ABSTRACT
Alphaviruses are serious zoonotic threats responsible for significant morbidity, causing arthritis or encephalitis. So far, no licensed drugs or vaccines are available to combat alphaviral infections. About 300,000 chikungunya virus (CHIKV) infections have been reported in 2023, with more than 300 deaths, including reports of a few cases in the USA as well. The discovery and development of small-molecule drugs have been revolutionized over the last decade. Here, we employed a cell-based screening approach using a series of in-house small-molecule libraries to test for their ability to inhibit CHIKV replication. DCR 137, a quinazoline derivative, was found to be the most potent inhibitor of CHIKV replication in our screening assay. Both, the cytopathic effect, and immunofluorescence of infected cells were reduced in a dose-dependent manner with DCR 137 post-treatment. Most importantly, DCR 137 was more protective than the traditional ribavirin drug and reduced CHIKV plaque-forming units by several log units. CHIKV-E2 protein levels were also reduced in a dose-dependent manner. Further, DCR 137 was probed for its antiviral activity against another alphavirus, the Ross River virus, which revealed effective inhibition of viral replication. These results led to the identification of a potential quinazoline candidate for future optimization that might act as a pan-alphavirus inhibitor.
Subject(s)
Chikungunya Fever , Chikungunya virus , Humans , Ross River virus , Cell Line , Antiviral Agents/pharmacology , Chikungunya virus/physiology , Quinazolines/pharmacology , Virus ReplicationABSTRACT
Mpox (previously known as Monkeypox) has recently re-emerged, primarily through human-to-human transmission in non-endemic countries including India. Virus isolation is still considered as the gold standard for diagnosis of viral infections. Here, the qPCR positive skin lesion sample from a patient was inoculated in Vero E6 cell monolayer. Characteristic cytopathic effect exhibiting typical cell rounding and detachment was observed at passage-02. The virus isolation was confirmed by qPCR. The replication kinetics of the isolate was determined that revealed maximum viral titre of log 6.3 PFU/mL at 72 h postinfection. Further, whole genome analysis through next generation sequencing revealed that the Mpox virus (MPXV) isolate is characterized by several unique SNPs and INDELs. Phylogenetically, it belonged to A.2 lineage of clade IIb, forming a close group with all other Indian MPXV along with few from USA, UK, Portugal, Thailand and Nigeria. This study reports the first successful isolation and phenotypic and genotypic characterization of MPXV from India.
Subject(s)
Monkeypox virus , Humans , Asian People , Cytopathogenic Effect, Viral , Genotype , India , Monkeypox virus/genetics , Monkeypox virus/isolation & purification , Monkeypox virus/pathogenicity , South Asian People , Mpox (monkeypox)/diagnosis , Mpox (monkeypox)/genetics , Mpox (monkeypox)/physiopathology , Mpox (monkeypox)/virologyABSTRACT
Kyasanur Forest Disease is a tick-borne flavivirus is endemic in the Southern India. The recent expansion and resurgence of sporadic outbreaks in southern parts of country is the most important concern. Although only formalin inactivated vaccine is available for treatment with limited efficacy the early detection and timely identification is a only way to prevent spread of cases. If the disease can be identified prior to infection in humans like in forest areas from ticks and vectors the disease spread supposed to be managed quickly. Here we have standardized a single tube ready to use dry-down probe free real time RT-PCR targeted against virus envelope gene for detection of KFDV infection. The assay was standardized in liquid format first, later it was converted into dry-down format with addition of stabilizers with a similar sensitivity and specificity (10RNA Copies/rxn). The sensitivity was comparable to the most widely used and accepted diagnostic platform i.e. TaqMan qRT-PCR. However as the reported assay here omit the need of probes makes it cost effective and dry-down reagents makes more stability to the developed assay in this study if compare to TaqMan qPCR. The assay was evaluated with KFD positive samples and healthy sample panel which revealed high concordance with TaqMan qRT-PCR. Stability was unaffected by temperature fluctuations during transportation even in cold chain free conditions, thus reduce the maintenance of strict cold storage. These findings demonstrated that the reported assay is convenient with 100% sensitivity and specificity to TaqMan qPCR. Thus this assay has the potential usefulness for diagnosis KFDV for routine surveillance in resource limited laboratory settings omitting the use costly and heat sensitive TaqMan qRT-PCR reagents without compromising the sensitivity and specificity of the diagnosis assay.
Subject(s)
Encephalitis Viruses, Tick-Borne , Kyasanur Forest Disease , Humans , Encephalitis Viruses, Tick-Borne/genetics , Resource-Limited Settings , Real-Time Polymerase Chain Reaction , India/epidemiology , Sensitivity and SpecificityABSTRACT
AIM: West Nile encephalitis caused by infection with the West Nile virus (WNV) is endemic in many regions of the world and is a global public health threat. The aim of this report was to develop a method using colorimetry-based reverse-transcription loop-mediated isothermal amplification (cRT-LAMP) and RT-LAMP combined with lateral-flow dipstick (LFD) for rapidly detecting WNV in low-infrastructure settings. METHODS AND RESULTS: The primers for the cRT-LAMP and RT-LAMP-LFD assays were designed based on env gene of the WNV. Primers concentration, temperature and time were optimized for cRT-LAMP and RT-LAMP-LFD. The diagnostic performance of the cRT-LAMP and RT-LAMP-LFD assays was evaluated using human serum samples from 110 patients who were clinically suspected to be infected with WNV. The RT-LAMP was performed in a heating block at 63°C for 40 min. The LAMP amplicons were visible in the lateral-flow dipstick within 5 min. The detection limit of the developed cRT-LAMP and RT-LAMP-LFD assays was 10 copies and this assay showed a high degree of specificity for WNV. Compared with quantitative real-time RT-PCR assay, the kappa value of cRT-LAMP and RT-LAMP-LFD were 0.970. CONCLUSIONS: These results showed that the newly developed WNV-specific cRT-LAMP and RT-LAMP-LFD assays can be employed as an alternative method for screening of WN-suspected human samples. The results revealed that the assay could potentially identify the virus without interference from human serum samples. Collectively, all results revealed that cRT-LAMP and RT-LAMP-LFD assays offer a suitable field-based diagnosis of WNV. SIGNIFICANCE AND IMPACT OF THE STUDY: The cRT-LAMP and LAMP-LFD platform for the detection of WNV is rapid, accurate and simple-to-perform. Our present method has not only a short turnaround time but also avoided cross-contamination problem. Moreover, the use of simple lateral flow dipsticks broadens its application potential for the point-of-care use in resource-limited settings during outbreak situations. To the best of our knowledge, this is the first report for the development of cRT-LAMP and LAMP-LFD assays for rapid, simple, specific and sensitive detection of WNV using human clinical samples and EvaGreen dye.
Subject(s)
West Nile virus , Humans , West Nile virus/genetics , Sensitivity and Specificity , Nucleic Acid Amplification Techniques/methods , Molecular Diagnostic Techniques , DNA Primers/geneticsABSTRACT
Kyasanur forest virus disease (KFD) is a major public health concern in India. Its etiology KFD virus causes haemorrhagic fever with severe sequelae in humans. Due to continuous spatiotemporal expansion of KFD in last decade, the incidences of positive cases have been increasing in both humans and primates. Early diagnosis is of prime importance for disease management and epidemiological containment. In the present study, the highly immunogenic Envelope Domain III (EDIII) antigen was produced using prokaryotic expression system with an yield of 8 mg/L. The protein was purified using affinity chromatography and confirmed for its immuno-reactivity by western blot and UPLCMS/MS analysis. The recombinant EDIII was used as an antigen for the standardization of ELISA to detect anti KFD IgM antibodies in humans. The ROC curve was prepared to set the optimum cut-off OD for the assay. The comparative evaluation of the assay with a reference MAC ELISA revealed 86.96% concordance, 82.22% sensitivity and 91.48% specificity. Inter-rater agreement was performed with kappa index revealing significant agreement between the assays. This is the first study using safe recombinant protein antigen-based detection of anti KFDV antibodies in humans. This simple and scalable ELISA assay will be applicable for large scale screening of samples for combating the emerging threats of KFD in newer territories.
Subject(s)
Encephalitis Viruses, Tick-Borne , Kyasanur Forest Disease , Animals , Antibodies, Viral , Enzyme-Linked Immunosorbent Assay/methods , Humans , Immunoglobulin M , Kyasanur Forest Disease/diagnosis , Kyasanur Forest Disease/epidemiology , Recombinant Proteins/geneticsABSTRACT
Presently diagnosis of Crimean Congo Hemorrhagic Fever virus (CCHFV) infection relies on real-time and end-point RT-PCR, and serodiagnostic assay. These assays are time consuming and cannot be used as a routine screening test. The objective of this study was to develop a rapid diagnostic test that could be completed in < 60 minutes. Rapid detection of CCHFV infection is important for faster delivery of appropriate therapeutics, clinical management of patient and also important to contain the outbreak. In the present study, we have developed a rapid and sensitive single tube reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for detection of CCHFV. The limit of detection of RT-LAMP vis-a-vis Real-time RT-PCR assay is 10 RNA copies. Further, CCHFV specific RT-LAMP assay was successfully evaluated with human and tick samples. The assay correctly picked up diverse CCHFV isolates indicating its applicability for different strains. A comparative evaluation of the RT-LAMP assay vis-à-vis with the real-time RT-PCR revealed 100% concordance with 100 % sensitivity and specificity respectively. No cross reactivity with related Flaviviruses and hemorrhagic fever viruses was observed. The assay is a rapid, isothermal, simple to perform molecular diagnostic, which can be performed in a portable heating block device. CCHF RT-LAMP assay can be used in low resource laboratories for monitoring of CCHFV outbreaks in remote rural regions in affected countries.
Subject(s)
Hemorrhagic Fever Virus, Crimean-Congo , Hemorrhagic Fever, Crimean , Hemorrhagic Fever Virus, Crimean-Congo/genetics , Hemorrhagic Fever, Crimean/diagnosis , Humans , Molecular Diagnostic Techniques , Nucleic Acid Amplification Techniques , RNA, Viral/analysis , RNA, Viral/genetics , Reverse Transcription , Sensitivity and SpecificityABSTRACT
Crimean-Congo hemorrhagic fever (CCHF) is an important tick borne zoonotic viral disease of humans. CCHF virus causes sporadic cases of severe illness across a huge geographic area across Africa to Europe to Asia including India. CCHF has emerged as a major public health concern in western Indian states including Gujarat and Rajasthan, where regular human cases were reported since the year 2011. Human serve as the dead-end host, and they gain infection via infected tick bite, in close contact with ruminants and from slaughter house. Currently, the detection of this fatal infection is limited to BSL-4 laboratory which is scarce even in developed economies. Thus, a safe, sensitive assay for early immunodiagnosis is crucial for disease management and containing the outbreak. In this study, the conserved recombinant nucleoprotein was exploited as a safe, scalable alternate antigen for development of indirect IgM and IgG ELISA detection platform. The indirect ELISA was evaluated using suspected clinical samples collected from hotspot areas in India. Comparison with reference MAC ELISA and IgG ELISA revealed a correlation of 95% and 100% respectively. The results indicate that the developed IgM and IgG indirect ELISA has high sensitivity and specificity for detecting CCHFV antibodies among human. These assays are easy to perform and can be employed for high throughput screening of human samples for clinical diagnosis as well as serosurveillance. These assays are also amenable for conversion to low-cost point of care testing formats for application in resource limited settings.
Subject(s)
Hemorrhagic Fever Virus, Crimean-Congo , Hemorrhagic Fever, Crimean , Animals , Antibodies, Viral , Early Diagnosis , Enzyme-Linked Immunosorbent Assay/methods , Hemorrhagic Fever, Crimean/diagnosis , Hemorrhagic Fever, Crimean/epidemiology , Humans , India/epidemiologyABSTRACT
COVID-19 has emerged as global pandemic with largest damage to the public health, economy and human psyche.The genome sequence data obtained during the ongoing pandemic are valuable to understand the virus evolutionary patterns and spread across the globe. Increased availability of genome information of circulating SARS-CoV-2 strains in India will enable the scientific community to understand the emergence of new variants and their impact on human health. The first case of COVID-19 was detected in Chambal region of Madhya Pradesh state in mid of March 2020 followed by multiple introduction events and expansion of cases within next three months. More than 5000 COVID-19 suspected samples referred to Defence Research and Development Establishment, Gwalior, Madhya Pradesh were analyzed during the nation -wide lockdown and unlock period. A total of 136 cases were found positive over a span of three months that included virus introduction to the region and its further spread. Whole genome sequences employing Oxford nanopore technology were generated for 26 SARS-CoV-2 circulating in 10 different districts in Madhya Pradesh state of India. This period witnessed index cases with multiple travel histories responsible for introduction of COVID-19 followed by remarkable expansion of virus. The genome wide substitutions including in important viral proteins were identified. The detailed phylogenetic analysis revealed the circulating SARS-CoV-2 clustered in multiple clades including A2a, A4 and B. The cluster-wise segregation was observed, suggesting multiple introduction links and subsequent evolution of virus in the region. This is the first comprehensive whole genome sequence analysis from central India, which revealed the emergence and evolution of SARS-CoV-2 during thenation-wide lockdown and unlock.
Subject(s)
COVID-19/diagnosis , Mutation, Missense , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics , COVID-19/epidemiology , COVID-19/virology , Evolution, Molecular , Genome, Viral/genetics , India , Multiplex Polymerase Chain Reaction/methods , Pandemics/prevention & control , Phylogeny , SARS-CoV-2/classification , SARS-CoV-2/physiology , Whole Genome Sequencing/methodsABSTRACT
Crimean-Congo hemorrhagic fever (CCHF) virus, a highly pathogenic viral agent is responsible for severe fatal hemorrhagic infections in many parts of the world. The early diagnosis of CCHF infection is important for successful clinical management and epidemiological control. The nucleoprotein (NP) of CCHFV being highly conserved and immunogenic is used as early diagnostic marker. In this study, we report a rapid and sensitive double antibody based antigen capture ELISA to detect Crimean-Congo hemorrhagic fever virus (CCHFV). Highly specific polyclonal and monoclonal antibody against NP has been generated and used as capture and detector antibody respectively. The assay was able to detect viral nucleoprotein in different matrices including human serum, ticks and culture supernatant. The detection limit of the developed sandwich ELISA assay was 25 ng of purified antigen. Comparison with a real time RT-PCR revealed its detection limit to be 1000 genome equivalents of CCHFV. Further the assay was comparatively evaluated with a commercial kit employing gamma irradiated CCHFV, revealing a sensitivity and specificity of 100%. This newly developed sandwich ELISA (sELISA) with high sensitivity and specificity could be used as an efficient method for the detection of CCHF virus in humans, ticks and culture supernatant. The assay will be useful as alternate tool for diagnosis of acute infection and is amenable for screening of large scale samples in resource limited settings.
Subject(s)
Antibodies, Viral/metabolism , Hemorrhagic Fever Virus, Crimean-Congo/immunology , Hemorrhagic Fever, Crimean/diagnosis , Animals , Antibodies, Viral/blood , Antibodies, Viral/isolation & purification , Antibody Specificity , Cross Reactions/immunology , Diagnostic Tests, Routine/methods , Enzyme-Linked Immunosorbent Assay/methods , Female , HEK293 Cells , Hemorrhagic Fever, Crimean/blood , Hemorrhagic Fever, Crimean/immunology , Humans , Mice , Mice, Inbred BALB C , Rabbits , Time FactorsABSTRACT
SIGNIFICANCE: Kyasanur forest disease (KFD), a re-emerging tick-borne viral disease, causes severe hemorrhagic fever in humans and nonhuman primates. KFD virus (KFDV) is a member of the genus Flavivirus. KFD is now increasingly reported outside its endemic zone in India. Rapid and specific detection of the KFDV plays a critical role in containment of the outbreak. The diagnosis of KFD currently relies on real-time RT-PCR, nested RT-PCR, end point RT-PCR, and serodiagnostic assay. These assays are tedious, time-consuming, and cannot be used as a routine screening platform. OBJECTIVE: The present study was aimed to develop a one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for molecular diagnosis of KFD. DESIGN: The gene amplification reaction was accomplished by incubation at a constant temperature of 63°C for 60min. RESULTS: The limit of detection of RT-LAMP assay was 10 copies. KFD RT-LAMP assay was successfully evaluated with diverse host samples including humans, monkeys, and tick. The assay correctly picked up different KFD isolates indicating its applicability for divergent strains. Comparative evaluation of RT-LAMP assay with quantitative TaqMan real-time RT-PCR revealed 100% concordance. No cross-reaction with related flavi and other hemorrhagic fever viruses was observed, indicating its high specificity. CONCLUSION AND RELEVANCE: The RT-LAMP test developed in this study will serve as a rapid, sensitive alternate detection method for KFDV infection and would be useful for high throughput screening of clinical samples in resource limited areas during outbreaks.
Subject(s)
Encephalitis Viruses, Tick-Borne , Animals , Encephalitis Viruses, Tick-Borne/genetics , Molecular Diagnostic Techniques , Nucleic Acid Amplification Techniques , Real-Time Polymerase Chain Reaction , Reverse Transcription , Sensitivity and SpecificityABSTRACT
Background & objectives: Due to the absence of specific drugs or vaccines for Ebola virus disease, rapid, sensitive and reliable diagnostic methods are required to control the transmission chain of the disease and for better patient management. Isothermal amplification of nucleic acids has emerged as a promising alternative in which rapid and efficient amplification is achieved at a constant temperature without the thermal cycling required in PCR. Methods: A one-step single-tube accelerated quantitative reverse trascription loop-mediated isothermal amplification (RT-LAMP) assay was developed by targeting the NP gene of 2014 Zaire Ebola virus (ZEBOV). The RT-LAMP assay was found to be specific for ZEBOV, without having any cross-reactivity with related haemorrhagic fever viral agents. Results: The comparative evaluation of Ebola virus NP gene-specific RT-LAMP assay with reverse transcription (RT) - PCR and TaqMan real-time RT-PCR demonstrated that RT-LAMP was 10-1000 folds more sensitive than TaqMan real-time RT-PCR and conventional RT-PCR, respectively, with a detection limit of 1 copy number. In the absence of real-world clinical samples, the feasibility of Ebola virus RT-LAMP assay for clinical diagnosis was evaluated with different body fluids including serum, urine, saliva, semen and stool samples from healthy human volunteers spiked with gamma-irradiated ZEBOV 2014 obtained from Robert Koch Institute, Berlin, Germany, through the European Network for Diagnostics of Imported Viral Diseases. The Ebola virus RT-LAMP assay could correctly be picked up the spiked samples up to 1 copy of viral RNA without having any matrix interference. The monitoring of gene amplification can also be visualized with the naked eye by using SYBR Green I fluorescent dye. Interpretation & conclusions: Thus, due to easy operation without a requirement of sophisticated equipment and skilled personnel, the RT-LAMP assay reported here is a valuable tool as a point-of-care diagnosis for the rapid and real-time detection of Ebola virus in resource-limited healthcare settings of developing countries.
Subject(s)
Ebolavirus , Hemorrhagic Fever, Ebola , Ebolavirus/genetics , Gene Amplification , Hemorrhagic Fever, Ebola/diagnosis , Hemorrhagic Fever, Ebola/genetics , Humans , Molecular Diagnostic Techniques , Nucleic Acid Amplification Techniques/methods , Nucleoproteins/genetics , RNA, Viral/analysis , RNA, Viral/genetics , Reverse Transcription/genetics , Sensitivity and SpecificitySubject(s)
COVID-19/epidemiology , Communicable Disease Control , Respiratory Tract Infections/epidemiology , Respiratory Tract Infections/virology , Arboviruses/genetics , Arboviruses/physiology , COVID-19/prevention & control , COVID-19/virology , Coinfection/epidemiology , Coinfection/virology , Humans , Pandemics , Public Health , SARS-CoV-2/physiologyABSTRACT
The molecular detection system has evolved over last two decades and is rapidly replacing the conventional confirmatory techniques in diagnostic virology. However the major limitation in implementation of available molecular detection assays is the non availability of field deployable nucleic acid isolation platform coupled with gene amplification technique. The rapid and early molecular detection is crucial for employing effective measure against many viral infections. The re-emergence of chikungunya virus (CHIKV) has led to epidemics since 2004 in several parts of the world including India. The main association of CHIKV with severe arthritis and long-lasting arthralgia and closely mimics symptoms of Dengue and Zika virus infection requiring laboratory confirmation. In this study, a simple magnetic bead based ribonucleic acid extraction method was optimized, which was coupled with isothermal polymerase spiral reaction (PSR) technique for early and rapid detection. Subsequently, the polymerase spiral reaction reagents were converted to dry down format that led to a rapid user friendly field compatible sample processing to answer method for rapid and onsite detection of Chikungunya virus. Both the methods were evaluated with a panel of clinical samples. The sensitivity of the assays were compared with available commercial viral RNA extraction platform and qRT-PCR. The in-house nucleic acid extraction system based on magnetic bead followed by dry down RT-Polymerase Spiral Reaction assay was found to be highly sensitive with 10 copies of RNA as limit of detection in CHIKV clinical specimens. With respect to other closely related viruses no cross reactivity was observed. This novel methodology has the potential to revolutionize the diagnosis of infectious agents in resource limited settings around the world.
Subject(s)
Chikungunya Fever/diagnosis , Chikungunya virus/genetics , Nucleic Acid Amplification Techniques/standards , RNA, Viral/isolation & purification , Silicon Dioxide/chemistry , Benzothiazoles , Chikungunya Fever/blood , Chikungunya Fever/virology , Diamines , Fluorescent Dyes/chemistry , Humans , Limit of Detection , Magnets , Organic Chemicals/chemistry , Quinolines , RNA, Viral/blood , RNA, Viral/genetics , RNA-Directed DNA Polymerase/chemistryABSTRACT
Recurrent outbreaks of Crimean-Congo hemorrhagic fever (CCHF) virus infection in different parts of world are a major global health concern. The CCHF viral infection is associated with severe hemorrhagic fevers and mortality up to 40%. More than 30 countries in Asia, Europe and Africa are affected with CCHF infection. Prevention of infection through vaccine becomes more important when no effective antiviral and associated therapies are available. Further ticks play a crucial role in maintenance and transmission of CCHFV. Therefore, the control of transmission by ticks is warranted for ultimate prevention of outbreak. The study employed a series of immunoinformatics approaches to design novel multiepitope vaccine targeting highly immunodominant epitopes of major structural proteins (Nucleoprotein and Glycoprotein complex) of CCHFV. Vaccine was designed by incorporating linear and conformational B cell, helper and cytotoxic T cell epitopes from these crucial immunogenic proteins adjoined with appropriate linkers and adjuvant. This vaccine construct was also complemented with a highly immunogenic and conserved protective tick salivary antigen named subolesin to impart dual activity as a unique transmission blocking vaccine. The B-cell peptides were also experimentally validated. The designed vaccine was further in silico validated for its physiochemical properties, allergenicity and immunogenicity etc. The proposed candidate vaccine construct has the potential to function both as a vaccine against CCHF virus as well as a universal anti-tick vaccine.
Subject(s)
Hemorrhagic Fever Virus, Crimean-Congo , Hemorrhagic Fever, Crimean , Ticks , Vaccines , Animals , Computer Simulation , Europe , Hemorrhagic Fever, Crimean/prevention & controlABSTRACT
Crimean-Congo hemorrhagic fever (CCHF) is a re-emerging zoonotic viral disease prevalent in many parts of Asia, Europe, and Africa. The causative agent, Crimean-Congo hemorrhagic fever orthonairovirus (CCHFV), is transmitted through hard ticks. Tick vectors especially belonging to the Hyalomma species serve as the reservoir and amplifying host. The vertebrate animals including sheep, goat, and bovine act as a short-lasting bridge linking the virus and ticks. CCHFV causes fatal hemorrhagic fever in humans. Humans are usually infected with CCHFV either through the bite of infected ticks or by close contact with infected animals. Immunological assays, primarily enzyme-linked immunosorbent assay (ELISA) using whole viral antigen, are widely used for serosurveillance in animals. However, the whole virus antigen poses a high biohazard risk and can only be produced in biosafety level 4 laboratories. The present study focuses on the development and evaluation of safe, sensitive, and specific IgG indirect enzyme-linked immunosorbent assay (iELISA) using recombinant nucleoprotein (NP) of CCHF virus as an antigen. The codon-optimized NP gene sequence was synthesized, cloned, and expressed in pET28a+ vector. The recombinant NP was purified to homogeneity by affinity chromatography and characterized through Western blot and MALDI-TOF/MS analysis. The characterized protein was used to develop an indirect IgG microplate ELISA using a panel of animal sera. The in-house ELISA was comparatively evaluated vis-à-vis a commercially available ELISA kit (Vector-Best, Russia) with 76 suspected samples that revealed a concordance of 90% with a sensitivity and specificity of 79.4 and 100%, respectively. The precision analysis revealed that the assay is robust and reproducible in different sets of conditions. Further, the assay was used for serosurveillance in ruminants from different regions of India that revealed 18% seropositivity in ruminants, indicating continued circulation of virus in the region. The findings suggest that the developed IgG iELISA employing recombinant NP is a safe and valuable tool for scalable high-throughput screening of CCHFV-specific antibodies in multiple species.
ABSTRACT
Human infections caused by West Nile virus (WNV) mostly remain subclinical and self-limited. However, nearly 20% infected people suffer from febrile illness and very few of them (<1%) may get neuroinvasive illness. Mortality has been reported among children. India somehow has reported very less number of WNV cases in the past. We collected cerebrospinal fluid (CSF) samples from 75 pediatric age group patients clinically suffering from acute encephalitis syndrome. Three of these samples were positive by reverse transcriptase polymerase chain reaction using pan flavivirus primers. On sequencing of the 212 bp long-amplified fragment, it was found to be WNV belonging to lineage 1. This is probably the first report of WNV causing encephalitis from this central part of India.
Subject(s)
Acute Febrile Encephalopathy/virology , Antibodies, Viral/blood , West Nile Fever/complications , West Nile Fever/epidemiology , Acute Febrile Encephalopathy/cerebrospinal fluid , Acute Febrile Encephalopathy/epidemiology , Adolescent , Child , Child, Preschool , Female , Humans , Immunoglobulin M/blood , India/epidemiology , Infant , Male , RNA, Viral/genetics , West Nile Fever/cerebrospinal fluid , West Nile virusABSTRACT
Chikungunya virus has emerged as one of the most important global arboviral threats over the last decade. Inspite of large scale morbidity, with long lasting polyarthralgia, so far no licensed vaccine or antiviral is available. CHIKV nsP2 protease is crucial for processing of viral nonstructural polypeptide precursor to release enzymes required for viral replication, thus making it a promising drug target. In this study, high cell density cultivation (HCDC) of Escherichia coli in batch process was carried out to produce rCHIKV nsP2pro in a cost-effective manner. The purified nsP2pro and fluorogenic peptide substrate have been adapted for fluorescence resonance energy transfer (FRET) based high throughput screening (HTS) assay with Z' value and CV of 0.67 ± 0.054 and <10% respectively. We used this cell free HTS system to screen panel of metal ions and its conjugate which revealed zinc acetate as a potential candidate, which was further found to inhibit CHIKV in Vero cells. Scale-up process has not been previously reported for any of the arboviral nonstructural enzymes. The successful scale-up method for viral protease together with a HTS assay could lead to the development of industrial level large-scale screening platform for identification of protease inhibitors against emerging and re-emerging viruses.
Subject(s)
Cysteine Endopeptidases/metabolism , High-Throughput Screening Assays/methods , Protease Inhibitors/pharmacology , Virus Replication/drug effects , Animals , Antiviral Agents/pharmacology , Chikungunya virus/enzymology , Chikungunya virus/physiology , Chlorocebus aethiops , Cysteine Endopeptidases/chemistry , Cysteine Endopeptidases/genetics , Escherichia coli/metabolism , Fluorescence Resonance Energy Transfer , Recombinant Proteins/biosynthesis , Recombinant Proteins/chemistry , Recombinant Proteins/isolation & purification , Substrate Specificity , Vero Cells , Zinc Acetate/pharmacologyABSTRACT
Five complete (H1N1)pdm09 viral sequences were recovered from hospitalized individuals during the 2015 influenza outbreak by metagenomic sequencing. Four of the genomes are from oropharyngeal swabs, and one is from an isolate. All five sequences belong to an emerging 6B clade. Studying them further is critical for outbreak preparedness.
ABSTRACT
BACKGROUND: The West Nile Virus (WNV) has emerged as one of the most significant arboviral infection in many parts of the world and is associated with the encephalitis affecting mainly human and horses. In spite of the fact that the WNV is threat for the public health, there is no vaccine or therapeutic available for the treatment of WNV. METHODS: In this study, we tested a novel RNA interference based technique to inhibit WNV replication in Vero cells. Two siRNAs were designed against the NS2A and NS5 regions of WNV which are highly conserved among Flaviviruses as it play important role in apoptosis and in viral replication respectively. In addition to this, dual functional siRNA is designed by joining an immunostimulatroy motif with the NS2A and NS5 specific siRNA. The antiviral activity was evaluated by detecting both the infectious virus and its genome. RESULTS: The bifunctional siRNA resulted in significant reduction of virus titre in siRNA transfected cells as compared to controls. The antiviral efficacy was most effective at 48hr post infection. These results were in accordance with the quantitative RT-PCR assay revealing similar reduction in WNV genomic RNA. The expression of housekeeping gene was not affected by the siRNA indicating no off target effect and non-interference in cellular mechanism. CONCLUSION: Thus, this bifunctional siRNA intervention paves the new way for therapeutic treatment of WNV disease.
Subject(s)
Antiviral Agents/administration & dosage , RNA, Small Interfering/genetics , Viral Nonstructural Proteins/antagonists & inhibitors , Virus Replication , West Nile Fever/prevention & control , West Nile virus/genetics , Animals , Chlorocebus aethiops , Cytopathogenic Effect, Viral , RNA Interference , Vero Cells , Viral Nonstructural Proteins/genetics , West Nile Fever/genetics , West Nile Fever/virologyABSTRACT
Influenza A viruses has been associated with severe global pandemics of high morbidity and mortality with devastating impact on human health and global economy. India witnessed a major outbreak of influenza A(H1N1)pdm09 in 2015. This study comprises detailed investigation of cases died of influenza A(H1N1)pdm09 virus infection during explosive outbreak of 2015, in central part of India. To find out presence of drug resistant virus among patients who died of influenza A(H1N1)pdm09 virus infection and to find out presence of other mutations contributing to the morbidity and mortality. Twenty-two patients having confirmed influenza A(H1N1)pdm09 infection and subsequently died of this infection along with 20 non fatal cases with influenza A(H1N1)pdm09 infection were included in the study. Samples were investigated through RT-PCR/RFLP analysis, followed by nucleotide cycle sequencing of whole NA gene for detection of H275Y amino acid substitution in NA gene responsible for oseltamivir drug resistance. Out of 22 fatal cases, 6 (27.27%) were found to harbor oseltamivir resistant virus strains, whereas the H275Y mutation was not observed among the 20 non fatal cases. Amino acid substitution analysis of complete NA gene revealed V241I, N369K, N386K substitution in all strains playing synergistic role in oseltamivir drug resistance. High morbidity and mortality associated with influenza A(H1N1)pdm09 viruses can be explained by presence of drug resistant strains circulating in this outbreak. Presence of Oseltamivir resistant influenza A(H1N1)pdm09 viruses is a cause of great concern and warrants continuous screening for the circulation of drug resistant strains.