Chikungunya Virus Infection Research Articles

Characterization and Involvement of Exosomes Originating from Chikungunya Virus-Infected Epithelial Cells in the Transmission of Infectious Viral Elements.

The Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that affects the world’s popula-tion with chikungunya disease. Adaptation of the viral life cycle to their host cells’ environment is a key step for establishing their infection and pathogenesis. Recently, the accumulating evidence advocates a principal role of extracellular vesicles (EVs), including exosomes, in both the infection and pathogenesis of infectious diseases. However, the participation of exosomes in CHIKV infec-tion and transmission is not well clarified. Here, we demonstrated that the CHIKV RNA and pro-teins were captured in exosomes, which were released by viral-infected epithelial cells. A viral genomic element in the isolated exosomes was infectious to naïve mammalian epithelial cells. The assay of particle size distribution and transmission electron microscopy (TEM) revealed CHIKV-derived exosomes with a size range from 50 to 250 nm. Treatments with RNase A, Triton X-100, and immunoglobulin G antibodies from CHIKV-positive patient plasma indicated that in-fectious viral elements are encompassed inside the exosomes. Interestingly, our viral plaque for-mation also exhibited that infectious viral elements might be securely transmitted to neighboring cells by a secreted exosomal pathway. Taken together, our recent findings emphasize the evidence for a complementary means of CHIKV infection and suggest the role of exosome-mediated CHIKV transmission.

Chikungunya Vaccine Candidates: Current Landscape and Future Prospects.

Chikungunya virus (CHIKV) is an alphavirus that has spread globally in the last twenty years. Although mortality is rather low, infection can result in debilitating arthralgia that can persist for years. Unfortunately, no treatments or preventive vaccines are currently licensed against CHIKV infections. However, a large range of promising preclinical and clinical vaccine candidates have been developed during recent years. This review will give an introduction into the biology of CHIKV and the immune responses that are induced by infection, and will summarize CHIKV vaccine development.

Ten sessions of transcranial direct current stimulation for chronic chikungunya arthralgia: study protocol for a randomised clinical trial

IntroductionThe chikungunya virus infection is still an epidemic in Brazil with an incidence of 59.4 cases per 100 000 in the Northeast region. More than 60% of the patients present...

High levels of cardiovascular biomarkers in fatal Chikungunya virus infection

Chikungunya virus (CHIKV) infection is an emerging arboviral disease that has spread geographically to many previously unaffected areas. Although severe cases of acute CHIKV infection have been documented, little is known about its pathogenesis. We aimed to determine the levels of cardiovascular biomarkers in fatal and non-fatal patients with acute CHIKV infection. This study included fatal and non-fatal patients with CHIKV reported to National System for Public Health Surveillance and laboratory-confirmed by the Colombian National Institute of Health. Each fatal patient was matched to 2 non-fatal patients for age (± 10 years). Blood samples were processed for cardiovascular biomarkers by multiplex immunoassays. Twenty-five cases of fatal CHIKV infection and 50 patients of non-fatal CHIKV infection were included. Nearly 20% of the population were under 10 years old and 52% were over 60. The median serum levels of endocan-1 (p = 0.000), creatine kinase MB isoenzyme (p = 0.000), oncostatin (p = 0.000), fatty-acid-binding protein 3 (p = 0.000) and fatty-acid-binding protein 4 (p = 0.000) were significantly higher in fatal CHIKV infection cases than in non-fatal patients. Troponin I tended to be higher in fatal CHIKV infection cases than in non-fatal CHIKV infection patients (p = 0.063). Among fatal patients, no significant differences were found in serum levels of cardiovascular biomarkers among younger (< 50 years-old) and older (≥ 50 years-old) patients. We found high serum levels of cardiovascular biomarkers in fatal CHIKV infection. These results promote the fact that endothelial and cardiac damage can occurs and may be significant factors related organ failure and death in these patients.

Vathasura Kudineer, an Andrographis based polyherbal formulation exhibits immunomodulation and inhibits chikungunya virus (CHIKV) under invitro conditions

Ethnopharmacological relevanceChikungunya disease (CHIKD) is caused by the alphavirus, chikungunya virus (CHIKV) and is characterized by acute fever and joint inflammation; the inflammation continues even after clearance of the virus from the system, persisting for several months to years. Currently, there are no modern medicines/vaccines available for its treatment and use of over-the-counter anti-inflammatory generic medicines to relieve symptoms is generally practiced. In India, Indian traditional medicines hold a lot of promise to treat this infection and are routinely used during outbreaks. Aim of the studyIn the present study, we characterized the phytochemical and physicochemical properties of aqueous and ethanol extracts of the Vathasura Kudineer (VSK), a Andrographis based Siddha polyherbal formulation. Additionally, we evaluated its immunomodulatory and antiviral potential using an in vitro system. Materials and methodsAqueous and ethanolic extracts of VSK were prepared and their physico and phytochemical properties were obtained by biochemical and biophysical assays, HPTLC and FTIR. The aqueous extracts of VSK and several of its ingredients were evaluated for their cytotoxicity in Vero cells and using the maximum non-toxic concentration (MNTC), were processed further for evaluating their ability to inhibit CHIKV infection in Vero cells. We performed the co-treatment assay with ethanol extract of VSK and several of its ingredients to assess the antiviral activity against chikungunya virus on Vero cells and through pre-treatment assay (anti-adhesive effect), co-incubation assay (virucidal effect) and post-treatment assay (post-entry effect) were evaluated. Further, we tested the aqueous extract of VSK along with some of its ingredients for their immunomodulatory properties. We performed antioxidant and anti-inflammatory assays using LPS-simulated RAW 264.7 cells. For antioxidant capacity of extracts, we performed extra-cellular ABTS radical scavenging activity and intra-cellular effects on ROS generation and SOD activity. We assessed the effect on most important inflammatory mediators like Nitric oxide (NO) and Prostaglandin E2 (PGE2) and pro-inflammatory cytokines like interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNFα). ResultsWe provided the fingerprint of the phytochemicals of both ethanol and aqueous extracts of VSK that can be used for identification. We observed that ethanol extract was able to inhibit CHIKV infection at MNTC with 48 h of treatment on Vero cells. Its ingredient VSKI-As (Anethum sowa) found to be most effective to show virucidal effect while VSKI-Cs (Clerodendrum serratum) and VSKI-Pn (Pipper nigrum) found to be effective in post-entry effect. VSK was able to show ABTS radical scavenging activity, reduce ROS generation, inhibit the inflammatory mediators (NO and PGE2) and pro-inflammatory cytokines (IL-1β and TNFα) production in LPS-stimulated RAW 264.7 cells. ConclusionsWe provided the evidence that VSK has both immunomodulatory as well as antiviral potential. It shows virucidal as well as post-entry effects on chikungunya virus. VSK can inhibit pro-inflammatory cytokines, IL-1β and TNFα production by suppressing the inflammatory mediators, NO and PGE2.

An evaluation of global Chikungunya clinical management guidelines: A systematic review.

SummaryBackgroundChikungunya virus (CHIKV) has expanded its geographical reach in recent decades and is an emerging global health threat. CHIKV can cause significant morbidity and lead to chronic, debilitating arthritis/arthralgia in up to 40% of infected individuals. Prevention, early identification, and clinical management are key for improving outcomes. The aim of this review is to evaluate the quality, availability, inclusivity, and scope of evidence-based clinical management guidelines (CMG) for CHIKV globally.MethodsWe conducted a systematic review. Six databases were searched from Jan 1, 1989, to 14 Oct 2021 and grey literature until Sept 16, 2021, for CHIKV guidelines providing supportive care and treatment recommendations. Quality was assessed using the appraisal of Guidelines for Research and Evaluation tool. Findings are presented in a narrative synthesis. PROSPERO registration: CRD42020167361.Findings28 CMGs were included; 54% (15/28) were produced more than 5 years ago, and most were of low-quality (median score 2 out of 7 (range 1–7)). There were variations in the CMGs’ guidance on the management of different at-risk populations, long-term sequelae, and the prevention of disease transmission. While 54% (15/28) of CMGs recommended hospitalisation for severe cases, only 39% (11/28) provided guidance for severe disease management. Further, 46% (13/28) advocated for steroids in the chronic phase, but 18% (5/28) advised against its use.InterpretationThere was a lack of high-quality CMGs that provided supportive care and treatment guidance, which may impact patient care and outcomes. It is essential that existing guidelines are updated and adapted to provide detailed evidence-based treatment guidelines for different at-risk populations. This study also highlights a need for more research into the management of the acute and chronic phases of CHIKV infection to inform evidence-based care.FundingThe UK Foreign, Commonwealth and Development Office, Wellcome Trust [215091/Z/18/Z] and the Bill & Melinda Gates Foundation [OPP1209135].

Structural insights into the inhibition of the nsP2 protease from Chikungunya virus by molecular modeling approaches.

Chikungunya virus (CHIKV) is the etiological agent of the Chikungunya fever which has spread worldwide. Clinically, this disease may lead to prolonged incapacitating joint pain that can compromise remarkably the patients' quality of life. However, there are no licensed vaccines or specific drugs to fight this infection yet, making the search for novel therapies an imperative need. In this scenario, the CHIKV nsP2 protease emerged as an attractive therapeutic target once this protein plays a pivotal role in viral replication and pathogenesis. Hence, we investigated the structural basis for the inhibition of this enzyme by using molecular docking and dynamics simulations. Compounds with inhibitory activities against CHIKV nsP2 protease determined experimentally were selected from the literature. Docking studies with a set of stereoisomers showed that trans isomers, but not cis ones, bound close to the catalytic dyad which may explain isomerism requirements to the enzyme's inhibition. Further, binding mode analyses of other known inhibitors revealed highly conserved contacts between inhibitors and enzyme residues like N1011, C1013, A1046, Y1079, N1082, W1084, L1205, and M1242. Molecular dynamics simulations reinforced the importance of some of these interactions and pointed to nonpolar interactions as the main forces for inhibitors' binding. Finally, we observed that true inhibitors exhibited lower structural fluctuation, higher ligand efficiency and did not induce significant changes in protein correlated motions. Collectively, our findings might allow discerning true inhibitors from false ones and can guide drug development efforts targeting the nsP2 protease to fight CHIKV infections in the future.

MRNA Vaccine Designing Using Chikungunya Virus E Glycoprotein through Immunoinformatics-Guided Approaches.

Chikungunya virus is an alphavirus transmitted by mosquitos that develops into chikungunya fever and joint pain in humans. This virus’ name originated from a Makonde term used to describe an illness that changes the joints and refers to the posture of afflicted patients who are affected by excruciating joint pain. There is currently no commercially available drug or vaccine for chikungunya virus infection and the treatment is performed by symptom reduction. Herein, we have developed a computationally constructed mRNA vaccine construct featuring envelope glycoprotein as the target molecule to aid in the treatment process. We have utilized the reverse vaccinology approach to determine epitopes that would generate adaptive immune reactions. The resulting T and B lymphocytes epitopes were screened by various immunoinformatic tools and a peptide vaccine construct was designed. It was validated by proceeding to docking and MD simulation studies. The following design was then back-translated in nucleotide sequence and codons were optimized according to the expression host system (H. sapiens). Various sequences, including 3′ and 5′ UTR regions, Kozak sequence, poly (A) tail, etc., were introduced into the sequence for the construction of the final mRNA vaccine construct. The secondary structure was generated for validation of the mRNA vaccine construct sequence. Additionally, in silico cloning was also performed to design a vector for proceeding towards in vitro experimentation. The proposed designed vaccine construct may proceed with experimental testing for further efficacy verification and the final development of a vaccine against chikungunya virus infection.

Annexin A1-FPR2/ALX Signaling Axis Regulates Acute Inflammation during Chikungunya Virus Infection.

Chikungunya (CHIKV) is an arthritogenic alphavirus that causes a self-limiting disease usually accompanied by joint pain and/or polyarthralgia with disabling characteristics. Immune responses developed during the acute phase of CHIKV infection determine the rate of disease progression and resolution. Annexin A1 (AnxA1) is involved in both initiating inflammation and preventing over-response, being essential for a balanced end of inflammation. In this study, we investigated the role of the AnxA1-FPR2/ALX pathway during CHIKV infection. Genetic deletion of AnxA1 or its receptor enhanced inflammatory responses driven by CHIKV. These knockout mice showed increased neutrophil accumulation and augmented tissue damage at the site of infection compared with control mice. Conversely, treatment of wild-type animals with the AnxA1 mimetic peptide (Ac2–26) reduced neutrophil accumulation, decreased local concentration of inflammatory mediators and diminished mechanical hypernociception and paw edema induced by CHIKV-infection. Alterations in viral load were mild both in genetic deletion or with treatment. Combined, our data suggest that the AnxA1-FPR2/ALX pathway is a potential therapeutic strategy to control CHIKV-induced acute inflammation and polyarthralgia.

A Systematic Survey on Fog and IoT Driven Healthcare: Open Challenges and Research Issues

Technological advancements have made it possible to monitor, diagnose, and treat patients remotely. The vital signs of patients can now be collected with the help of Internet of Things (IoT)-based wearable sensor devices and then uploaded on to a fog server for processing and access by physicians for recommending prescriptions and treating patients through the Internet of Medical Things (IoMT) devices. This research presents the outcome of a survey conducted on healthcare integrated with fog computing and IoT to help researchers understand the techniques, technologies and performance parameters. A comparison of existing research focusing on technologies, procedures, and findings has been presented to investigate several aspects of fog computing in healthcare IoT-based systems, such as increased temporal complexity, storage capacity, scalability, bandwidth, and latency. Additionally, strategies, tools, and sensors used in various diseases such as heart disease, chronic disease, chikungunya viral infection, blood pressure, body temperature, pulse rate, diabetes, and type 2 diabetes have been compared.

Pro-Inflammatory Profile of Children Exposed to Maternal Chikungunya Virus Infection during the Intrauterine Period: A One-Year Follow-Up Study.

Chikungunya virus (CHIKV) vertical transmission occurs due to maternal viremia in the prepartum. Clinical presentation in neonates can be varied; however, the consequences of intrauterine exposure on the immune response are unclear. Thus, we aimed to analyze inflammatory alterations in children exposed to maternal CHIKV infection. This is a cross-sectional study that included children exposed to maternal CHIKV infection (confirmed by RT-qPCR and/or IgM). Circulant immune mediators were analyzed by a multiplex assay. RESULTS: We included 33 children, with a mean age of 3 ± 2.9 months-old, and 19 (57.6%) were male. Only one child presented neurological alterations. CHIKV-exposed infants showed elevated levels of MIP-1α, MIP-1β, and CCL-2 (p < 0.05). Pro-inflammatory cytokines such as TNFα, IL-6, and IL-7 (p < 0.0001) were also increased. In addition, lower levels of PDGF-BB and GM-CSF were observed in the same group (p < 0.0001). Principal component (PC) analysis highlighted a distinction in the inflammatory profile between groups, where PC explained 56.6% of the alterations. Our findings suggest that maternal exposure to CHIKV can affect the circulating levels of pro-inflammatory cytokines during the infants’ first year of life. The long-term clinical consequences of these findings should be investigated.

Retrospective Genomic Surveillance of Chikungunya Transmission in Minas Gerais State, Southeast Brazil.

ABSTRACTBrazil accounted for a total number of 1,276,194 reported cases of chikungunya fever between 2014 and 2022. Additionally, since 2015, the country has experienced an increasing death toll, in which the Northeast and Southeast regions appear to report the worst scenarios. Although the CHIKV transmission dynamics have been studied in many parts of the country since its introduction in 2014, little is still known about chikungunya virus (CHIKV) transmission and genetic diversity in the state of Minas Gerais, located in southeast Brazil. Moreover, no studies have been published characterizing CHIKV genomic surveillance in this state. Thus, to retrospectively explore the CHIKV epidemic in Minas Gerais, we generated 40 genomes from clinical samples using Nanopore sequencing. Phylogenetic analysis indicated that multiple introductions of CHIKV occurred, likely from the northeastern Brazilian states, with the most recent common ancestral strain dating to early March 2016, which is in agreement with local epidemiological reports. Additionally, epidemiological data reveals a decline in the number of reported cases from 2017 to 2021, indicating that population immunity or changes in vector activity may have contributed to the decreasing waves of CHIKV infection. Together, our results shed light on the dispersion dynamics of CHIKV and show that infections decreased from March 2017 to January 2021 despite multiple introductions into Minas Gerais State. In conclusion, our study highlights the importance of combining genomic and epidemiological data in order to assist public health laboratories in monitoring and understanding the patterns and diversity of mosquito-borne viral epidemics.IMPORTANCE Arbovirus infections in Brazil, including chikungunya, dengue, yellow fever, and Zika, result in considerable morbidity and mortality and are pressing public health concerns. However, our understanding of these outbreaks is hampered by the limited availability of genomic data. In this study, we combine epidemiological analysis and portable genome sequencing to retrospectively describe the CHIKV epidemic in Minas Gerais between 2017 and 2021. Our results indicate that the East/Central/South African (ECSA) CHIKV lineage was introduced into Minas Gerais by three distinct events, likely from the North and Northeast regions of Brazil. Our study provides an understanding of how CHIKV initiates transmission in the region and illustrates that genomics in the field can augment traditional approaches to infectious disease surveillance and control.

Neurological Disease Associated with Chikungunya in Indonesia.

Chikungunya virus (CHIKV) is recognized but rarely considered as a cause of central nervous system infection in endemic areas. A total of 244 patients with acute meningoencephalitis in Indonesia were retrospectively tested to identify whether any CHIKV infection was associated with neurological manifestations, especially in provinces known for CHIKV endemicity. Cerebrospinal fluid (CSF) and blood specimens were tested using CHIKV-specific real-time reverse transcription polymerase chain reaction and IgM ELISA, alongside a panel of neurotropic viruses. We report four cases of suspected or confirmed CHIKV-associated neurological disease, including CHIKV RNA detection in CSF of one patient and in acute serum of another, and CHIKV IgM in CSF of three patients and in serum of a fourth. In conclusion, CHIKV should be considered as a cause of neurologic disease in endemic areas and especially during outbreaks, in addition to the more common arboviral diseases such as dengue and Japanese encephalitis viruses.

Chikungunya Immunopathology as It Presents in Different Organ Systems.

Chikungunya virus (CHIKV) is currently an urgent public health problem as high morbidity from the virus leaves populations with negative physical, social, and economic impacts. CHIKV has the potential to affect every organ of an individual, leaving patients with lifelong impairments which negatively affect their quality of life. In this review, we show the importance of CHIKV in research and public health by demonstrating the immunopathology of CHIKV as it presents in different organ systems. Papers used in this review were found on PubMed, using “chikungunya and [relevant organ system]”. There is a significant inflammatory response during CHIKV infection which affects several organ systems, such as the brain, heart, lungs, kidneys, skin, and joints, and the immune response to CHIKV in each organ system is unique. Whilst there is clinical evidence to suggest that serious complications can occur, there is ultimately a lack of understanding of how CHIKV can affect different organ systems. It is important for clinicians to understand the risks to their patients.

Construction and Evaluation of Recombinant Adenovirus Candidate Vaccines for Chikungunya Virus.

Chikungunya virus (CHIKV) is a mosquito-borne virus. The emergence of CHIKV infection has raised global concern, and there is a growing need to develop safe and effective vaccines. Here, adenovirus 5 was used as the vaccine vector to construct recombinant adenoviruses expressing CHIKV E2, E1, and E2-6K-E1, respectively. And then the immunogenicity and protective efficiency against CHIKV were evaluated in BALB/c mice. Compared to the ad-wt control group, all three vaccines elicited significant humoral and cellar immune responses. The levels of neutralizing antibodies in the rAd-CHIKV-E2-6K-E1 and rAd-CHIKV-E2 groups both reached 1:256, which were 3.2 times higher than those in the rAd-CHIKV-E1 group. Furthermore, the levels of lymphocyte proliferation in rAd-CHIKV-E2-6K-E1 group were the highest. Besides, the concentrations of IFN-γ and IL-4 in mice immunized with rAd-CHIKV-E2-6K-E1 were 1.37 and 1.20 times higher than those in ad-wt immunized mice, respectively. After the challenge, mice in the rAd-CHIKV-E2-6K-E1 and rAd-CHIKV-E2 groups lost 2% of their body weight compared with 5% in the ad-wt control group. And low viral loads were detected in the heart, kidney, and blood of mice immunized with rAd-CHIKV-E2-6K-E1 and rAd-CHIKV-E2 at 3–5 dpc, which decreased by 0.4–0.7 orders of magnitude compared with the ad-wt control. Overall, these data suggest that the recombinant adenovirus is a potential candidate vaccine against CHIKV.

CHIKV infection reprograms codon optimality to favor viral RNA translation by altering the tRNA epitranscriptome

Ample evidence indicates that codon usage bias regulates gene expression. How viruses, such as the emerging mosquito-borne Chikungunya virus (CHIKV), express their genomes at high levels despite an enrichment in rare codons remains a puzzling question. Using ribosome footprinting, we analyze translational changes that occur upon CHIKV infection. We show that CHIKV infection induces codon-specific reprogramming of the host translation machinery to favor the translation of viral RNA genomes over host mRNAs with an otherwise optimal codon usage. This reprogramming was mostly apparent at the endoplasmic reticulum, where CHIKV RNAs show high ribosome occupancy. Mechanistically, it involves CHIKV-induced overexpression of KIAA1456, an enzyme that modifies the wobble U34 position in the anticodon of tRNAs, which is required for proper decoding of codons that are highly enriched in CHIKV RNAs. Our findings demonstrate an unprecedented interplay of viruses with the host tRNA epitranscriptome to adapt the host translation machinery to viral production.

English

Since January, 2012, the Pacific region has faced a heavy burden of concurrent epidemics of dengue, chikungunya, and zika virus infections. In 2016, WHO developed a global response strategic framework to ensure that zika virus is a priority and accelerated area of public health research. This study conducted in Bouak&eacute; (C&ocirc;te d&#39;Ivoire) is part of this framework. The main objective was to assess the knowledge and attitudes of health workers working there on the zika virus disease in order to consider a better preparation and response to a possible epidemic in C&ocirc;te d&#39;Ivoire. Cross-sectional study covering the period from October 2016 to March 2017 was used here. The sampling was comprehensive and included interviews with 258 persons. Subjects were interviewed using a questionnaire edited and adapted from the CAP questionnaire developed by WHO in 2016. People with prior knowledge of the zika virus disease represented 66.3% of the health workers surveyed. Their level of knowledge was insufficient in 83.5% of cases. Their attitudes were good in 51.5% of cases. In the authors&rsquo; final model, the exercise structure which was adjusted to the level of education and the corporation significantly influenced health workers&#39; attitudes toward illness. Health workers in public settings appeared to have a better attitude compared to their private colleagues (adjusted OR = 4.88; CI: 2.37-10.03; p-value: 0.000). The zika virus disease has attracted the attention of the medical community during the 2014-2016 period. This attention, while mitigated by the West African Ebola virus epidemic, deserves to be highlighted. Key words: Health workers-C&ocirc;te d&rsquo;Ivoire-knowledge-attitudes-Zika.

In vitro antiviral activity of piperidine alkaloids from Senna spectabilis flowers on Chikungunya virus infection.

Chikungunya fever is an endemic disease caused by the Chikungunya virus (CHIKV). To date there is no antiviral treatment against this infection or licensed vaccine to prevent it. Our study aims to evaluate whether (-)-cassine (1) and (-)-spectaline (2), the main alkaloids of Senna spectabilis, display anti-CHIKV activity. Both compounds have been described to be biologically active against neglected tropical diseases, including malaria, leishmaniasis, and schistosomiasis, which emphasizes that these molecules could be repurposed for chikungunya fever treatment. The structures of the isolated compounds 1 and 2 were identified by NMR and HRESIMS analyses, and their antiviral activity against CHIKV was assessed by a dose-response assay employing BHK-21 cells and CHIKV-nanoluc, a recombinant virus carrying the nanoluciferase gene reporter. Compound 1 presented CC50 of 126.5µM and EC50 of 14.9µM, while compound 2 presented CC50 of 91.9µM and EC50 of 8.3µM. The calculated selectivity index (SI) was 8.5 for 1 and 11.3 for 2. The data presented herein show that compounds 1 and 2 have potential for being repurposed as anti-CHIKV drug. Our promising in vitro results encourage further in vitro and in vivo assays. This is the first description of the antiviral activity of compounds 1 and 2 against CHIKV infection, which can impact the development of antiviral drug candidates against chikungunya fever, which sometimes can be debilitating.

Effectiveness of CHIKV vaccine VLA1553 demonstrated by passive transfer of human sera.

Chikungunya virus (CHIKV) is a reemerging mosquito-borne alphavirus responsible for numerous outbreaks. Chikungunya can cause debilitating acute and chronic disease. Thus, the development of a safe and effective CHIKV vaccine is an urgent global health priority. This study evaluated the effectiveness of the live-attenuated CHIKV vaccine VLA1553 against WT CHIKV infection by using passive transfer of sera from vaccinated volunteers to nonhuman primates (NHP) subsequently exposed to WT CHIKV and established a serological surrogate of protection. We demonstrated that human VLA1553 sera transferred to NHPs conferred complete protection from CHIKV viremia and fever after challenge with homologous WT CHIKV. In addition, serum transfer protected animals from other CHIKV-associated clinical symptoms and from CHIKV persistence in tissue. Based on this passive transfer study, a 50% micro–plaque reduction neutralization test titer of ≥ 150 was determined as a surrogate of protection, which was supported by analysis of samples from a seroepidemiological study. In conclusion, considering the unfeasibility of an efficacy trial due to the unpredictability and explosive, rapidly moving nature of chikungunya outbreaks, the definition of a surrogate of protection for VLA1553 is an important step toward vaccine licensure to reduce the medical burden caused by chikungunya.

Multiple chikungunya virus introductions in Lao PDR from 2014 to 2020.

The first documented chikungunya virus (CHIKV) outbreak in Lao People’s Democratic Republic (Lao PDR) occurred in 2012–2013. Since then, several imported and a few autochthonous cases were identified by the national arbovirus surveillance network. The present study aimed to summarize the main genetic features of the CHIKV strains detected in Lao PDR between 2014 and 2020. Samples from Lao patients presenting symptoms compatible with a CHIKV infection were centralized in Vientiane Capital city for real-time RT-PCR screening. Molecular epidemiology was performed by sequencing the E2-6K-E1 region. From 2014 to 2020, two Asian lineage isolates (e.g. French Polynesia; Indonesia), one ECSA-IOL lineage isolate (e.g. Thailand) and one unclassified (e.g. Myanmar) were imported in Vientiane Capital city. Sequences from the autochthonous cases recorded in the Central and Southern parts of the country between July and September 2020 belonged to the ECSA-IOL lineage and clustered with CHIKV strains recently detected in neighboring countries. These results demonstrate the multiple CHIKV introductions in Lao PDR since 2014 and provide evidence for sporadic and time-limited circulation of CHIKV in the country. Even if the circulation of CHIKV seems to be geographically and temporally limited in Lao PDR, the development of international tourism and trade may cause future outbreaks of CHIKV in the country and at the regional level.