Spread of a Novel Indian Ocean Lineage Carrying E1-K211E/E2-V264A of Chikungunya Virus East/Central/South African Genotype across the Indian Subcontinent, Southeast Asia, and Eastern Africa

Chikungunya and other viral arthritis

Several viruses cause acute and chronic arthritis. Millions of people suffered from Chikungunya(CHIK) during the recent epidemics/outbreaks in Asia, Africa and the Americas. Almost 20-40 % failed to recover completely and suffered from chronic pain and arthritis sequel. A wide spectrum of clinical phenotypic arthritis was described. Non-specific arthralgias(NSA) and soft tissue pains were predominant although inflammatory arthritis (mostly undifferentiated)(IA-U) was substantial. Specifically, rheumatoid arthritis(RA) and spondyloarthritis(SpA) like disorders were described. The frequency of biomarkers such as rheumatoid factor(RF) was low. Arthritis was mostly non-erosive in population studies. Abnormal immune mechanisms and persistent specific CHIK virus (CHIKV) IgM and IgG antibodies were shown. The etiopathogenetic evidence was divided between intense joint tissue inflammation due to prolonged virus persistence and abnormal autoimmune mechanisms. There was no specific therapy. The symptomatic management was often combined with an empirical use of disease modifying anti rheumatoid drugs and steroids. Substantial research is required to address knowledge gaps and unravel evidence-based medicine.

Inactivated Viral Vaccine BBV87 Protects Against Chikungunya Virus Challenge in a Non-Human Primate Model

Chikungunya virus (CHIKV) is an alphavirus transmitted by mosquitos that poses a threat to global public health and for which there is an urgent need for widespread access to globally licensed vaccines. Here, we demonstrate that an inactivated CHIKV vaccine (BBV87) protects against systemic infection with CHIKV in a non-human primate (NHP) challenge model. Groups of five cynomolgus macaques received two doses of 20 µg BBV87 vaccine or saline alone (28 days apart). Twenty-eight days after the second immunisation, all animals were challenged with CHIKV. All controls were productively infected with detectable viremia and pathological responses following challenge, including altered thermoregulation, haematological and cytokine changes. Critically, the histopathological analysis of finger joints identified areas of inflammation in the synovium. By contrast vaccinated macaques had no detectable viremia and none of the pathological changes were reported in control animals. This study demonstrates that a 20 µg dose of BBV87 vaccine confers robust protection in vivo, both on the acquisition of infection and pathology.

CHIKV mRNA vaccines encoding conserved structural/envelope proteins confer broad cross-lineage protection against infection

With the broad spread of the chikungunya virus (CHIKV), there is an increasing demand for more effective and broadly protective vaccines. Here, we designed CHIKV mRNA vaccines containing full-length structural proteins or part of structural proteins (envelope proteins) based on conserved sequences from 769 viral strains encompassing four lineages. The vaccine induced strong cellular and humoral immune responses in BALB/c mice and provided robust protection. Immunization of BALB/c mice with either of the two vaccines induced high levels of neutralizing antibodies against pseudoviruses from four distinct lineages, highlighting their potential for broad cross-lineage protective efficacy. Immunoglobulin repertoire analysis revealed two important BCR V-J gene combinations, IgHV1-4-IgHJ3 and IgHV1-4-IgHJ2, and lineage-specific immunity analysis revealed significant upregulation of TCRs containing V19 and V20. BCR and TCR immunodiversity may be a potential reason for the broad-spectrum protection against CHIKV afforded by the vaccine. In A129 mice, it elicited lower levels of neutralizing antibodies but prevented mouse mortality and cleared chronic infection. In the rhesus macaque model, both vaccines elicited a certain level of humoral and cellular immune responses and protected the rhesus macaques from the CHIKV challenge. In conclusion, the results from both mouse and rhesus macaque models indicate that the vaccine could be a candidate for clinical use against CHIKV.

Generation of RNA aptamers against chikungunya virus E2 envelope protein

Nucleic acid aptamers are a promising drug modality, whereas the generation of virus-neutralizing aptamers has remained difficult due to the lack of a robust system for targeting the viral particles of interest. Here, we took advantage of our latest platform technology of Systematic Evolution of Ligands by EXponential enrichment (SELEX) with virus-like particles (VLPs) and targeted chikungunya virus (CHIKV) as a model, the pathogenic reemerging virus with an unmet need for control. The identified aptamer against CHIKV-VLPs, Apt#1, and its truncated derivatives showed neutralizing activity with nanomolar IC50 values in a cell-based assay system using a pseudoviral particle of CHIKV (CHIKVpp). An antiviral-based chemical genetics approach revealed significant competition of Apt#1 with suramin, a reported interactant with domain A of the E2 envelope protein (E2DA), in both CHIKVpp and surface plasmon resonance (SPR) analyses, predicting E2DA to be the Apt#1 interface. In addition, Apt#1 interfered with the attachment of CHIKVpp, collectively suggesting its property as an attachment inhibitor via E2DA of CHIKV. Thus, the generation of the VLP-targeted aptamers proved to contribute to anti-CHIKV strategies and confirmed the utility of the platform as a novel and viable option for the development of neutralizing agents against viral particles of interest.IMPORTANCEOur latest SELEX technology using VLPs has generated aptamers that bind the native conformation of the incorporated envelope protein and achieve the virus binding and neutralizing effects. Indeed, the aptamer-probed target E2DA is a representative neutralization site on the surface of the viral particle, validating the utility of the VLP-driven procedure. Simultaneously, the enhanced antiviral effects of the aptamer in combination with approved drugs using the CHIKVpp assay with human cells indicated potential therapeutic strategies that are expected to help address unmet needs in CHIKV control. The robust affinity of the aptamer to viral particles demonstrated by SPR analysis can also lead to conjugates with antivirals as guiding molecules and aptasensors for diagnostic tools. Overall, our VLP-based method provided anti-CHIKV as well as a versatile platform applicable to other emerging and reemerging viruses, in preparation for outbreaks with the need for rapid development of antiviral strategies as next-generation theranostics.

Drug repositioning as a promising approach for the eradication of emerging and re-emerging viral agents

The global impact of emerging and re-emerging viral agents during epidemics and pandemics leads to serious health and economic burdens. Among the major emerging or re-emerging viruses include SARS-CoV-2, Ebola virus (EBOV), Monkeypox virus (Mpox), Hepatitis viruses, Zika virus, Avian flu, Influenza virus, Chikungunya virus (CHIKV), Dengue fever virus (DENV), West Nile virus, Rhabdovirus, Sandfly fever virus, Crimean-Congo hemorrhagic fever (CCHF) virus, and Rift Valley fever virus (RVFV). A comprehensive literature search was performed to identify existing studies, clinical trials, and reviews that discuss drug repositioning strategies for the treatment of emerging and re-emerging viral infections using databases, such as PubMed, Scholar Google, Scopus, and Web of Science. By utilizing drug repositioning, pharmaceutical companies can take advantage of a cost-effective, accelerated, and effective strategy, which in turn leads to the discovery of innovative treatment options for patients. In light of antiviral drug resistance and the high costs of developing novel antivirals, drug repositioning holds great promise for more rapid substitution of approved drugs. Main repositioned drugs have included chloroquine, ivermectin, dexamethasone, Baricitinib, tocilizumab, Mab114 (Ebanga™), ZMapp (pharming), Artesunate, imiquimod, saquinavir, capmatinib, naldemedine, Trametinib, statins, celecoxib, naproxen, metformin, ruxolitinib, nitazoxanide, gemcitabine, Dorzolamide, Midodrine, Diltiazem, zinc acetate, suramin, 5-fluorouracil, quinine, minocycline, trifluoperazine, paracetamol, berbamine, Nifedipine, and chlorpromazine. This succinct review will delve into the topic of repositioned drugs that have been utilized to combat emerging and re-emerging viral pathogens.

Microbiological Investigations for Chikungunya Virus in Children With Acute Encephalitis Syndrome in a Non-Outbreak Setting in Southern India

Chikungunya virus (CHIKV) is an emerging cause of acute encephalitis syndrome (AES) in India, with limited data on its role in childhood AES in southern India. We systematically evaluated children with AES in southern India during a non-epidemic period for CHIKV. Serum and cerebrospinal fluid (CSF) samples were tested for CHIKV using IgM ELISA and real-time reverse transcriptase PCR. Amplicon sequencing was performed on PCR-positive samples. Clinical and laboratory features were compared between children with and without CSF CHIKV positivity (PCR/IgM antibodies). Of 376 children with AES, 20 (5.3%) had positive CHIKV tests. Co-infections were common, particularly with scrub typhus. Children presented with diverse symptoms affecting various organ systems. Neurological manifestations included meningism, seizures, cerebellar signs, behavioral abnormalities, cranial nerve involvement, involuntary movements, and hemiparesis/hemiplegia. Children with CSF CHIKV positivity showed more focal neurological deficits and transaminitis, and less musculoskeletal symptoms. Sequencing confirmation of CHIKV was made in all patients with positive CHIKV PCR, revealing a close relationship with 2016 Kenyan and Indian strains, albeit in a different clade within the East/Central/South African genotype. Along with important mutations known to impact CHIKV infectivity, four novel amino acid substitutions were detected in envelope protein coding regions. Our findings underscore the importance of routine and comprehensive CHIKV testing for children with AES, irrespective of season/outbreak. The high rate of co-infections warrants further research. Continued genomic surveillance is essential to monitor emerging mutations with epidemic potential, increased severity and the risk of neurological disease.

Continuous detection of Chikungunya Virus in a passive surveillance system in southern Thailand, 2012-2019

Chikungunya virus (CHIKV) infections are distributed across the globe, causing significant and, often, lasting morbidity. CHIKV vaccines are in development, but their evaluation is limited by the unpredictability of CHIKV transmission, which classically manifests as explosive epidemics separated by variable interepidemic periods. A passive surveillance study for undifferentiated febrile illness was established in southern Thailand in 2012 and is ongoing. Among 1466 febrile individuals with acute and convalescent specimens, 398 (27.1%) had molecular or serological evidence of acute CHIKV infection. The proportions of participants confirmed to have CHIKV infection differed by year, being highest during epidemic periods (41.1% in 2018-2019, corresponding to a large regional CHIKV outbreak, compared to 19.3% in 2012-2017). These data suggest persistent circulation of CHIKV in the study area, though additional studies are needed to confirm these findings and to discern whether this persistence reflects widespread, low-level transmission or migrating bursts of focal epidemic activity.

Emergence of ECSA-IOL E1-K211E/E2-V264A Lineage of Chikungunya virus during Malaysian 2021 outbreak

BACKGROUND

Chikungunya cases was reported to be on the rise in Malaysia from 2019 to 2021. Although potential endemicity was described previously, genotype shift during 2008 outbreak originating from the 2004 Indian Ocean Islands outbreak presents the probability of current CHIKV spread from neighboring countries. This is due to the prevalence of the new IOL sub-lineage which consists of E1-226A wildtype or reverted strains that are circulating in the Indian subcontinent before spreading to neighboring Thailand during 2018-2019 outbreak.

METHOD

In this study, samples received mostly from the Tangkak, Johor were analyzed. A total 56 CHIKV positive serum samples received in 2021 by Institute of Medical Research Malaysia (IMR), were collected based on sample selection criteria. Selected samples were subjected to total RNA extraction, whole-genome sequencing as well as bioinformatic analysis such as phylogenetic, variant and mutation analysis.

RESULTS

Based on the genomic and phylogenetic analysis, the CHIKV samples from 2021 outbreak were of ECSA-IOL genotype. Genome similarity analysis also revealed that these CHIKVs were highly similar to 2018-2019 outbreak strain from Thailand. In comparison to the 2008 outbreak CHIKV isolate, the current CHIKVs lacked the E1-A226V mutation and harbored the new E1-K211E/E2-V264A sub-linage mutation. Since the E1-K211E/E2-V264A mutation facilitates adaptation to Ae. aegypti as opposed to the E1-A226V mutation which improves adaptation to Ae. albopictus, the emergence 2021 CHIKV outbreak in Malaysia can be postulated due to vector shift. Interestingly, a novel nsP3-T441A/V mutation detected in this study, may also play a role in virus transmission, pathogenicity, fitness and vector adaptation.

CONCLUSION

In summary, the current CHIKV outbreak are strains originated from the Indian subcontinent through Thailand which may have capitalized on vector shifting by adapting to Ae. aegypti. The presence of novel nsP3-T441A/V mutation may also contribute to the spread of this virus across peninsular Malaysia.

Genetic characterization and phylogenetic analysis of Chikungunya Virus: A case from Jeddah during the COVID-19 Pandemic

Chikungunya fever is an arboviral disease caused by the Chikungunya virus (CHIKV), which is classified into three genotypes, namely Asian, West African, and East/Central/South African (ECSA). Due to the frequency and severity of CHIKV outbreaks, it is crucial to genetically characterize the virus, especially in non-endemic regions. This report describes a case and genome characterization of CHIKV from a case that was detected in Jeddah (in 2021) during the COVID-19 pandemic. CHIKV was identified in a 32-year-old male patient in Jeddah, originally from India, who presented with fever, myalgia, malaise, and fatigue and was initially suspected of having dengue. The patient had no history of travel in the fortnight prior to his presentation. Treatment included paracetamol, saline, and vitamin C, which is important for the host immune response and detoxification of viral products. The genome of CHIKV was sequenced using various techniques and bioinformatics tools. Amino acid mutations were studied. Phylogenetic analysis showed that the CHIKV strain detected in 2021 was genetically distinct from those reported in 2018. The 2021 virus shared ancestry with CHIKV strains reported in India. This strain possessed E1-K211E, E2-V264A, and E1-I317V mutations. Novel substitutions were identified. The CHIKV re-emergence in 2021 in Jeddah belonged to the Indian subcontinent/Southeast Asia clade of ECSA. More molecular epidemiological information is needed to better understand and evaluate the prevalence of CHIKV in Saudi Arabia.

Understanding the Transmission Dynamics of the Chikungunya Virus in Africa

The Chikungunya virus (CHIKV) poses a significant global public health concern, especially in Africa. Since its first isolation in Tanzania in 1953, CHIKV has caused recurrent outbreaks, challenging healthcare systems in low-resource settings. Recent outbreaks in Africa highlight the dynamic nature of CHIKV transmission and the challenges of underreporting and underdiagnosis. Here, we review the literature and analyse publicly available cases, outbreaks, and genomic data, providing insights into the epidemiology, genetic diversity, and transmission dynamics of CHIKV in Africa. Our analyses reveal the circulation of geographically distinct CHIKV genotypes, with certain regions experiencing a disproportionate burden of disease. Phylogenetic analysis of sporadic outbreaks in West Africa suggests repeated emergence of the virus through enzootic spillover, which is markedly different from inferred transmission dynamics in East Africa, where the virus is often introduced from Asian outbreaks, including the recent reintroduction of the Indian Ocean lineage from the Indian subcontinent to East Africa. Furthermore, there is limited evidence of viral movement between these two regions. Understanding the history and transmission dynamics of outbreaks is crucial for effective public health planning. Despite advances in surveillance and research, diagnostic and surveillance challenges persist. This review and secondary analysis highlight the importance of ongoing surveillance, research, and collaboration to mitigate the burden of CHIKV in Africa and improve public health outcomes.

The evolutionary and molecular history of a chikungunya virus outbreak lineage

In 2018-2019, Thailand experienced a nationwide spread of chikungunya virus (CHIKV), with approximately 15,000 confirmed cases of disease reported. Here, we investigated the evolutionary and molecular history of the East/Central/South African (ECSA) genotype to determine the origins of the 2018-2019 CHIKV outbreak in Thailand. This was done using newly sequenced clinical samples from travellers returning to Sweden from Thailand in late 2018 and early 2019 and previously published genome sequences. Our phylogeographic analysis showed that before the outbreak in Thailand, the Indian Ocean lineage (IOL) found within the ESCA, had evolved and circulated in East Africa, South Asia, and Southeast Asia for about 15 years. In the first half of 2017, an introduction occurred into Thailand from another South Asian country, most likely Bangladesh, which subsequently developed into a large outbreak in Thailand with export to neighbouring countries. Based on comparative phylogenetic analyses of the complete CHIKV genome and protein modelling, we identified several mutations in the E1/E2 spike complex, such as E1 K211E and E2 V264A, which are highly relevant as they may lead to changes in vector competence, transmission efficiency and pathogenicity of the virus. A number of mutations (E2 G205S, Nsp3 D372E, Nsp2 V793A), that emerged shortly before the outbreak of the virus in Thailand in 2018 may have altered antibody binding and recognition due to their position. This study not only improves our understanding of the factors contributing to the epidemic in Southeast Asia, but also has implications for the development of effective response strategies and the potential development of new vaccines.

Unraveling Dengue Virus Diversity in Asia: An Epidemiological Study through Genetic Sequences and Phylogenetic Analysis

Dengue virus (DENV) is the causative agent of dengue. Although most infected individuals are asymptomatic or present with only mild symptoms, severe manifestations could potentially devastate human populations in tropical and subtropical regions. In hyperendemic regions such as South Asia and Southeast Asia (SEA), all four DENV serotypes (DENV-1, DENV-2, DENV-3, and DENV-4) have been prevalent for several decades. Each DENV serotype is further divided into multiple genotypes, reflecting the extensive diversity of DENV. Historically, specific DENV genotypes were associated with particular geographical distributions within endemic regions. However, this epidemiological pattern has changed due to urbanization, globalization, and climate change. This review comprehensively traces the historical and recent genetic epidemiology of DENV in Asia from the first time DENV was identified in the 1950s to the present. We analyzed envelope sequences from a database covering 16 endemic countries across three distinct geographic regions in Asia. These countries included Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka from South Asia; Cambodia, Laos, Myanmar, Thailand, and Vietnam from Mainland SEA; and Indonesia, the Philippines, Malaysia, and Singapore from Maritime SEA. Additionally, we describe the phylogenetic relationships among DENV genotypes within each serotype, along with their geographic distribution, to enhance the understanding of DENV dynamics.

Isolation and molecular detection of dengue and chikungunya virus from field-collected adult mosquitoes in Kelantan, Malaysia

BACKGROUND OBJECTIVES

Dengue and chikungunya infections are one of the major health problems that have plagued the human population globally. All dengue virus (DENV) serotypes circulate within Malaysia with particular serotypes dominating in different years/outbreaks. In the state of Kelantan, an increasing number of DENV and chikungunya virus (CHIKV) new cases have been reported, including several deaths. This study aimed to isolate and detect these arboviruses from adult mosquitoes in Kelantan.

METHODS

Adult mo squito samples were collected from January to August 2019 and were identified according to gender, species and locality. The isolation of the virus was done in C6/36 cells. Dengue NS1 antigen was carried out using direct mosquito lysate and mosquito culture supernatant. Detection and serotyping of the DENV was performed using multiplex RT-PCR and CHIKV detection using a one-step RT-PCR assay.

RESULTS

Of 91 mosquito pools, four were positive for NS1 antigen comprising two pools (2.2%) of male Ae. albopictus (Pulau Melaka and Kubang Siput) and two pools (2.2%) of Ae. aegypti (Kampung Demit Sungai). DENV 1 was detected in one pool (0.9%) of female Ae. albopictus among 114 tested Aedes pools. Two pools of 114 pools (1.7%) from both male Aedes species were positive with double serotypes, DENV 1 and DENV 2 (Pulau Melaka). However, no pool was positive for CHIKV.

INTERPRETATION CONCLUSION

The presence of DENV and the main vectors of arboviruses in Kelantan are pertinent indicators of the need to improve vector controls to reduce arbovirus infections among people in the localities.

Chikungunya in Zhejiang Province, Southeast China

Background

Chikungunya is emerging and reemerging word-widely in the past decades. It is non-endemic in Zhejiang Province, Southeast China. Aedes albopictus, one of major vectors of chikungunya, is widely-distribution in Zhejiang, and autochthonous transmission is possible after introducing chikungunya virus.

Methods

Retrospectively collected the epidemiological, clinical and genetic data of chikungunya and conducted the descriptive analysis and gene sequence analysis.

Results

From 2008 to 2022, 29 chikungunya cases, including 26 overseas imported and 3 local cases, were reported and no cases died of chikungunya. More than half of the imported cases (53.85%) were from Southeast Asia. Seasonal peak of the imported cases was noted between August and September, and 42.31% cases onset in those 2 months. Eight prefecture-level cities and 16 counties reported cases during the study period, with Jinghua (27.59%) and Hangzhou (24.14%) reporting the largest number of cases. The 3 local cases were all reported in Qujiang, Quzhou in 2017. For imported cases, the male-female gender ratio was 2.71:1, 20-30 years old cases (46.15%) and commercial service (42.31%) accounted for the highest proportion. Clinically, fever (100%), fatigue (94.44%), arthralgia (79.17%), headache (71.43%) and erythra (65.22%) were the most common reported symptoms. Eight whole-genome sequences were obtained and belonged to East/Central/South African (ECSA) or Asian genotype.

Conclusions

With the change of immigration policy, the surveillance of chikungunya should be strengthened and the ability of the case discovery and diagnosis should be improved in Zhejiang in the post-COVID-19 era.

Insights into the structure, functional perspective, and pathogenesis of ZIKV: an updated review

Zika virus (ZIKV) poses a serious threat to the entire world. The rapid spread of ZIKV and recent outbreaks since 2007 have caused worldwide concern about the virus. Diagnosis is complicated because of the cross-reactivity of the virus with other viral antibodies. Currently, the virus is diagnosed by molecular techniques such as RT-PCR and IgM-linked enzyme immunoassays (MAC-ELISA). Recently, outbreaks and epidemics have been caused by ZIKV, and severe clinical symptoms and congenital malformations have also been associated with the virus. Although most ZIKV infections present with a subclinical or moderate flu-like course of illness, severe symptoms such as Guillain-Barre syndrome in adults and microcephaly in children of infected mothers have also been reported. Because there is no reliable cure for ZIKV and no vaccine is available, the public health response has focused primarily on preventing infection, particularly in pregnant women. A comprehensive approach is urgently needed to combat this infection and stop its spread and imminent threat. In view of this, this review aims to present the current structural and functional viewpoints, structure, etiology, clinical prognosis, and measures to prevent this transmission based on the literature and current knowledge. Moreover, we provide thorough description of the current understanding about ZIKV interaction with receptors, and a comparative examination of its similarities and differences with other viruses.

Coinfection and circulation of chikungunya virus and dengue virus in pediatric patients in Myanmar, 2019

Myanmar is an endemic country for arboviruses, and outbreaks occur frequently. A cross-sectional analytical study was conducted during the peak season of the chikungunya virus (CHIKV) outbreak in 2019. A total of 201 patients with acute febrile illness who were admitted to the 550-bedded Mandalay Children Hospital in Myanmar were enrolled in the study, and virus isolation, serological tests, and molecular tests for the dengue virus (DENV) and CHIKV were performed for all samples. Out of 201 patients, 71 (35.3%) were only DENV-infected, 30 (14.9%) were only CHIKV-infected and 59 (29.4%) were coinfected with DENV and CHIKV. The viremia levels of the DENV- and CHIKV- mono-infected groups were significantly higher than those of the group coinfected with DENV and CHIKV. Genotype I of DENV-1, genotypes I and III of DENV-3, genotype I of DENV-4 and the East/Central/South African genotype of CHIKV were co-circulating during the study period. Two novel epistatic mutations of CHIKV (E1:K211E and E2:V264A) were noted. This study highlighted that there were many coinfection cases during the outbreak and that the co-circulation of both viruses in DENV-endemic regions warrants effective monitoring of these emerging pathogens via comprehensive surveillance to facilitate the implementation of effective control measures.

The First Genomic Characterization of the Chikungunya Virus in Saudi Arabia

BACKGROUND

Chikungunya is an arboviral infection caused by the Chikungunya virus (CHIKV) transmitted to humans by mosquitoes of Aedes spp. CHIKV has been confined to African countries and South-East Asia up to 2004, but since then, the pathogen has become more global, and its high morbidity rate has become more visible. Saudi Arabia is not an endemic region of CHIKV, and the virus's origin is not yet fully understood. This study aimed to characterize the genome of CHIKV from samples detected in Jeddah in 2018.

METHOD

Twenty-two sets of primers were designed to amplify near-full length genome of CHIKV. RT-PCR was conducted from clinical samples. Two samples were used for studying near complete genome sequence while the remaining samples were used to study the E1 gene. Different bioinformatics tools were utilized.

RESULTS

Phylogenetic analysis showed that the CHIKV strains clustered with strains isolated from Kenya during 2017-2018 and belonged to ECSA genotype. E1: L136F, K211E and I317V mutations were identified in our strains. Also, E2: M74I, A76T, and V264A mutations were documented. Additionally, the capsid N79S substitution was also detected.

CONCLUSION

The genome of CHIKV was analyzed for the first time in Saudi Arabia to better understand the origin of the CHIKV and its genetic diversity, which showed high similarity with IE-a subclade of CHIKV strains detected in Mombasa (Kenya) indicating its possible origin.

Innate immune pathway modulator screen identifies STING pathway activation as a strategy to inhibit multiple families of arbo and respiratory viruses

RNA viruses continue to remain a threat for potential pandemics due to their rapid evolution. Potentiating host antiviral pathways to prevent or limit viral infections is a promising strategy. Thus, by testing a library of innate immune agonists targeting pathogen recognition receptors, we observe that Toll-like receptor 3 (TLR3), stimulator of interferon genes (STING), TLR8, and Dectin-1 ligands inhibit arboviruses, Chikungunya virus (CHIKV), West Nile virus, and Zika virus to varying degrees. STING agonists (cAIMP, diABZI, and 2',3'-cGAMP) and Dectin-1 agonist scleroglucan demonstrate the most potent, broad-spectrum antiviral function. Furthermore, STING agonists inhibit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and enterovirus-D68 (EV-D68) infection in cardiomyocytes. Transcriptome analysis reveals that cAIMP treatment rescue cells from CHIKV-induced dysregulation of cell repair, immune, and metabolic pathways. In addition, cAIMP provides protection against CHIKV in a chronic CHIKV-arthritis mouse model. Our study describes innate immune signaling circuits crucial for RNA virus replication and identifies broad-spectrum antivirals effective against multiple families of pandemic potential RNA viruses.

Broad-spectrum antiviral inhibitors targeting pandemic potential RNA viruses

RNA viruses continue to remain a clear and present threat for potential pandemics due to their rapid evolution. To mitigate their impact, we urgently require antiviral agents that can inhibit multiple families of disease-causing viruses, such as arthropod-borne and respiratory pathogens. Potentiating host antiviral pathways can prevent or limit viral infections before escalating into a major outbreak. Therefore, it is critical to identify broad-spectrum antiviral agents. We have tested a small library of innate immune agonists targeting pathogen recognition receptors, including TLRs, STING, NOD, Dectin and cytosolic DNA or RNA sensors. We observed that TLR3, STING, TLR8 and Dectin-1 ligands inhibited arboviruses, Chikungunya virus (CHIKV), West Nile virus (WNV) and Zika virus, to varying degrees. Cyclic dinucleotide (CDN) STING agonists, such as cAIMP, diABZI, and 2',3'-cGAMP, and Dectin-1 agonist scleroglucan, demonstrated the most potent, broad-spectrum antiviral function. Comparative transcriptome analysis revealed that CHIKV-infected cells had larger number of differentially expressed genes than of WNV and ZIKV. Furthermore, gene expression analysis showed that cAIMP treatment rescued cells from CHIKV-induced dysregulation of cell repair, immune, and metabolic pathways. In addition, cAIMP provided protection against CHIKV in a CHIKV-arthritis mouse model. Cardioprotective effects of synthetic STING ligands against CHIKV, WNV, SARS-CoV-2 and enterovirus D68 (EV-D68) infections were demonstrated using human cardiomyocytes. Interestingly, the direct-acting antiviral drug remdesivir, a nucleoside analogue, was not effective against CHIKV and WNV, but exhibited potent antiviral effects against SARS-CoV-2, RSV (respiratory syncytial virus), and EV-D68. Our study identifies broad-spectrum antivirals effective against multiple families of pandemic potential RNA viruses, which can be rapidly deployed to prevent or mitigate future pandemics.

Clinical and epidemiologic evaluation of a 2020 chikungunya outbreak in Cambodia

BACKGROUND

In 2020, the Kingdom of Cambodia experienced a nationwide outbreak of chikungunya virus (CHIKV). Despite an increase in the frequency of outbreaks and expanding geographic range of CHIKV, diagnostic challenges remain, and limited surveillance data of sufficient granularity are available to characterize epidemiological profiles and disease dynamics of the virus.

METHODS

An ongoing and long-standing cross-sectional study of acute undifferentiated febrile illness (AUFI) in Cambodia was leveraged to describe the disease epidemiology and characterize the clinical presentation of patients diagnosed with CHIKV during the 2020 outbreak. Participants presenting with AUFI symptoms at ten study locations provided acute and convalescent blood samples and were tested for CHIKV using a reverse transcription-polymerase chain reaction (RT-PCR) and serological diagnostic methods including IgM and IgG. Acute and follow-up clinical data were also collected.

RESULTS

From 1194 participant blood samples tested, 331 (27.7%) positive CHIKV cases were detected. Most CHIKV positive individuals (280, 84.6%) reported having a fever 3 to 4 days prior to visiting a health facility. Symptoms including chills, joint pain, nausea, vomiting, and lesions were all statistically significant among CHIKV positive participants compared to CHIKV negative AUFI participants. Cough was negatively associated with CHIKV positive participants. Positivity proportions were significantly higher among adults compared to children. No significant difference was found in positivity proportion between rainy and dry seasons during the outbreak. Positive CHIKV cases were detected in all study site provinces, with the highest test positivity proportion recorded in the rural northeast province of Kratie.

CONCLUSIONS

Surveillance data captured in this study provided a clinical and epidemiological characterization of positive CHIKV patients presenting at selected health facilities in Cambodia in 2020, and highlighted the widespread distribution of the outbreak, impacting both urban and rural locations. Findings also illustrated the importance of utilizing both RT-PCR and serological testing for effective CHIKV surveillance.

Virological, Serological and Clinical Analysis of Chikungunya Virus Infection in Thai Patients

From 2018 to 2020, the Chikungunya virus (CHIKV) outbreak re-emerged in Thailand with a record of more than 10,000 cases up until the end of 2020. Here, we studied acute CHIKV-infected patients who had presented to the Bangkok Hospital for Tropical Diseases from 2019 to 2020 by assessing the relationship between viral load, clinical features, and serological profile. The results from our study showed that viral load was significantly high in patients with fever, headache, and arthritis. We also determined the neutralizing antibody titer in response to the viral load in patients, and our data support the evidence that an effective neutralizing antibody response against the virus is important for control of the viral load. Moreover, the phylogenetic analysis revealed that the CHIKV strains we studied belonged to the East, Central, and Southern African (ECSA) genotype, of the Indian ocean lineage (IOL), and possessed E1-K211E and E1-I317V mutations. Thus, this study provides insight for a better understanding of CHIKV pathogenesis in acute infection, along with the genomic diversity of the current CHIKV strains circulating in Thailand.