Changing patterns of chikungunya virus: re-emergence of a zoonotic arbovirus

Safety, immunogenicity, and effectiveness of chikungunya vaccines in pregnant persons, children, and adolescents: a protocol for a living systematic review and meta-analysis

BACKGROUND

Chikungunya virus significantly impacts public health, primarily affecting regions in Africa and the Americas (predominantly Latin America and the Caribbean). Despite the global spread of the virus and its clinical manifestations and complications in vulnerable populations such as children and pregnant persons, no widely available vaccine is currently available. With recent advancements in vaccine development, there is a need to systematically evaluate the emerging evidence on the safety, immunogenicity, and efficacy of chikungunya vaccine candidates. This protocol outlines a living systematic review designed to continuously assess the growing research on chikungunya vaccines, focusing on diverse populations, including children and pregnant persons. We aim to provide up-to-date evidence to inform public health decisions and vaccine recommendations as new data is available.

METHODS

Our objective is to carry out a living systematic review and meta-analysis through biweekly searches in medical databases and clinical trial registries, aiming to identify relevant chikungunya vaccines studies on pregnant individuals, children, and adolescents. Pairs of reviewers will independently screen studies, extract data, and assess the risk of bias. Clinical trials, quasi-experimental studies, and observational studies, including case reports, will be considered for inclusion. Main outcomes will include the safety, efficacy, and effectiveness of chikungunya vaccines in pregnant individuals (including neonatal outcomes), as well as in children and adolescents. Reactogenicity and immunogenicity will be considered as secondary outcomes. Paired meta-analyses, incorporating predefined subgroup and sensitivity analyses, will be performed. Evidence certainty will be assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

DISCUSSION

This living systematic review and meta-analysis will continuously assess the safety, immunogenicity, and effectiveness of chikungunya vaccines in pregnant persons, children, and adolescents. Given the significant disease burden and potential complications in these populations, synthesizing emerging evidence is crucial for guiding immunization policies and clinical recommendations. By maintaining an updated analysis, this review will provide timely insights for public health agencies, researchers, and clinicians involved in vaccine implementation and maternal-child health.

STUDY REGISTRATION

Two protocols were registered in the International Prospective Register of Systematic Reviews database, CRD42024514513 and CRD42024516754.

Repurposing Efavirenz, the HIV Antiretroviral Drug for Chikungunya Virus Infection

Chikungunya virus (CHIKV) has frequently recurred in recent decades, causing outbreaks worldwide in tropical and subtropical regions. The re-emergence of CHIKV poses a substantial risk to human health, as no efficacious drugs are currently available to curb new outbreaks. Here, the anti-CHIKV activity of efavirenz was investigated by in vitro cell culture-based antiviral assays in different relevant cell lines. Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI) used for the treatment of acquired immunodeficiency syndrome (AIDS), and it has good oral bioavailability, long half-life, and affordable low cost. This study demonstrated dose-dependent robust anti-CHIKV activity of efavirenz at low micromolar concentration in two different cell lines with 50% effective concentration (EC50) of 1.1 to 1.3 μM. Interestingly, efavirenz also inhibited the replication of Sindbis virus (SINV) at a low micromolar range indicating potential broad anti-alphavirus activity. Time of addition assay, direct transfection of virus replicon RNA, and minus-sense-specific reverse transcription polymerase chain reaction (RT-PCR) elucidated that efavirenz hinders the viral replication at an early stage after the virus entry by inhibiting the viral RNA synthesis. Further, the binding affinity of efavirenz toward purified capsid protein (CP) was observed, suggesting that CP could be one of the antiviral targets for efavirenz in addition to viral or host proteins involved in viral RNA replication. Finally, the in vivo efficacy of efavirenz was assessed in a murine model and a decrease in CHIKV viral load was observed. In summary, the present study underscores the potential of repurposing efavirenz for antiviral therapy against CHIKV to curb future viral outbreaks.

Phylogenetic Analysis of Chikungunya Virus Eastern/Central/South African-Indian Ocean Epidemic Strains, 2004-2019

CHIKV infection is transmitted by Aedes mosquitoes spp., with Ae. aegypti considered as the primary vector and Ae. Albopictus playing an important role in sustaining outbreaks in Europe. The ECSA-Indian Ocean Lineage (IOL) strain emerged in Reunion, subsequently spreading to areas such as India, the Indian Ocean, and Southeast Asia, also causing outbreaks in naive countries, including more temperate regions, which originated from infected travelers. In Italy, two authocthounous outbreaks occurred in 2007 (Emilia Romagna region) and 2017 (Lazio and Calabria regions), caused by two different ECSA-IOL strains. The phylogenetics, evolution, and phylogeography of ECSA-IOL-CHIKV strains causing the 2007 and 2017 outbreaks in Italy were investigated. The mean evolutionary rate and time-scaled phylogeny were performed through BEAST. Specific adaptive vector mutations or key signature substitutions were also investigated. The estimated mean value of the CHIKV E1 evolutionary rate was 1.313 × 10-3 substitution/site/year (95% HPD: 8.709 × 10-4-1.827 × 10-3). The 2017 CHIKV Italian sequences of the outbreak in Lazio and of the secondary outbreak in Calabria were located inside a sub-clade dating back to 2015 (95% HPD: 2014-2015), showing an origin in India. Continued genomic surveillance combined with phylogeographic analysis could be useful in public health, as a starting point for future risk assessment models and early warning.

Next-Generation Point-of-Care Diagnostics: Silver Nanoparticle-Enhanced 3D-Printed Multiplex Electrochemical Biosensor for Detecting Dengue and Chikungunya Viruses

In recent years, the increasing prevalence of viral infections such as dengue (DENV) and chikungunya (CHIKV) has emphasized the vital need for new diagnostic techniques that are not only quick and inexpensive but also suitable for point-of-care and home usage. Existing diagnostic procedures, while useful, sometimes have limits in terms of speed, mobility, and price, particularly in resource-constrained environments and during epidemics. To address these issues, this study proposes a novel technique that combines 3D printing technology with electrochemical biosensors to provide a highly sensitive, user-friendly, and customizable diagnostic platform. This study focuses on a unique 3D-printed electrode cassette made with fused deposition modeling technology, which ensures strong structural alignment and improved performance under a variety of environmental conditions. When combined with paper-based electrodes loaded with silver nanoparticles, the platform dramatically enhances the detection sensitivity and reliability. The biosensor uses cyclic voltammetry and electrochemical impedance spectroscopy to detect DENV and CHIKV antigens within a linear range of 1 × 102 to 1 × 106 ng/mL. Results were delivered in 20 s and stable for 30 days. The device's performance was verified by testing with blood serum samples containing both DENV and CHIKV antigens, demonstrating its capacity to properly identify coinfections. This novel diagnostic tool represents a huge step forward in accessible and efficient healthcare solutions, bridging important gaps in the global battle against arboviral infections.

Design of therapeutic siRNAs for potential application to infection with chikungunya virus

Emergence of the Chikungunya virus (CHIKV) is a new threat in the world. The disastrous effect of this virus and the unavailability of specific drugs complicated the control and management of the disease. The development of a siRNA-based drug using multiple computational tools could be a way out as one of its therapeutics. Currently, very few siRNAs against CHIKV have been computationally designed and published. Here, we considered various parts of the CHIKV genome encoding different essential protein-coding genes for designing siRNAs with a view to silencing them, thereby rendering the virus inactive. Seven potential primary siRNAs were constructed, of which, five are hereafter recommended to be used as a therapeutic tool against the virus.

Assessment of heat-killed E. coli expressing Chikungunya virus E2 protein as a candidate vaccine for dual protection against Chikungunya virus and E. coli

The Chikungunya virus (CHIKV) is a mosquito-borne virus with a long history of recurring epidemics transmitted through Aedes mosquitoes. The rapid spread of CHIKV has intensified the need for potent vaccines. Escherichia coli (E.coli), a vital part of human gut microbiota, is utilized in recombinant DNA technology for cloning. However, its high adaptability can lead to severe infections in humans. This study aimed to develop the candidate dual vaccine against CHIKV and E. coli. For this, we expressed the CHIKV E2 protein in the E. coli Rosetta Bl21 cells and the protein expression was confirmed by western blotting. The IgG immune response of the candidate vaccine was determined against CHIKV and E. coli by ELISA. Further, the potential of antibodies to neutralize CHIKV was evaluated via Tissue Culture Infectious Dose 50 (TCID50). We observed that cells expressing E2 protein with alum immunized mice serum showed a five-fold higher IgG immune response against CHIKV, compared to control cells. The CHIKV neutralization assay results showed a two-fold decrease in CHIKV TCID50 value after 12 hours and a three-fold reduction after 120 hours. Similarly, the vaccine formulation also elicited a significantly higher IgG immune response against E. coli. The results suggested that expressing CHIKV E2 protein in E. coli is a potential approach for generating an IgG immune response against CHIKV and E. coli both. This study proposes a faster, safer, and cost-effective recombinant protein-based vaccine development.

Spatial-temporal distribution of chikungunya virus in Brazil: a review on the circulating viral genotypes and Aedes (Stegomyia) albopictus as a potential vector

Chikungunya virus (CHIKV) is mainly transmitted by the invasive mosquito Aedes (Stegomyia) aegypti in tropical and subtropical regions worldwide. However, genetic adaptations of the virus to the peri domestic mosquito vector Aedes (Stegomyia) albopictus has resulted in enhanced vector competence and associated epidemics and may contribute to further geographic expansion of CHIKV. However, evidence-based data on the relative role of Ae. albopictus in CHIKV transmission dynamics are scarce, especially in regions where Ae. aegypti is the main vector, such as in Brazil. Here, we review the CHIKV genotypes circulating in Brazil, spatial and temporal distribution of Chikungunya cases in Brazil, and susceptibility to infection and transmission (i.e., vector competence) of Ae. albopictus for CHIKV to better understand its relative contribution to the virus transmission dynamics.

Beyond the Bite: Detailed findings on Chikungunya and Dengue co-detection in Punjab, North India - clinical insights and diagnostic challenges

OBJECTIVES

The co-circulation of Chikungunya virus (CHIKV) and Dengue virus (DENV) in India poses a challenge for the diagnosing clinician, as they share similar clinical signs and symptoms and geographical distribution. Both arthropod-borne viruses are maintained in the environment by the Aedes mosquito, commonly found in tropical countries including India. Here we aim to investigate the clinical and laboratory aspects of Chikungunya/Dengue suspected cases in Punjab, India during 2021-2022, focusing on the differential diagnosis of Dengue.

METHODS

All suspected cases were submitted to serological differential diagnosis approaches to arboviruses like Chikungunya and Dengue. For the detection of Chikungunya Infection, CHIK IgM Capture ELISA was employed. Whereas, for Dengue NS1 antigen ELISA and IgM Capture ELISA assays were employed.

RESULTS

A total of 370 cases suspected of arboviral infection were investigated and 38.3% (142/370) were confirmed as Chikungunya. Chikungunya cases were slightly more prevalent in males (54%) and the most frequently affected age group was adults between 16 and 30 years old (45.7%). Polyarthralgia affected 79.5% of patients, 63.3% exhibited headache and 50% presented with retro-orbital pain. 28.9% (107/370) had serological evidence of DENV exposure by detection of specific anti-DENV IgM or NS1 and 9.1% (34/370) cases of co-detection of Chikungunya and Dengue were reported. Urban populations had a higher infection rate of co-detection of Chikungunya and Dengue than rural populations with 83% versus 17%, respectively.

CONCLUSIONS

Despite an initial clinical diagnosis of Dengue, most patients with fever and arthralgia were serologically confirmed as Chikungunya cases, with a notable prevalence of CHIKV/DENV co-detection. Strengthening differential diagnosis of circulating arboviruses is crucial for improving patient care and enhancing vector control and environmental management strategies.

Innovative strategies and challenges mosquito-borne disease control amidst climate change

The revival of the transmission dynamics of mosquito-borne diseases grants striking challenges to public health intensified by climate change worldwide. This inclusive review article examines multidimensional strategies and challenges linked to climate change and the epidemiology of mosquito-borne diseases such as malaria, dengue, Zika, chikungunya, and yellow fever. It delves into how the biology, pathogenic dynamics, and vector distribution of mosquitoes are influenced by continuously rising temperatures, modified rainfall patterns, and extreme climatic conditions. We also highlighted the high likelihood of malaria in Africa, dengue in Southeast Asia, and blowout of Aedes in North America and Europe. Modern predictive tools and developments in surveillance, including molecular gears, Geographic Information Systems (GIS), and remote sensing have boosted our capacity to predict epidemics. Integrated data management techniques and models based on climatic conditions provide a valuable understanding of public health planning. Based on recent data and expert ideas, the objective of this review is to provide a thoughtful understanding of existing landscape and upcoming directions in the control of mosquito-borne diseases regarding changing climate. This review determines emerging challenges and innovative vector control strategies in the changing climatic conditions to ensure public health.

Outbreak of Chikungunya Fever in the Central Valley of Chiapas, Mexico

Chikungunya virus (CHIKV) was isolated from humans in an outbreak of a febrile illness during July and August 2015 in the central valleys of Chiapas, Mexico. Sera obtained from 80 patients were tested for CHIKV RNA by reverse transcriptase polymerase chain reaction (RT-PCR) and for IgM and IgG antibodies by an enzyme linked immunoassay and a commercial indirect immunofluorescence test for CHIKV and dengue virus (DENV). Of the 80 patients, 67 were positive, including 50 for RNA and 17 for IgM. In addition, one patient was coinfected with CHIKV-DENV and 40 patients were positive for IgG antibody to DENV. The clinical manifestations included a high fever, polyarthralgia, headache, myalgia, rash, digestive disorders, conjunctivitis, and adenopathy associated with cervical and axillary inguinal regions. Complete nucleotide sequences of two of the CHIKV isolates showed that they belonged to the Asian lineage but did not group with other Mexican CHIKV isolates from the Chiapas coast. Our findings documented that different Asian lineage strains of CHIKV were circulating simultaneously during the 2015 outbreak in the Central Valley of Chiapas, Mexico. The 2024 cases suggest an explosive scenario of re-emergence of thousands of new Chikungunya and dengue fever (DENF) cases associated with deaths, and a dangerous increase of the four DENV serotypes throughout the Americas, especially in South American countries that have shown a high influx of human migration to southern Mexico. In Mexico, the state of Chiapas and other southern regions are the most vulnerable.

Systemic and Ophthalmic Manifestations of Chikungunya Fever

PURPOSE

Chikungunya is a re-emerging viral infection across the globe. The purpose of this article is to review the systemic and ophthalmic manifestations associated with chikungunya fever.

METHOD

A review of literature was conducted using online databases.

RESULTS

In this report, we have reviewed the presently available literature on uveitis caused by chikungunya and highlighted the current knowledge of its clinical manifestations, imaging features, laboratory diagnostics, and the available therapeutic modalities from the systemic and ophthalmic standpoint.

CONCLUSIONS

Ocular involvement in chikungunya infection may occur at the time of systemic manifestations or it may occur as a delayed presentation many weeks after the fever. Treatment relies on a supportive therapy for systemic illness. Treatment of ocular manifestation depends on the type of manifestations and usually includes a combination of topical and oral steroids.

High seroprevalence of IgM antibodies against chikungunya among patients with acute febrile illness seeking healthcare in a malaria-endemic area in the Afar Region, Northeast Ethiopia

Objective

Chikungunya is a disease caused by Aedes mosquito-borne chikungunya virus infection. This disease is becoming one of the emerging/re-emerging viral diseases in tropical and subtropical countries but is neglected by public health systems. This study assessed the seroprevalence of chikungunya virus infection among patients with acute febrile illness seeking healthcare in a malaria-endemic area in the Afar Region, Northeast Ethiopia.

Methods

An institution-based cross-sectional study was employed from September 2022 to March 2023 to assess the seroprevalence of chikungunya virus infection among malaria-suspected febrile patients attending health institutes in the Afar Region. Sociodemographic, clinical features, and venous blood were collected from each study participant. Blood films were prepared and examined for plasmodium infection using microscopy. Sera were separated and screened for anti-chikungunya virus IgM and IgG antibodies using an enzyme-linked immunosorbent assay. Data were entered into Epi Data 3.1 and analyzed using Stata/SE 14.2.

Results

In this study, 368 malaria-suspected febrile patients (55.4% female, aged 5-80 years old, mean ± SD = 27.28 ± 14.0) participated. The prevalence of anti-chikungunya virus IgM antibodies, indicating acute infection, was 47.8%, while the prevalence of IgG antibodies, indicating previous exposure, was 6.3%. Nonmarried participants were found to be more likely to have acute chikungunya virus infection (AOR = 2.34, 95% CI: 1.141-4.964), and back pain was associated with higher likelihood of acute infection (AOR = 1.785; 95% CI: 1.078-2.954). About 10.6% of the participants tested positive for Plasmodium parasite infection, with P. falciparum (84.6%) being the most common, followed by P. vivax (10.3%) and mixed (5.1%) infections.

Conclusion

The study revealed a high seroprevalence of acute chikungunya virus infection among febrile patients in the Afar Region, highlighting the importance of regular screening for arbovirus infection in febrile patients to control and mitigate chikungunya spread.

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 Mechanism of Action of L-Tyrosine Derivatives against Chikungunya Virus Infection In Vitro Depends on Structural Changes

Although the disease caused by chikungunya virus (CHIKV) is of great interest to public health organizations around the world, there are still no authorized antivirals for its treatment. Previously, dihalogenated anti-CHIKV compounds derived from L-tyrosine (dH-Y) were identified as being effective against in vitro infection by this virus, so the objective of this study was to determine the mechanisms of its antiviral action. Six dH-Y compounds (C1 to C6) dihalogenated with bromine or chlorine and modified in their amino groups were evaluated by different in vitro antiviral strategies and in silico tools. When the cells were exposed before infection, all compounds decreased the expression of viral proteins; only C4, C5 and C6 inhibited the genome; and C1, C2 and C3 inhibited infectious viral particles (IVPs). Furthermore, C1 and C3 reduce adhesion, while C2 and C3 reduce internalization, which could be related to the in silico interaction with the fusion peptide of the E1 viral protein. Only C3, C4, C5 and C6 inhibited IVPs when the cells were exposed after infection, and their effect occurred in late stages after viral translation and replication, such as assembly, and not during budding. In summary, the structural changes of these compounds determine their mechanism of action. Additionally, C3 was the only compound that inhibited CHIKV infection at different stages of the replicative cycle, making it a compound of interest for conversion as a potential drug.

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.

Commonly Reported Mosquito-Borne Viruses in the United States: A Primer for Pharmacists

Mosquito-borne diseases are a public health concern. Pharmacists are often a patient's first stop for health information and may be asked questions regarding transmission, symptoms, and treatment of mosquito borne viruses (MBVs). The objective of this paper is to review transmission, geographic location, symptoms, diagnosis and treatment of MBVs. We discuss the following viruses with cases in the US in recent years: Dengue, West Nile, Chikungunya, LaCrosse Encephalitis, Eastern Equine Encephalitis Virus, and Zika. Prevention, including vaccines, and the impact of climate change are also discussed.

Possible vertical transmission of Chikungunya virus infection detected in the cord blood samples from a birth cohort in Vietnam

BACKGROUND

Chikungunya virus (CHIKV) is an alphavirus (genus Alphavirus, family Togaviridae) that is primarily transmitted to humans by Aedes mosquitoes, and can be transmitted from mother to child. Little is known about CHIKV transmission in Vietnam, where dengue is endemic and Aedes mosquitoes are abundant. This study aimed to determine the prevalence and characteristics of vertical CHIKV infection in a birth cohort, and seroprevalence of anti-CHIKV antibodies with or without confirmation by neutralization tests among women bearing children in Vietnam.

METHODS

We collected umbilical cord blood plasma samples from each newly delivered baby in Nha Trang, Central Vietnam, between July 2017 and September 2018. Samples were subjected to molecular assay (quantitative real-time RT-PCR) and serological tests (anti-CHIKV IgM capture and IgG indirect enzyme-linked immunosorbent assay, and neutralization tests).

RESULTS

Of the 2012 tested cord blood samples from newly delivered babies, the CHIKV viral genome was detected in 6 (0.3%) samples by RT-PCR, whereas, 15 samples (0.7%) were anti-CHIKV-IgM positive. Overall, 18 (0.9%, 95% CI: 0.6-1.5) samples, including three positives for both CHIKV IgM and viral genome on RT-PCR, were regarded as vertical transmission of CHIKV infection. Of the 2012 cord blood samples, 10 (0.5%, 95% CI: 0.2-0.9) were positive for both anti-CHIKV IgM and IgG. Twenty-nine (1.4%, 95% CI: 1.0-2.1) were seropositive for anti-CHIKV IgG while 26 (1.3%, 95% CI: 0.8-1.9) of them were also positive for neutralizing antibodies, and regarded as seropositive with neutralization against CHIKV infection.

CONCLUSION

This is the first report of a possible CHIKV maternal-neonatal infection in a birth cohort in Vietnam. The findings indicate that follow-up and a differential diagnosis of CHIKV infection in pregnant women are needed to clarify the potential for CHIKV vertical transmission and its impact in the newborn.

Attenuation of neurovirulence of chikungunya virus by a single amino acid mutation in viral E2 envelope protein

BACKGROUND

Chikungunya virus (CHIKV) has reemerged as a major public health concern, causing chikungunya fever with increasing cases and neurological complications.

METHODS

In the present study, we investigated a low-passage human isolate of the East/ Central/South African (ECSA) lineage of CHIKV strain LK(EH)CH6708, which exhibited a mix of small and large viral plaques. The small and large plaque variants were isolated and designated as CHIKV-SP and CHIKV-BP, respectively. CHIKV-SP and CHIKV-BP were characterized in vitro and in vivo to compare their virus production and virulence. Additionally, whole viral genome analysis and reverse genetics were employed to identify genomic virulence factors.

RESULTS

CHIKV-SP demonstrated lower virus production in mammalian cells and attenuated virulence in a murine model. On the other hand, CHIKV-BP induced higher pro-inflammatory cytokine levels, compromised the integrity of the blood-brain barrier, and led to astrocyte infection in mouse brains. Furthermore, the CHIKV-SP variant had limited transmission potential in Aedes albopictus mosquitoes, likely due to restricted dissemination. Whole viral genome analysis revealed multiple genetic mutations in the CHIKV-SP variant, including a Glycine (G) to Arginine (R) mutation at position 55 in the viral E2 glycoprotein. Reverse genetics experiments confirmed that the E2-G55R mutation alone was sufficient to reduce virus production in vitro and virulence in mice.

CONCLUSIONS

These findings highlight the attenuating effects of the E2-G55R mutation on CHIKV pathogenicity and neurovirulence and emphasize the importance of monitoring this mutation in natural infections.

Novel strains of Culex flavivirus and Hubei chryso-like virus 1 from the Anopheles mosquito in western Kenya

Surveillance of mosquito vectors is critical for early detection, prevention and control of vector borne diseases. In this study we used advanced molecular tools, such as DNA barcoding in combination with novel sequencing technologies to discover new and already known viruses in genetically identified mosquito species. Mosquitoes were captured using BG sentinel traps in Western Kenya during May and July 2019, and homogenized individually before pooled into groups of ten mosquitoes. The pools and individual samples were then used for molecular analysis and to infect cell cultures. Of a total of fifty-four (54) 10-pools, thirteen (13) showed cytopathic effect (CPE) on VeroB4 cells, eighteen (18) showed CPE on C6/36 cells. Eight (8) 10-pools out of the 31 CPE positive pools showed CPE on both VeroB4 and C6/36 cells. When using reverse transcriptase polymerase chain reaction (RT-PCR), Sanger sequencing and Twist Comprehensive Viral Research Panel (CVRP) (Twist Biosciences), all pools were found negative by RT-PCR when using genus specific primers targeting alphaviruses, orthobunyaviruses and virus specific primers towards o'nyong-nyong virus, chikungunya virus and Sindbis virus (previously reported to circulate in the region). Interestingly, five pools were RT-PCR positive for flavivirus. Two of the RT-PCR positive pools showed CPE on both VeroB4 and C6/36 cells, two pools showed CPE on C6/36 cells alone and one pool on VeroB4 cells only. Fifty individual mosquito homogenates from the five RT-PCR positive 10-pools were analyzed further for flavivirus RNA. Of these, 19 out of the 50 individual mosquito homogenates indicated the presence of flavivirus RNA. Barcoding of the flavivirus positive mosquitoes revealed the mosquito species as Aedes aegypti (1), Mansonia uniformis (6), Anopheles spp (3), Culex pipiens (5), Culex spp (1), Coquilletidia metallica (2) and Culex quinquefasciatus (1). Of the 19 flavivirus positive individual mosquitoes, five (5) virus positive homogenates were sequenced. Genome sequences of two viruses were completed. One was identified as the single-stranded RNA Culex flavivirus and the other as the double-stranded RNA Hubei chryso-like virus 1. Both viruses were found in the same Anopheles spp. homogenate extracted from a sample that showed CPE on both VeroB4 and C6/36 cells. The detection of both viruses in a single mosquito homogenate indicated coinfection. Phylogenetic analyses suggested that the Culex flavivirus sequence detected was closely related to a Culex flavivirus isolated from Uganda in 2008. All four Hubei chryso-like virus 1 segments clusters closely to Hubei chryso-like virus 1 strains isolated in Australia, China and USA. Two novel strains of insect-specific viruses in Anopheles mosquitoes were detected and characterized.

High content screening strategies for large-scale compound libraries with a focus on high-containment viruses

A majority of viral diseases do not have FDA-approved drugs. The recent outbreaks caused by SARS-CoV-2, monkeypox, and Sudan ebolavirus have exposed the critical need for rapid screening and identification of antiviral compounds against emerging/re-emerging viral pathogens. A high-content screening (HCS) platform is becoming an essential part of the drug discovery process, thanks to developments in image acquisition and analysis. While HCS has several advantages, its full potential has not been realized in antiviral drug discovery compared to conventional drug screening approaches, such as fluorescence or luminescence-based microplate assays. Therefore, this review aims to summarize HCS workflow, strategies, and developments in image-based drug screening, focusing on high-containment viruses.

Integrated control strategies for dengue, Zika, and Chikungunya virus infections

Arboviruses are a major threat to public health in tropical regions, encompassing over 534 distinct species, with 134 capable of causing diseases in humans. These viruses are transmitted through arthropod vectors that cause symptoms such as fever, headache, joint pains, and rash, in addition to more serious cases that can lead to death. Among the arboviruses, dengue virus stands out as the most prevalent, annually affecting approximately 16.2 million individuals solely in the Americas. Furthermore, the re-emergence of the Zika virus and the recurrent outbreaks of chikungunya in Africa, Asia, Europe, and the Americas, with one million cases reported annually, underscore the urgency of addressing this public health challenge. In this manuscript we discuss the epidemiology, viral structure, pathogenicity and integrated control strategies to combat arboviruses, and the most used tools, such as vaccines, monoclonal antibodies, treatment, etc., in addition to presenting future perspectives for the control of arboviruses. Currently, specific medications for treating arbovirus infections are lacking, and symptom management remains the primary approach. However, promising advancements have been made in certain treatments, such as Chloroquine, Niclosamide, and Isatin derivatives, which have demonstrated notable antiviral properties against these arboviruses in vitro and in vivo experiments. Additionally, various strategies within vector control approaches have shown significant promise in reducing arbovirus transmission rates. These encompass public education initiatives, targeted insecticide applications, and innovative approaches like manipulating mosquito bacterial symbionts, such as Wolbachia. In conclusion, combatting the global threat of arbovirus diseases needs a comprehensive approach integrating antiviral research, vaccination, and vector control. The continued efforts of research communities, alongside collaborative partnerships with public health authorities, are imperative to effectively address and mitigate the impact of these arboviral infections on public health worldwide.

An overview of the role of Niemann-pick C1 (NPC1) in viral infections and inhibition of viral infections through NPC1 inhibitor

Viruses communicate with their hosts through interactions with proteins, lipids, and carbohydrate moieties on the plasma membrane (PM), often resulting in viral absorption via receptor-mediated endocytosis. Many viruses cannot multiply unless the host's cholesterol level remains steady. The large endo/lysosomal membrane protein (MP) Niemann-Pick C1 (NPC1), which is involved in cellular cholesterol transport, is a crucial intracellular receptor for viral infection. NPC1 is a ubiquitous housekeeping protein essential for the controlled cholesterol efflux from lysosomes. Its human absence results in Niemann-Pick type C disease, a deadly lysosomal storage disorder. NPC1 is a crucial viral receptor and an essential host component for filovirus entrance, infection, and pathogenesis. For filovirus entrance, NPC1's cellular function is unnecessary. Furthermore, blocking NPC1 limits the entry and replication of the African swine fever virus by disrupting cholesterol homeostasis. Cell entrance of quasi-enveloped variants of hepatitis A virus and hepatitis E virus has also been linked to NPC1. By controlling cholesterol levels, NPC1 is also necessary for the effective release of reovirus cores into the cytoplasm. Drugs that limit NPC1's activity are effective against several viruses, including SARS-CoV and Type I Feline Coronavirus (F-CoV). These findings reveal NPC1 as a potential therapeutic target for treating viral illnesses and demonstrate its significance for several viral infections. This article provides a synopsis of NPC1's function in viral infections and a review of NPC1 inhibitors that may be used to counteract viral infections. Video Abstract.

Evaluation of renal markers and liver enzymes in patients infected with the Chikungunya virus

Chikungunya virus (CHIKV) is an arbovirus (Togaviridae family, Alphavirus genus) that was first identified in 1953 in Tanzania. In 2014, the Asian and East/Central/South/African (ECSA) genotypes were identified in Brazil, although the genotype that spread the most in the following years across the Brazilian territory was the ECSA. The clinical symptoms associated with the infection caused by CHIKV include mainly fever, myalgia, headache, and arthralgia. In infections caused by other arboviruses (such as the ones caused by Dengue and West Nile viruses), changes in biochemical markers are often observed. This study aims to evaluate the biochemical markers profile of kidney and liver injury in acute patients infected with CHIKV. Two groups of correlations were found between the variables analyzed, namely, one between liver enzymes (r = 0.91), and another for kidney markers (r = 0.54-0.66). A significant elevation in the percentage of altered creatinine in CHIKV-infected patients was observed, followed by uric acid and AST. Altogether, in 8 different comparisons, it was possible to observe statistically significant differences between the levels of the markers when compared to the manifestation of symptoms (presence and absence). These noticeable changes in marker measurements could potentially be connected to the range of clinical symptoms seen in the disease.

Identifying Knowledge Gaps through the Systematic Review of Temperature-Driven Variability in the Competence of Aedes aegypti and Ae. albopictus for Chikungunya Virus

Temperature is a well-known effector of several transmission factors of mosquito-borne viruses, including within mosquito dynamics. These dynamics are often characterized by vector competence and the extrinsic incubation period (EIP). Vector competence is the intrinsic ability of a mosquito population to become infected with and transmit a virus, while EIP is the time it takes for the virus to reach the salivary glands and be expectorated following an infectious bloodmeal. Temperatures outside the optimal range act on life traits, decreasing transmission potential, while increasing temperature within the optimal range correlates to increasing vector competence and a decreased EIP. These relatively well-studied effects of other Aedes borne viruses (dengue and Zika) are used to make predictions about transmission efficiency, including the challenges presented by urban heat islands and climate change. However, the knowledge of temperature and chikungunya (CHIKV) dynamics within its two primary vectors-Ae. aegypti and Ae. albopictus-remains less characterized, even though CHIKV remains a virus of public-health importance. Here, we review the literature and summarize the state of the literature on CHIKV and temperature dependence of vector competence and EIP and use these data to demonstrate how the remaining knowledge gap might confound the ability to adequately predict and, thus, prepare for future outbreaks.

Zika, chikungunya and co-occurrence in Brazil: space-time clusters and associated environmental-socioeconomic factors

Chikungunya and Zika have been neglected as emerging diseases. This study aimed to analyze the space-time patterns of their occurrence and co-occurrence and their associated environmental and socioeconomic factors. Univariate (individually) and multivariate (co-occurrence) scans were analyzed for 608,388 and 162,992 cases of chikungunya and Zika, respectively. These occurred more frequently in the summer and autumn. The clusters with the highest risk were initially located in the northeast, dispersed to the central-west and coastal areas of São Paulo and Rio de Janeiro (2018-2021), and then increased in the northeast (2019-2021). Chikungunya and Zika demonstrated decreasing trends of 13% and 40%, respectively, whereas clusters showed an increasing trend of 85% and 57%, respectively. Clusters with a high co-occurrence risk have been identified in some regions of Brazil. High temperatures are associated with areas at a greater risk of these diseases. Chikungunya was associated with low precipitation levels, more urbanized environments, and places with greater social inequalities, whereas Zika was associated with high precipitation levels and low sewage network coverage. In conclusion, to optimize the surveillance and control of chikungunya and Zika, this study's results revealed high-risk areas with increasing trends and priority months and the role of socioeconomic and environmental factors.

Chikungunya virus virus-like particle vaccine is well tolerated and immunogenic in chikungunya seropositive individuals

In a phase 2 safety and immunogenicity study of a chikungunya virus virus-like particle (CHIKV VLP) vaccine in an endemic region, of 400 total participants, 78 were found to be focus reduction neutralizing antibody seropositive at vaccination despite being ELISA seronegative at screening, of which 39 received vaccine. This post hoc analysis compared safety and immunogenicity of CHIKV VLP vaccine in seropositive (n = 39) versus seronegative (n = 155) vaccine recipients for 72 weeks post-vaccination. There were no differences in solicited adverse events, except injection site swelling in 10.3% of seropositive versus 0.6% of seronegative recipients (p = 0.006). Baseline seropositive vaccine recipients had stronger post-vaccination luciferase neutralizing antibody responses versus seronegative recipients (peak geometric mean titer of 3594 and 1728, respectively) persisting for 72 weeks, with geometric mean fold increases of 3.1 and 13.2, respectively. In this small study, CHIKV VLP vaccine was well-tolerated and immunogenic in individuals with pre-existing immunity. ClinicalTrials.gov Identifier: NCT02562482.

Repurposing efavirenz, the HIV antiretroviral drug for Chikungunya virus infection.. [DOI: 10.1101/2023.09.29.560149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Chikungunya virus (CHIKV) has frequently recurred in recent decades, causing outbreaks worldwide in tropical and subtropical regions. The re-emergence of CHIKV poses a substantial risk to human health as no efficacious drugs are currently available to curb new outbreaks. Here, the anti-CHIKV activity of efavirenz was investigated byin vitrocell culture-based antiviral assay, immunofluorescence assay (IFA), and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI) used for treatment of acquired immunodeficiency syndrome (AIDS), and it has good oral bioavailability, long half-life and affordable low cost. This study demonstrated dose-dependent robust anti-CHIKV activity of efavirenz at low micromolar concentration (EC50= 1.33 µM). To determine potential broad anti-alphavirus activity of efavirenz, its inhibitory activity against Sindbis virus (SINV) was detected. Interestingly, efavirenz also inhibited the replication of SINV at a low micromolar range (EC50= 0.7 µM). Time of addition assay, direct transfection of virus replicon RNA and minus-sense specific RT-PCR elucidated that efavirenz hinders the viral replication at an early stage after the virus entry by inhibiting the viral RNA synthesis. Efavirenz showed a binding affinity with purified CHIKV capsid protein (CHIKV CP) and it is known that CHIKV CP plays a novel role in the early phase of viral protein synthesis, suggesting CP might be one of the potential protein targets in addition to viral or host proteins involved in viral genome replication. The present study underscores the repurposing of efavirenz for antiviral therapy against CHIKV to curb future viral outbreaks.

Highlights

Identification ofin vitroanti-CHIKV activity of efavirenz.

Efavirenz disrupts the early phase of virus replication by interfering in the CHIKV minus-sense RNA synthesis.

Efavirenz and tomatidine also inhibit SINV replication indicating potential broad spectrum anti-alphavirus activity.

Efavirenz holds potential as therapeutic treatment for clinical infections of Chikungunya.

The Innate Immune Response in DENV- and CHIKV-Infected Placentas and the Consequences for the Fetuses: A Minireview

Dengue virus (DENV) and chikungunya (CHIKV) are arthropod-borne viruses belonging to the Flaviviridae and Togaviridae families, respectively. Infection by both viruses can lead to a mild indistinct fever or even lead to more severe forms of the diseases, which are characterized by a generalized inflammatory state and multiorgan involvement. Infected mothers are considered a high-risk group due to their immunosuppressed state and the possibility of vertical transmission. Thereby, infection by arboviruses during pregnancy portrays a major public health concern, especially in countries where epidemics of both diseases are regular and public health policies are left aside. Placental involvement during both infections has been already described and the presence of either DENV or CHIKV has been observed in constituent cells of the placenta. In spite of that, there is little knowledge regarding the intrinsic earlier immunological mechanisms that are developed by placental cells in response to infection by both arboviruses. Here, we approach some of the current information available in the literature about the exacerbated presence of cells involved in the innate immune defense of the placenta during DENV and CHIKV infections.

Neglected tropical diseases in Republic of Guinea: disease endemicity, case burden and the road towards the 2030 target

Neglected tropical diseases (NTDs) predominantly affect vulnerable and marginalized populations in tropical and subtropical areas and globally affect more than one billion people. In Guinea, the burden of NTDs is estimated to be >7.5 disability-adjusted life years per million inhabitants. Currently the Guinea NTDs master plan (2017-2020) has identified eight diseases as public health problems: onchocerciasis, lymphatic filariasis, trachoma, schistosomiasis and soil-transmitted helminthiasis, leprosy, human African trypanosomiasis and Buruli ulcer. In this review we discuss the past and the current case burden of the priority NTDs in Guinea, highlight the major milestones and discuss current and future areas of focus for achieving the 2030 target outlined by the World Health Organization.

Investigating the etiology of acute febrile illness: a prospective clinic-based study in Uganda

BACKGROUND

Historically, malaria has been the predominant cause of acute febrile illness (AFI) in sub-Saharan Africa. However, during the last two decades, malaria incidence has declined due to concerted public health control efforts, including the widespread use of rapid diagnostic tests leading to increased recognition of non-malarial AFI etiologies. Our understanding of non-malarial AFI is limited due to lack of laboratory diagnostic capacity. We aimed to determine the etiology of AFI in three distinct regions of Uganda.

METHODS

A prospective clinic-based study that enrolled participants from April 2011 to January 2013 using standard diagnostic tests. Participant recruitment was from St. Paul's Health Centre (HC) IV, Ndejje HC IV, and Adumi HC IV in the western, central and northern regions, which differ by climate, environment, and population density. A Pearson's chi-square test was used to evaluate categorical variables, while a two-sample t-test and Krukalis-Wallis test were used for continuous variables.

RESULTS

Of the 1281 participants, 450 (35.1%), 382 (29.8%), and 449 (35.1%) were recruited from the western, central, and northern regions, respectively. The median age (range) was 18 (2-93) years; 717 (56%) of the participants were female. At least one AFI pathogen was identified in 1054 (82.3%) participants; one or more non-malarial AFI pathogens were identified in 894 (69.8%) participants. The non-malarial AFI pathogens identified were chikungunya virus, 716 (55.9%); Spotted Fever Group rickettsia (SFGR), 336 (26.2%) and Typhus Group rickettsia (TGR), 97 (7.6%); typhoid fever (TF), 74 (5.8%); West Nile virus, 7 (0.5%); dengue virus, 10 (0.8%) and leptospirosis, 2 (0.2%) cases. No cases of brucellosis were identified. Malaria was diagnosed either concurrently or alone in 404 (31.5%) and 160 (12.5%) participants, respectively. In 227 (17.7%) participants, no cause of infection was identified. There were statistically significant differences in the occurrence and distribution of TF, TGR and SFGR, with TF and TGR observed more frequently in the western region (p = 0.001; p < 0.001) while SFGR in the northern region (p < 0.001).

CONCLUSION

Malaria, arboviral infections, and rickettsioses are major causes of AFI in Uganda. Development of a Multiplexed Point-of-Care test would help identify the etiology of non-malarial AFI in regions with high AFI rates.

Bioinsecticidal activity of cajeput oil to pyrethroid-susceptible and -resistant mosquitoes

Mosquito-borne diseases are a significant threat to human health. The frequent and repetitive application of insecticides can result in the selection of resistant mosquito populations leading to product failures for reducing community disease transmission. It is important that new interventions are discovered and developed for reducing mosquito populations and, in turn, protecting human health. Plant essential oils are promising chemical interventions for reducing mosquito populations. The myrtle family, Myrtaceae, has numerous species to be studied as potential bioinsecticides. Here, we combined toxicological, biochemical, and neurophysiological approaches to provide evidence for cajeput oil and terpene constituents to elicit bioinsecticidal activity to pyrethroid-susceptible and -resistant Aedes aegypti. We show cajeput oil terpenes to enhance cAMP production, increase ACh levels, inhibit in vivo and in vitro AChE activity, and disrupt spike discharge frequencies of the mosquito CNS. This study presents the first report on the bioinsecticidal activity of cajeput oil terpenes to pyrethroid-susceptible and -resistant mosquitoes and provides comparative data for the octopaminergic system as a putative molecular target for the bioinsecticides with implications for resistance management.

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.

Effect of Viral Strain and Host Age on Clinical Disease and Viral Replication in Immunocompetent Mouse Models of Chikungunya Encephalomyelitis

The alphavirus chikungunya virus (CHIKV) represents a reemerging public health threat as mosquito vectors spread and viruses acquire advantageous mutations. Although primarily arthritogenic in nature, CHIKV can produce neurological disease with long-lasting sequelae that are difficult to study in humans. We therefore evaluated immunocompetent mouse strains/stocks for their susceptibility to intracranial infection with three different CHIKV strains, the East/Central/South African (ECSA) lineage strain SL15649 and Asian lineage strains AF15561 and SM2013. In CD-1 mice, neurovirulence was age- and CHIKV strain-specific, with SM2013 inducing less severe disease than SL15649 and AF15561. In 4-6-week-old C57BL/6J mice, SL15649 induced more severe disease and increased viral brain and spinal cord titers compared to Asian lineage strains, further indicating that neurological disease severity is CHIKV-strain-dependent. Proinflammatory cytokine gene expression and CD4+ T cell infiltration in the brain were also increased with SL15649 infection, suggesting that like other encephalitic alphaviruses and with CHIKV-induced arthritis, the immune response contributes to CHIKV-induced neurological disease. Finally, this study helps overcome a current barrier in the alphavirus field by identifying both 4-6-week-old CD-1 and C57BL/6J mice as immunocompetent, neurodevelopmentally appropriate mouse models that can be used to examine CHIKV neuropathogenesis and immunopathogenesis following direct brain infection.

Chikungunya fever

Chikungunya virus is widespread throughout the tropics, where it causes recurrent outbreaks of chikungunya fever. In recent years, outbreaks have afflicted populations in East and Central Africa, South America and Southeast Asia. The virus is transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Chikungunya fever is characterized by severe arthralgia and myalgia that can persist for years and have considerable detrimental effects on health, quality of life and economic productivity. The effects of climate change as well as increased globalization of commerce and travel have led to growth of the habitat of Aedes mosquitoes. As a result, increasing numbers of people will be at risk of chikungunya fever in the coming years. In the absence of specific antiviral treatments and with vaccines still in development, surveillance and vector control are essential to suppress re-emergence and epidemics.

Chikungunya: risks for travellers

RATIONALE FOR REVIEW

Chikungunya outbreaks continue to occur, with changing epidemiology. Awareness about chikungunya is low both among the at-risk travellers and healthcare professionals, which can result in underdiagnosis and underreporting. This review aims to improve awareness among healthcare professionals regarding the risks of chikungunya for travellers.

KEY FINDINGS

Chikungunya virus transmission to humans occurs mainly via daytime-active mosquitoes, Aedes aegypti and Aedes albopictus. The areas where these mosquitoes live is continuously expanding, partly due to climate changes. Chikungunya is characterized by an acute onset of fever with joint pain. These symptoms generally resolve within 1-3 weeks, but at least one-third of the patients suffer from debilitating rheumatologic symptoms for months to years. Large outbreaks in changing regions of the world since the turn of the 21st century (e.g. Caribbean, La Réunion; currently Brazil, India) have resulted in growing numbers of travellers importing chikungunya, mainly to Europe and North America. Viremic travellers with chikungunya infection have seeded chikungunya clusters (France, United States of America) and outbreaks (Italy in 2007 and 2017) in non-endemic countries where Ae. albopictus mosquitoes are present. Community preventive measures are important to prevent disease transmission by mosquitoes. Individual preventive options are limited to personal protection measures against mosquito bites, particularly the daytime-active mosquitos that transmit the chikungunya virus. Candidate vaccines are on the horizon and regulatory authorities will need to assess environmental and host risk factors for persistent sequelae, such as obesity, age (over 40 years) and history of arthritis or inflammatory rheumatologic disease to determine which populations should be targeted for these chikungunya vaccines.

CONCLUSIONS/RECOMMENDATIONS

Travellers planning to visit destinations with active CHIKV circulation should be advised about the risk for chikungunya, prevention strategies, the disease manifestations, possible chronic rheumatologic sequelae and, if symptomatic, seek medical evaluation and report potential exposures.

Growth in chikungunya virus-related research in ASEAN and South Asian countries from 1967 to 2022 following disease emergence: a bibliometric and graphical analysis

BACKGROUND

ASEAN (Association of Southeast Asian Nations) is composed of ten Southeast Asian countries bound by socio-cultural ties that promote regional peace and stability. South Asia, located in the southern subregion of Asia, includes nine countries sharing similarities in geographical and ethno-cultural factors. Chikungunya is one of the most significant problems in Southeast and South Asian countries. Much of the current chikungunya epidemic in Southeast Asia is caused by the emergence of a virus strain that originated in Africa and spread to Southeast Asia. Meanwhile, in South Asia, three confirmed lineages are in circulation. Given the positive correlation between research activity and the improvement of the clinical framework of biomedical research, this article aimed to examine the growth of chikungunya virus-related research in ASEAN and South Asian countries.

METHODS

The Scopus database was used for this bibliometric analysis. The retrieved publications were subjected to a number of analyses, including those for the most prolific countries, journals, authors, institutions, and articles. Co-occurrence mapping of terms and keywords was used to determine the current state, emerging topics, and future prospects of chikungunya virus-related research. Bibliometrix and VOSviewer were used to analyze the data and visualize the collaboration network mapping.

RESULTS

The Scopus search engine identified 1280 chikungunya-related documents published by ASEAN and South Asian countries between 1967 and 2022. According to our findings, India was the most productive country in South Asia, and Thailand was the most productive country in Southeast Asia. In the early stages of the study, researchers investigated the vectors and outbreaks of the chikungunya virus. In recent years, the development of antivirus agents has emerged as a prominent topic.

CONCLUSIONS

Our study is the first to present the growth of chikungunya virus-related research in ASEAN and South Asian countries from 1967 to 2022. In this study, the evaluation of the comprehensive profile of research on chikungunya can serve as a guide for future studies. In addition, a bibliometric analysis may serve as a resource for healthcare policymakers.

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.

Mosquitoes and Mosquito-Borne Diseases in Vietnam

Mosquito-borne diseases pose a significant threat to humans in almost every part of the world. Key factors such as global warming, climatic conditions, rapid urbanisation, frequent human relocation, and widespread deforestation significantly increase the number of mosquitoes and mosquito-borne diseases in Vietnam, and elsewhere around the world. In southeast Asia, and notably in Vietnam, national mosquito control programmes contribute to reducing the risk of mosquito-borne disease transmission, however, malaria and dengue remain a threat to public health. The aim of our review is to provide a complete checklist of all Vietnamese mosquitoes that have been recognised, as well as an overview of mosquito-borne diseases in Vietnam. A total of 281 mosquito species of 42 subgenera and 22 genera exist in Vietnam. Of those, Anopheles, Aedes, and Culex are found to be potential vectors for mosquito-borne diseases. Major mosquito-borne diseases in high-incidence areas of Vietnam include malaria, dengue, and Japanese encephalitis. This review may be useful to entomological researchers for future surveys of Vietnamese mosquitoes and to decision-makers responsible for vector control tactics.

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.

Updating the Insecticide Resistance Status of Aedes aegypti and Aedes albopictus in Asia: A Systematic Review and Meta-Analysis

Background: Aedes aegypti and Aedes albopictus are two important vectors of several important arboviruses, including the dengue, chikungunya, and Zika viruses. Insecticide application is an important approach to reduce vector abundance during Aedes spp.-borne outbreaks in the absence of effective vaccines and treatments. However, insecticide overuse can result in the development of resistance, and careful monitoring of resistance markers is required. Methods: This meta-analysis and systematic review explored the spatial and temporal patterns of insecticide resistance in Asia from 2000 to 2021. PubMed, Scopus, EbscoHost, and Embase were used to enhance the search capability. The random-effects model was applied for the 94 studies that met our inclusion criteria for qualitative synthesis and meta-analysis. Results: Four major insecticides were studied (malathion, dichlorodiphenyltrichloroethane, permethrin, and deltamethrin). Dichlorodiphenyltrichloroethane resistance rates were high in both Ae. aegypti and Ae. albopictus (68% and 64%, respectively). Conversely, malathion resistance was less prevalent in Ae. aegypti (3%), and deltamethrin resistance was less common in Ae. albopictus (2%). Ae. aegypti displayed consistently high resistance rates (35%) throughout the study period, whereas the rate of insecticide resistance in Ae. albopictus increased from 5% to 12%. The rates of the major kdr mutations F1534C, V1016G, and S989P were 29%, 26%, and 22%, respectively. Conclusions: Insecticide resistance in both Ae. aegypti and Ae. albopictus is widespread in Asia, although the rates vary by country. Continuous monitoring of the resistance markers and modification of the control strategies will be important for preventing unexpected outbreaks. This systematic review and meta-analysis provided up-to-date information on insecticide resistance in dengue-endemic countries in Asia.

A Retrospective Study of the Seroprevalence of Dengue Virus and Chikungunya Virus Exposures in Nigeria, 2010–2018

Arboviruses are important public health threats in many regions of the world. Nigeria has experienced outbreaks of arboviruses over the past decades, leading to concerns of widespread endemicity, which are frequently misdiagnosed. This study aimed to determine the seroprevalence of dengue virus (DENV) (a flavivirus) and chikungunya virus (CHIKV) (an alphavirus) infections in three major population centers of Nigeria. A convenience sample of 701 sera was collected from both healthy and febrile participants between August 2010 and March 2018. Sera were tested for prior exposure to CHIKV virus and DENV using indirect IgG ELISA. Results showed that 54.1% (379/701) of participants were seropositive for anti-DENV antibodies, 41.3% (290/701) were seropositive for anti-CHIKV antibodies, and 20.1% (141/701) had previous exposure to both. The seropositivity for prior CHIKV exposure and prior exposure to DENV and CHIKV was significantly associated with age (CHIKV: OR = 2.7 (95% CI: 1.7–4.3); DENV and CHIKV: OR = 2.2 (95% CI: 1.2–4.0) for adults compared to participants under 18 years old). Overall, the high seropositivity across all age groups suggests that arboviral infections are prevalent in Nigeria and indicates that surveillance and further epidemiological studies are required to determine the true burden of these infections and the spectrum of diseases associated with these exposures.

Development of Highly Sensitive Sandwich ELISA for the Early-Phase Diagnosis of Chikungunya Virus Utilizing rE2-E1 Protein

Introduction

Chikungunya is caused by an alpha virus transmitted to humans by an infected mosquito. Infection is generally considered to be self-limiting and non-critical. Chikungunya infection may be diagnosed by severe joint pain with fever, but it is difficult to diagnose because the symptoms of chikungunya are common to many pathogens, including dengue fever. Diagnosis mainly depends on viral culture, reverse transcriptase polymerase chain reaction (RT-PCR), and IgM ELISA. Early and accurate diagnosis of the virus can be achieved by the application of PCR methods, but the high cost and the need for a thermal cycler restrict the use of such methods. On the other hand, antibody-based IgM ELISA is considered to be inexpensive, but antibodies against chikungunya virus (CHIKV) only develop after 4 days of infection, so it has limited application in the earlier diagnosis of viral infection and the management of patients. Because of these challenges, a simple antigen-based sensitive, specific, and rapid detection method is required for the early and accurate clinical diagnosis of chikungunya.

Methods

The amino acid sequence of CHIKV ectodomain E1 and E2 proteins was analyzed using bioinformatics tools to determine the antigenic residues, particularly the B-cell epitopes and their characteristics. Recombinant E2-E1 CHIKV antigen was used for the development of polyclonal antibodies in hamsters and IgG was purified. Serological tests of 96 CHIKV patients were conducted by antigen-capture ELISA using primary antibodies raised against rCHIKV E2-E1 in hamsters and human anti-CHIKV antibodies.

Results

We observed high specificity and sensitivity, of 100% and 95.8%, respectively, and these values demonstrate the efficiency of the test as a clinical diagnostic tool. There was no cross-reactivity with samples taken from dengue patients.

Discussion

Our simple and sensitive sandwich ELISA for the early-phase detection of CHIKV infection may be used to improve the diagnosis of chikungunya.

A validated triplex RT-qPCR protocol to simultaneously detect chikungunya, dengue and Zika viruses in mosquitoes

BACKGROUND & OBJECTIVES

Recently, the incidences of chikungunya, dengue and Zika infections have increased due to globalization and urbanization. It is vital that reliable detection tools become available to assess the viral prevalence within mosquito populations.

METHODS

Based on the previous publications on clinical diagnosis in human infections, for the first time, we described a customized triplex RT-qPCR protocol for simultaneous detection of chikungunya virus (CHIKV), dengue virus serotypes 1-4 (DENV1-4) and Zika virus (ZIKV) in mosquitoes.

RESULTS

In preliminary assessment to determine the specificity and sensitivity of primers and probes, all six targets were detected individually with the following thresholds as indicated by calculated pfu equivalents: 3.96x10⁰ for CHIKV, 3.80x10¹ for DENV1, 3.20x10¹ for DENV2, 8.00x10⁴ for DENV3, 1.58x10⁰ for DENV4, and 6.20x10⁰ for ZIKV When tested in a full combination of six targets (CDZ mix), CHIKV, DENV1-4 mix or ZIKV were all detected with the thresholds of 1.32x10⁰ for CHIKV, 3.79x10⁰ for DENV1-4 and 2.06x10⁰ for ZIKV All targets, individually or in full combination were detected in the mixtures of Aedes aegypti (L.) homogenate and viral lysates. A robust evaluation with three replicates in each of three plates for CHIKV, DENV1-4 and ZIKV individually or in full combination was conducted. In individual assays, CHIKV was detected to 3.96x10^-1, DENV1-4 to 1.14x10⁰ and ZIKV to 3.20x10⁰. In full combination assays, CHIKV was detected to 1.32x10⁴, DENV1-4 to 3.79x10¹ and ZIKV to 1.07x10⁰.

INTERPRETATION & CONCLUSION

This triplex RT-qPCR assay appears to consistently detect all six targets and does not cross react with Ae. aegypti homogenate, making it a feasible, practical, and immediately adoptable protocol for use among vector control and other entities, particularly in the endemic areas of CHIKV, DENVs and ZIKV.

An overview of chikungunya virus molecular biology, epidemiology, pathogenesis, treatment and prevention strategies

The chikungunya virus (CHIKV) causes a devastating musculoskeletal inflammatory disease with symptoms of headache, rash, polyarthralgia, fever and myalgia. CHIKV has appeared intermittently around the world and in different ecological zones of Pakistan. Aedes mosquito species are the main vectors of CHIKV transmission and cause high disease rates in the urban transmission cycle. Even though the CHIKV is responsible for many cases of disease, no authorized antibodies or antiviral treatments are available, and prevention is the primary countermeasure. This review describes an update on CHIKV molecular biology, replication cycle, epidemiology, ecological factors, clinical manifestations and treatment and suggests a way forward to control and prevent this infection strategically in the future.

Re-Cellularised Kidney Scaffold for Chikungunya Virus Propagation: A Novel Approach

Background:

Re-emerging viral attacks are catastrophic for health and economy. It is crucial to grasp the viral life cycle, replication and mutation policies and attack strategies. It is also absolute to fathom the cost-efficient antiviral remedies earliest possible.

Methods:

We propose to use a lab-grown organ (re-cellularized scaffold of sheep kidney) for viral culture and understand its interaction with extra-cellular matrices of the host tissue.

Results:

Our findings showed that the chikungunya virus (CHIKV) could be better replicated in tissue-engineered bio models than cell culture. A decrease in ds-DNA levels emphasized that CHIKV propagates within the re-cellularized and cell culture models. There was an increase in the viral titres (pfu/ml) in re-cellularized scaffolds and control groups. The lipid peroxidation levels were increased as the infection was progressed in cell culture as well as re-cellularized and control groups. The onset and progress of the CHIKV attacks (cellular infection) lead to transmembrane domain fatty acid peroxidation and DNA breakdown, landing in cellular apoptosis. Simultaneously cell viability was inversely proportional to non-viability, and it decreased as the infection progressed in all infected groups. Histological findings and extracellular matrix evaluation showed the impairment in medullary, cortex regions due to propagation of CHIKV and plaques generations.

Conclusion:

This method will be a breakthrough for future virus culture, drug interaction and to study its effect on extracellular matrix alterations. This study will also allow us to investigate the correct role of any vaccine or antiviral drugs and their effects on re-engineered organ matrices before moving towards the animal models.

Graphical abstract

Molecular and biological characterization of an Asian-American isolate of Chikungunya virus

Chikungunya virus is an arthropod-transmitted virus that causes chikungunya fever, a disease characterized by severe muscle and joint pain. In 2013, the virus was introduced to the Americas and caused approximately 2.7 million cases of infection during the subsequent two years. The lack of knowledge regarding the biological behavior of the viral strains circulating during the outbreak motivated the characterization of an isolate from the Colombian outbreak, starting from analysis of the complete genome to the biological behavior in vitro. The full genome was retrieved using next-generation sequencing. The infective and replicative capacities were evaluated in HEK293T, Huh-7, and MRC-5 cell lines. The infection rates were determined by flow cytometry, and the cytopathic effect was assessed by a resazurin fluorescent metabolic assay. The viral yield was quantified using the virus plaque formation assay, while the viral proteins and genomic RNA kinetics were subsequently evaluated by western-blot and RT-qPCR. The COL7624 isolate clustered with other American and Caribbean sequences in the Asian American lineage. The T669A substitution in E2 protein distinguished it from other Colombian sequences reported in 2014. After 48 h post infection (hpi), the three cell lines analyzed reached infection percentages exceeding 65%, generating a high load of infectious viral progeny. The infection kinetics indicated that the replication peak of this CHIKV isolate is around 24 hpi, although gRNA is detectable in the culture supernatant from 4 hpi onwards. The infection caused the overexpression of interferon and pro-inflammatory cytokines, such as IL-1β, TNF-α, and IL-8. The COL7624 CHIKV isolate exhibited a high infective and replicative capacity as well as activation of cellular immune responses, similar to isolates belonging to the other genotypes.

Human Genetic Host Factors and Its Role in the Pathogenesis of Chikungunya Virus Infection

Chikungunya virus (CHIKV) is an alphavirus from the Togaviridae family that causes acute arthropathy in humans. It is an arthropod-borne virus transmitted initially by the Aedes (Ae) aegypti and after 2006's epidemic in La Reunion by Ae albopictus due to an adaptive mutation of alanine for valine in the position 226 of the E1 glycoprotein genome (A226V). The first isolated cases of CHIKV were reported in Tanzania, however since its arrival to the Western Hemisphere in 2013, the infection became a pandemic. After a mosquito bite from an infected viremic patient the virus replicates eliciting viremia, fever, rash, myalgia, arthralgia, and arthritis. After the acute phase, CHIKV infection can progress to a chronic stage where rheumatic symptoms can last for several months to years. Although there is a great number of studies on the pathogenesis of CHIKV infection not only in humans but also in animal models, there still gaps in the proper understanding of the disease. To this date, it is unknown why a percentage of patients do not develop clinical symptoms despite having been exposed to the virus and developing an adaptive immune response. Also, controversy stills exist on the pathogenesis of chronic joint symptoms. It is known that host immune response to an infectious disease is reflected on patient's symptoms. At the same time, it is now well-established that host genetic variation is an important component of the varied onset, severity, and outcome of infectious disease. It is essential to understand the interaction between the aetiological agent and the host to know the chronic sequelae of the disease. The present review summarizes the current findings on human host genetics and its relationship with immune response in CHIKV infection.

Was It Chikungunya? Laboratorial and Clinical Investigations of Cases Occurred during a Triple Arboviruses’ Outbreak in Rio de Janeiro, Brazil

The co-circulation of chikungunya virus (CHIKV), dengue virus (DENV) and Zika virus (ZIKV) in Rio de Janeiro (RJ), Brazil, caused a challenging triple epidemic, as they share similar clinical signs and symptoms and geographical distribution. Here, we aimed to investigate the clinical and laboratorial aspects of chikungunya suspected cases assisted in RJ during the 2018 outbreak, focusing on the differential diagnosis with dengue and zika. All suspected cases were submitted to molecular and/or serological differential diagnostic approaches to arboviruses. A total of 242 cases suspected of arbovirus infection were investigated and 73.6% (178/242) were molecular and/or serologically confirmed as chikungunya. In RT-qPCR confirmed cases, cycle threshold (Ct) values ranged from 15.46 to 35.13, with acute cases presenting lower values. Chikungunya cases were mainly in females (64%) and the most frequently affected age group was adults between 46 to 59 years old (27%). Polyarthralgia affected 89% of patients, especially in hands and feet. No dengue virus (DENV) and Zika virus (ZIKV) infections were confirmed by molecular diagnosis, but 9.5% (23/242) had serological evidence of DENV exposure by the detection of specific anti-DENV IgM or NS1, and 42.7% (76/178) of chikungunya positive cases also presented recent DENV exposure reflected by a positive anti-DENV IgM or NS1 result. A significantly higher frequency of arthritis (p = 0.023) and limb edema (p < 0.001) was found on patients with CHIKV monoinfection compared to dengue patients and patients exposed to both viruses. Lastly, phylogenetic analysis showed that the chikungunya cases were caused by the ECSA genotype. Despite the triple arboviruses’ epidemic in the state of RJ, most patients with fever and arthralgia investigated here were diagnosed as chikungunya cases, and the incidence of CHIKV/DENV co-detection was higher than that reported in other studies.