPV as an oncolytic vector (OV). Marked cytopathic effect along with enhanced virus output was observed in cancer cell lines (HeLa, A549, U-138, PC-3, and HepG2) in comparison to normal human adult dermal fibroblast (HADF) cells. At an MOI of 0.1, cancer cell lines were differentially susceptible to CHPV, with cells like HeLa and U-138 having pronounced cell death, while the PC-3 were comparatively resistant. All cell lines used in the study except U-138 restricted CHPV infection to varying degrees with IFN-ß pre-treatment and supplementation of interferon (IFN) could neither activate the IFN signaling pathway in U-138 cells. Finally, U-138 tumor xenografts established in non-obese diabetic severe combined immunodeficiency (NOD/SCID) mice showed significant delay in tumor growth in the CHPV-challenged animals. Thus, targeted cytopathic effect in cancer cells at a very low dose with restricted replication in normal cells offers a rationale to exploit CHPV as an oncolytic vector in the future.

Chandipura virus dysregulates the expression of hsa-miR-21-5p to activate NF-κB in human microglial cells.

BACKGROUND: Chandipura virus (CHPV) is a negative single-stranded RNA virus of the Rhabdoviridae family. CHPV infection has been reported in Central and Western India. CHPV causes acute encephalitis with a case fatality rate of 70 % and mostly affects children below 15 years of age. CHPV infection in brain leads to neuronal apoptosis and activation of the microglial cells. The microRNAs (miRNAs) are small endogenous non-coding RNA that regulate the gene expression. Viral infections perturb the expression pattern of cellular miRNAs, which may in turn affect the expression pattern of downstream genes. This study aims to investigate hsa-miR-21-5p mediated regulation of PTEN, AKT, NF-ĸBp65, IL-6, TNF-α, and IL-1ß, in human microglial cells during CHPV infection. METHODS: To understand the role of hsa-miR-21-5p in CHPV infection, the human microglial cells were infected with CHPV (MOI-0.1). Real-time PCR, western blotting, Luciferase assay, over-expression and knockdown techniques were used to understand the role of hsa-miR-21-5p in the regulation of PTEN, AKT and, NF-ĸBp65, IL-6, TNF-α, and IL-1ß in this study. RESULTS: The hsa-miR-21-5p was found to be upregulated during CHPV infection in human microglial cells. This led to the downregulation of PTEN which promoted the phosphorylation of AKT and NF-ĸBp65. Over-expression of hsa-miR-21-5p led to the decreased expression of PTEN and promoted further phosphorylation of AKT and NF-ĸBp65 in human microglial cells. However, the inhibition of hsa-miR-21-5p using hsa-miR-21-5p inhibitor restored the expression. CONCLUSIONS: This study supports the role of hsa-miR-21-5p in the regulation of pro-inflammatory genes in CHPV infected human microglial cells.

Chandipura Virus' Oncolytic Potential in Experimentally Induced Tumor in Mice.

Chandipura virus (CHPV) is a tropical pathogen, suggesting its involvement in childhood encephalitis syndrome in India. No reports are available in adult human beings for its pathogenicity. Similarly, in adult mice, the virus does not develop pathogenesis by parenteral route except for intracranial route of infection. The virus is remarkably nonpathogenic to adult immunocompromised nude mice. In vitro in tissue culture, the CHPV infects and kills many types of cells. All of these properties could qualify the CHPV to be a candidate virus for tumor therapy. To prove this, an experimentally induced tumor in a mouse was infected with live CHPV. The results showed that intra-tumoral injection reduced the volume of tumor and increased the longevity of the mice. The study concludes that the CHPV may be a safe tumor therapy virus. More precisely, the discovery of CHPV protein with oncolytic potential may lead to the development of novel drugs/therapeutics.

Ribavirin inhibits Chandipura virus replication in Vero cells.

Chandipura virus (CHPV) is an emerging tropical pathogen in India. The virus has been reported to be associated with an acute encephalitis syndrome in young children with a case fatality rate of 55% to 75%. Clinical management with symptomatic treatment is the only option available to treat infected patients. No vaccines are available for prophylaxis. In light of the prophylactic limitations, antiviral therapy would play an important role in control of CHPV infection. In the present study, ribavirin (RBV), an antiviral drug widely accepted for human use and having an antiviral effect on many RNA and DNA viruses, was tested against the CHPV. A screening assay that scores for the virus-mediated plaque formation in the cultured Vero cells was used. RBV exhibited 50% inhibitory concentration (IC50 ) at 89.84 ± 1.8 µM. The drug was very effective when the cells were treated either within an hour postinfection or 4 to 6 hours before infection. The plaque morphology was different in RBV treated cells; the plaques were smaller in size as compared with the plaques in the virus infected cells. The study reports the antiviral activity of RBV against CHPV, and hence, suggests the possible utility of RBV in CHPV infected patients to mitigate the disease. A further clinical trial is needed before introducing the drug for human use against CHPV infection.

Alternative pathway of complement activation has a beneficial role against Chandipura virus infection.

The complement system is a critical component of both innate and adaptive immune responses. It has both protective and pathogenic roles in viral infections. There are no studies regarding the role of complement system in Chandipura virus (CHPV) infection. The current study has investigated the role of complement pathways in the in vitro neutralization of CHPV in Vero E6 cells. Using normal human serum (NHS), heat-inactivated serum (HIS), human serum deficient of complement factor, respective reconstituted serum, assays like in vitro neutralization, real-time PCR, and flow cytometry-based tissue culture-based limited dose assay (TC-LDA) were carried out for assessing the activation of different complement pathways. NHS from 9/10 donors showed complement dependent neutralization, reduction in viral load and decrease in percentage of CHPV-positive cells compared to their HIS counterparts. EGTA or EDTA pretreatment experiments indicated that CHPV neutralization proceeds through the alternative pathway of the complement activation. Our data showed a strong dependence on C3 for the in vitro neutralization of CHPV. Disparity in CHPV neutralization levels between factor B-deficient and reconstituted sera could be attributed to amplification loop/"tick-over" mechanism. Assays using C3, C5, and C8 deficient sera indicated that complement-mediated CHPV neutralization and suppression of CHPV infectivity are primarily through C3 and C5, and not dependent on downstream complement factor C8. With no specific anti-viral treatment/vaccine against Chandipura, the current data, elucidating role of human complement system in the neutralization of CHPV, may help in designing effective therapeutics.

Vector competence of Aedes vittatus (Bigot) mosquitoes from India for Japanese encephalitis, West Nile, Chandipura and Chittoor viruses.

BACKGROUND & OBJECTIVES: Aedes vittatus (Bigot), an anthropophilic mosquito, plays an important role in the maintenance and transmission of yellow fever (YF), dengue (DEN), chikungunya (CHIKV) and Zika (ZIK) viruses in Africa. In India, though natural isolation of none of these viruses was reported from the mosquito, experimental studies have shown vector competence to DEN and CHIK viruses. Despite wide prevalence in India, their potential in transmitting viruses of public health importance viz., Japanese encephalitis (JEV), West Nile (WNV), Chandipura (CHPV), Chittoor (CHITV) etc., has never been investigated. The objective of the present study is to determine the vector potential of the mosquito to these viruses. METHODS: Mosquitoes were infected by intra-thoracic inoculation as well as by oral feeding, and growth kinetics was determined. Virus dissemination to organs was investigated by determining virus in the harvested organs on specified days' post infection (PI). Vector competence was determined by detecting the virus in saliva. RESULTS: Intra thoracic inoculation has shown vector competence of the mosquito to JEV, WNV, CHIV and CHPV. However, using the oral route of infection, replication was observed with only WNV, JEV and CHITV. High degree of WNV replication (6.7log TCID50/ml) with rapid dissemination to wings, legs and salivary glands was seen from 5th day PI onwards. WNV was detected in saliva with a titer of 0.7log10 TCID50/ml on 5th day PI. JEV and CHITV replicated in the mosquito yielding 3log and 4log10 TCID50/ml on 5th and 10th day PI respectively, but virus was not detected in saliva till 15th day PI. INTERPRETATION & CONCLUSION: From the results it is difficult to indict the mosquito as a vector of the viruses studied. However, presence of WNV in saliva of the mosquito shows its potential as a bridge vector and poses a concern especially when virulent WNV strains are circulating in the country.

Vesiculopolins, a New Class of Anti-Vesiculoviral Compounds, Inhibit Transcription Initiation of Vesiculoviruses.

Vesicular stomatitis virus (VSV) represents a promising platform for developing oncolytic viruses, as well as vaccines against significant human pathogens. To safely control VSV infection in humans, small-molecule drugs that selectively inhibit VSV infection may be needed. Here, using a cell-based high-throughput screening assay followed by an in vitro transcription assay, compounds with a 7-hydroxy-6-methyl-3,4-dihydroquinolin-2(1H)-one structure and an aromatic group at position 4 (named vesiculopolins, VPIs) were identified as VSV RNA polymerase inhibitors. The most effective compound, VPI A, inhibited VSV-induced cytopathic effects and in vitro mRNA synthesis with micromolar to submicromolar 50% inhibitory concentrations. VPI A was found to inhibit terminal de novo initiation rather than elongation for leader RNA synthesis, but not mRNA capping, with the VSV L protein, suggesting that VPI A is targeted to the polymerase domain in the L protein. VPI A inhibited transcription of Chandipura virus, but not of human parainfluenza virus 3, suggesting that it specifically acts on vesiculoviral L proteins. These results suggest that VPIs may serve not only as molecular probes to elucidate the mechanisms of transcription of vesiculoviruses, but also as lead compounds to develop antiviral drugs against vesiculoviruses and other related rhabdoviruses.

Structural and cellular biology of rhabdovirus entry.

Rhabdoviruses are enveloped viruses with a negative-sense single strand RNA genome and are widespread among a great variety of organisms. In their membrane, they have a single glycoprotein (G) that mediates both virus attachment to cellular receptors and fusion between viral and endosomal membranes allowing viral genome release in the cytoplasm. We present structural and cellular aspects of Rhabdovirus entry into their host cell with a focus on vesicular stomatitis virus (VSV) and rabies virus (RABV) for which the early events of the viral cycle have been extensively studied. Recent data have shown that the only VSV receptors are the members of the LDL-R family. This is in contrast with RABV for which multiple receptors belonging to unrelated families have been identified. Despite having different receptors, after attachment, rhabdovirus internalization occurs through clathrin-mediated endocytosis (CME) in an actin-dependent manner. There are still debates about the exact endocytic pathway of VSV in the cell and on RABV transport in the neuronal axon. In any case, fusion is triggered in the endosomal vesicle via a low-pH induced structural rearrangement of G from its pre- to its postfusion conformation. Vesiculovirus G is one of the best characterized fusion glycoproteins as the previously reported crystal structures of the pre- and postfusion states have been recently completed by those of intermediates during the structural transition. Understanding the entry pathway of rhabdoviruses may have strong impact in biotechnologies as, for example, VSV G is used for pseudotyping lentiviruses to promote efficient transduction, and VSV is a promising oncolytic virus.

Complement-Mediated Neutralization of a Potent Neurotropic Human Pathogen, Chandipura Virus, Is Dependent on C1q.

Among the innate immune sentinels, the complement system is a formidable first line of defense against pathogens, including viruses. Chandipura virus (CHPV), a neurotropic vesiculovirus of the family Rhabdoviridae, is a deadly human pathogen known to cause fatal encephalitis, especially among children. The nature of interaction and the effect of human complement on CHPV are unknown. Here, we report that CHPV is a potent activator of complement and, thus, is highly sensitive to complement proteins in normal human serum (NHS). Utilizing a panel of specific complement component depleted/reconstituted human serum, we have demonstrated that CHPV neutralization is C3, C4, and C1q dependent and independent of factor B, suggesting the importance of the classical pathway in limiting CHPV. Employing a range of biochemical approaches, we showed (i) a direct association of C1q to CHPV, (ii) deposition of complement proteins C3b, C4b, and C1q on CHPV, and (iii) virus aggregation. Depletion of C8, an important component of the pore-forming complex of complement, had no effect on CHPV, further supporting the finding that aggregation and not virolysis is the mechanism of virus neutralization. With no approved vaccines or treatment modalities in place against CHPV, insights into such interactions can be exploited to develop potent vaccines or therapeutics targeting CHPV.IMPORTANCE Chandipura virus is a clinically important human pathogen of the Indian subcontinent. The rapidity of death associated with CHPV infection in addition to the absence of an effective vaccine or therapeutics results in poor clinical prognosis. The biology of the virus and its interaction with the host immune system, including the complement system, are understudied. Our investigation reveals the susceptibility of CHPV to fluid phase complement and also dissects the pathway involved and the mechanism of virus neutralization. Direct binding of C1q, an important upstream component of the classical pathway of complement to CHPV, and the strong dependency on C1q for virus neutralization highlight the significance of identifying such interactions to better understand CHPV pathogenesis and devise strategies to target this deadly pathogen.

Temperature sensitivity and environmental stability of Chandipura virus.

Chandipura virus (CHPV), a negative-stranded RNA virus of family Rhabdoviridae is endemic in Central India since 1965. The virus gained public health importance when it was held responsible for massive outbreak in 2003-2004 in Maharashtra, Telengana and Gujarat with case fatality rates ranging from 55 to 75% among children. We studied the stability of the virus as well as RNA persistence in samples stored at different temperatures for different periods. CHPV remained infective in sand flies and cell culture supernatants at 4 °C for 8 weeks. At 37 °C CHPV remained viable for 18 days when stored in infected cell supernatant (Minimum essential medium supplemented with 10% fetal bovine serum). However, in infected sand flies stored at 37 °C, the virus lost virulence within a week. CHPV RNA, though lost virulence, could be detected in virus exposed sand flies stored at 37 °C for 13 weeks by real time RT-PCR. Retaining virulence at 37 °C for 18 days in serum containing medium is a matter of concern for laboratories and hospital settings where clinical samples are handled. RNA persistence for prolonged periods in dead sand flies might help in surveillance studies of CHPV in sand flies and will help in resource constraint nations where cold chain management is a concern.

Chandipura Viral Encephalitis: A Brief Review.

INTRODUCTION: In recent years, the Chandipura virus (CHPV) has emerged as an encephalitic pathogen and found associated with a number of outbreaks in different parts of India. Children under 15 years of age are most susceptible to natural infection. CHPV is emerging as a significant encephalitis, causing virus in the Indian subcontinent. Severe outbreaks caused by the virus have been reported from several parts of India. EXPALANATION: In the recent past, the noticeable association of CHPV with pediatric sporadic encephalitis cases as well as a number of outbreaks in Andhra Pradesh (2004, 2005, 2007 and 2008), Gujarat in (2005, 2009-12) and Vidarbha region of Maharashtra (2007, 2009-12) have been documented. Prevalence and seasonal activity of the virus in these regions are established by NIV through outbreak investigations, sero-survey and diagnosis of the referred clinical specimens. Recently CHPV has been isolated from pools of sand flies collected during outbreak investigations in Vidarbha region of Maharashtra. Since its discovery from India and above-mentioned activity of CHPV, it was suspected to be restricted only to India. CONCLUSION: However, CHPV has also been isolated from human cases during 1971-72 in Nigeria, and hedgehogs (Atelerix spiculus) during entomological surveillance in Senegal, Africa (1990-96) and recently referred samples from Bhutan and Nepal and from wild toque macaques (Macaca sinica) at Polonnaruwa, Sri Lanka during 1993 suggest its circulation in many tropical countries. Based on the limited study on vector related report, it appears that sandflies may be the principle vector.