Ixchiq (VLA1553): The first FDA-approved vaccine to prevent disease caused by Chikungunya virus infection

Arboviruses: the hidden danger of the tropics

Arboviruses are viruses that are transmitted by arthropods such as mosquitoes, ticks, and flies, and most of them are RNA viruses. Vector-borne transmission occurs when an infected arthropod bites a vertebrate host, allowing the virus to enter the bloodstream and initiate infection. Arboviruses are known to cause significant morbidity and mortality in mammals, and at least a hundred of them have been identified as human pathogens. In this review, we provide an updated overview of four prominent arboviruses that are present in Southeast Asia (SEA): dengue virus (DENV), Japanese encephalitis virus (JEV), Zika virus (ZIKV), and chikungunya virus (CHIKV). The epidemiology and pathogenesis of these viruses and the currently used methods for diagnosis, prevention, and treatment of arbovirus infections are discussed in detail. Finally, we summarise the concerns and future considerations for combating these dangerous pathogens.

Cryo-EM reveals a double oligomeric ring scaffold of the CHIKV nsP3 peptide in complex with the NTF2L domain of host G3BP1

Chikungunya virus (CHIKV) poses a severe threat to global public health. The interaction between CHIKV nsP3 and host G3BP1 is critical for viral replication. However, the exact structural mechanism of the nsP3-G3BP1 interaction is scarce. Here, we report a cryo-electron microscopy structure of an octameric-heterotrimer formed by CHIKV nsP3 peptide (designated as CHIKV-43) in complex with the nuclear translocation factor 2-like (NTF2L) domain of G3BP1. The overall structure presents a double-layer ring scaffold. Two FGDF motifs and two alpha helices of CHIKV-43 are essential to bind NTF2L. Particularly, the secondary alpha helix plays key roles in forming the CHIKV-43-NTF2L high-order oligomer. We next analyzed the detailed interactions between CHIKV-43 and the NTF2L domain. The different binding patterns of NTF2L with its various partners were described as well. Subsequently, we demonstrated that the CHIKV-43 peptide is a crucial factor for nsP3 co-localization with G3BP1, reducing stress granule formation and interfering with interferon production. Overall, our findings present the structural and functional mechanisms on CHIKV nsP3 modulating host G3BP1 and provide a potential antiviral target based on the protein-protein interaction interface.

IMPORTANCE

Chikungunya virus (CHIKV) is an arbovirus responsible for causing fever, headache, and severe joint pain in humans, with widespread outbreaks affecting millions worldwide. The CHIKV nsP3 is a key protein that interacts with multiple host proteins. In this study, we present the cryo-electron microscopy structure of a high-order oligomer formed by the CHIKV nsP3 peptide and the nuclear translocation factor 2-like (NTF2L) domain of host protein G3BP1, revealing a completely novel interaction model. The detailed interactions within this oligomer were illustrated. We also analyzed the binding patterns of the NTF2L domain of G3BP1 with its various partners, providing essential insights for the development of peptide-mimetic inhibitors targeting nsP3 and/or G3BP1. Furthermore, our data indicate that the nsP3-G3BP1 interaction reduces stress granule formation and antagonizes interferon production. Overall, this study provides new knowledge on CHIKV biology and suggests a potential target for developing antiviral therapeutics.

Exploring the potential of direct-acting antivirals against Chikungunya virus through structure-based drug repositioning and molecular dynamic simulations

The Chikungunya virus (CHIKV) represents a significant global health threat, particularly in tropical regions, and no FDA-approved antiviral treatments are currently available. This study investigates the potential of Direct-Acting Antivirals (DAAs) and protease inhibitors (PIs) that have been developed for the hepatitis C virus (HCV) in treating CHIKV. We analyzed the binding of eight HCV DAAs to the nsP2 protease of CHIKV, which is essential for viral replication. Our findings suggest repurposing hepatitis C virus (HCV) antivirals, specifically Simeprevir (SIM) and voxilaprevir (VOX), could be effective against CHIKV. Through computational analyses, we observed their strong binding affinity to CHIKV's nsP2 protease, indicating the promising potential of repositioning these drugs for CHIKV treatment. To validate the results of our computational study, we evaluated the antiviral efficacy of SIM and VOX in vitro, both as monotherapies and in combination with ribavirin (RIBA). Our findings revealed that DAAs exert a multifaced effect by targeting different stages of the CHIKV life cycle. Furthermore, the synergistic effects suggest that combining SIM and VOX with RIBA may provide a more effective therapeutic strategy than using either drug alone. Further research is necessary to optimize treatment protocols and improve outcomes for patients affected by CHIKV.

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.

Novel peptide inhibitor for the Chikungunya virus nsP2 protease: Identification and characterization

Chikungunya virus (CHIKV) is an emerging pathogen affecting populations worldwide, with rapidly increasing infection rates. CHIKV, an arbovirus of the alphavirus genus, is predominantly found in tropical regions and transmitted by Aedes mosquitoes. Climate change has accelerated the global spread of these vectors, leading to outbreaks in non-tropical regions, including parts of Europe. The absence of antiviral therapies and the potential for co-infections with other viruses make CHIKV a significant public health concern. CHIKV replication relies on nsP2 cysteine protease activity to cleave its viral polyprotein into functional nonstructural and structural proteins. Targeting the nsP2 protease represents a promising strategy for antiviral therapy development. In this study, phage display was used to screen a library of peptides for potential binders of the target protease. Biophysical and biochemical analyses of the identified peptides assessed their inhibitory potential. Among the six identified peptides (named as P1-P6), four demonstrated inhibitory effects on the nsP2 protease (nsP2pro). Peptide P1 exhibited the strongest inhibitory effect, with a half-maximal inhibitory concentration (IC50) of 4.6 ± 1.9 µM, and a low cytotoxicity. The secondary structure analysis through CD spectroscopy and homology modelling revealed that P1 adopts an alpha-helical conformation. Finally, molecular dynamics simulations enabled us to investigate the dynamics of the nsP2pro active site and molecular docking was employed to predict the orthosteric binding mode of P1, providing insights into protein-peptide interaction. These findings underscore the potential of peptide P1 as a lead compound for further investigation in the context of CHIKV research.

Infectomics of Chikungunya Virus: Roles Played by Host Factors

Chikungunya virus (CHIKV), prevalent in tropical regions, is known for causing frequent outbreaks, particularly in Central Africa, South America, and Southeast Asia. It is an arbovirus transmitted by the Aedes (Ae.) aegypti and Ae. albopictus mosquitoes. Infections lead to severe joint and muscle pain, which can linger and significantly impair an individual's health, quality of life, and economic stability. Recent climatic changes and the globalization of travel have facilitated the worldwide spread of these mosquitoes. Currently, no U.S. Food and Drug Administration (FDA) approved drug is available for treating CHIKV infection. Recently, the FDA approved a live, attenuated vaccine called Ixchiq. However, this vaccine has been linked to side effects, leading the FDA to mandate additional post-marketing studies to assess the risk of severe adverse reactions similar to the virus. An emerging strategy in drug development focuses on targeting host factors that the virus exploits rather than the viral proteins themselves. This review explores the interactions between CHIKV and host factors that could be potential therapeutic targets. Despite progress in understanding the life cycle of CHIKV, the immune system's role in combating the virus still needs to be fully understood. Investigating treatments that enhance the host's immune response may offer new paths to combating CHIKV.

Neuropathogenesis of Old World Alphaviruses: Considerations for the Development of Medical Countermeasures

Chikungunya virus (CHIKV) and other alphaviruses that primarily induce arthritogenic disease in humans, known as "Old World" alphaviruses, present an emerging public health concern as geographic ranges of mosquito vectors expand due to climate change. While a vaccine against CHIKV has recently been approved by several countries in North America and Europe, access to effective preventative countermeasures against disease induced by Old World alphaviruses remains elusive for the most vulnerable populations. Furthermore, treatment options continue to be limited to supportive care. Atypical neurological disease manifestations caused by Old World alphaviruses, which make up as many as 25% of the cases in some CHIKV outbreaks, present special challenges when considering strategies for developing effective countermeasures. This review focuses on Old World alphaviruses, specifically CHIKV, Ross River virus, O'nyoug-nyoug virus, and Mayaro virus, concentrating on the atypical neurological disease manifestations they may cause. Our current understanding of Old World alphavirus neuropathogenesis, gained from human cases and preclinical animal models, is discussed, including viral and host factors' roles in disease development. The current state of alphavirus preventatives and treatments, both virus-targeting and host-directed therapies, is then summarized and discussed in the context of addressing neurological disease induced by Old World alphaviruses.

Phytochemical-based nanosystems: recent advances and emerging application in antiviral photodynamic therapy

Phytochemicals are typically natural bioactive compounds or metabolites produced by plants. Phytochemical-loaded nanocarrier systems, designed to overcome bioavailability limitations and enhance therapeutic effects, have garnered significant attention in recent years. The coronavirus disease 2019 (COVID-19) pandemic has intensified interest in the therapeutic application of phytochemicals to combat viral infections. This review explores nanoparticle-based treatment strategies incorporating phytochemicals for antiviral application, highlighting their demonstrated antiviral mechanisms. It specifically examines the antiviral activities of phytochemical-loaded nanosystems against (i) influenza virus (IAV), respiratory syncytial virus (RSV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); (ii) mosquito-borne viruses [dengue (DENV), Zika (ZIKV), and Chikungunya (CHIKV)]; and (iii) sexually transmitted/blood borne viruses [e.g. herpes simplex virus (HSV), human papillomavirus (HPV), and human immunodeficiency virus (HIV)]. Furthermore, this review highlights the emerging role of these nanosystems in photodynamic therapy (PDT)-mediated attenuation of viral proliferation, and offers a perspective on the future directions of research in this promising area of multimodal therapeutic approach.

Acute Clinical Features and Persistence of Joint Pain in Probable Cases of Chikungunya Fever in Eritrea

Background

Chikungunya fever is a mosquito-borne viral illness that has re-emerged as an important global concern. Persistent arthralgia following chikungunya fever is common and requires advanced pharmacological interventions as pain does not respond well to analgesics.

Objective

The study aimed to describe the acute clinical features of probable cases of chikungunya fever and risk factors associated with the persistence of joint pain.

Methods

A prospective, descriptive cohort study was conducted on probable cases of chikungunya fever from October 2018 to March 2019 in the Tesseney subzone of Eritrea.

Results

A total of 203 probable cases of chikungunya fever were enrolled, majority being males (68%) with a mean age of 39.2 years. The acute phase symptoms include the triad of polyarthralgia (97%), fever (96.1%), and skin rash (56.7%). Commonly affected joint sites were the wrist (59.4%) and interphalangeal joints of the hands (56.9%). Fever had a mean duration of 4.1 ± 3 days, while headache had a mean duration of 3.8 ± 3 days. Skin rash was maculopapular, which was pruritic in (85.2%) and the common involved sites were the hands (71%) and trunk (46.5%). Complete blood count during acute phase includes lymphocytosis (64.5%) and granulocytopenia (43.3%). Joint pain persisted at three months in 52.1% of cases and at six months in 21.7%. Age >41 (p = 0.001, OR: 1.588; 95% CI: 0.935-2.695) and having the O-type blood group (p = 0.033, OR: 0.704; 95% CI: 0.448-1.105) were found to be associated with the persistence of joint pain.

Conclusion

Our study indicates polyarthralgia, fever, and skin rash as a triad of symptoms during the acute phase. Persistent arthralgia was a frequent long-term complication of chikungunya fever in which increasing age was identified to be a significant risk factor.

Rising Incidence and Spatiotemporal Dynamics of Emerging and Reemerging Arboviruses in Brazil

BACKGROUND

Brazil has witnessed the co-circulation of dengue virus (DENV), Zika virus (ZIKV), and chikungunya virus (CHIKV), with outbreaks exacerbated by environmental factors, social determinants, and poor sanitation. The recent re-emergence of Oropouche virus (OROV) has added complexity to vector control strategies, emphasizing the need for integrated approaches to curb arboviruses spread. We aimed to analyze temporal trends and spatial distributions with national scope of these emerging arboviruses.

METHODS

An ecological study using data from the Brazilian Notifiable Diseases Information System the period from 2023 to 2024 was undertaken. Temporal trends were evaluated using Joinpoint regression, while spatial analysis was conducted using Moran's I, and local indicators of spatial association.

RESULTS

Dengue fever cases increased by 322%, while Oropouche fever (OF) increased by 300%. The states of Amazonas and Espírito Santo reported increases in OF cases. Moran's I test revealed spatial clustering of DENV and CHIKV. Two municipalities in the state of Mato Grosso do Sul showed cocirculation of DENV, CHIKV, and ZIKV.

CONCLUSIONS

This study identified a surge in arbovirus cases between 2023 and 2024, with peak incidences from January to March and October to December, linked to favorable climatic conditions. Clustering patterns and co-circulation of arboviruses highlight the need for tailored control and prevention strategies and targeted interventions to mitigate their impact.

Unraveling the Molecular Mechanisms of Mosquito Salivary Proteins: New Frontiers in Disease Transmission and Control

Mosquito-borne diseases are a group of illnesses caused by pathogens transmitted by mosquitoes, and they are globally prevalent, particularly in tropical and subtropical regions. Pathogen transmission occurs during mosquito blood feeding, a process in which mosquito saliva plays a crucial role. Mosquito saliva contains a variety of biologically active proteins that facilitate blood feeding by preventing blood clotting, promoting vasodilation, and modulating the host's immune and inflammatory responses. These effects create an environment conducive to pathogen invasion and dissemination. Specific mosquito salivary proteins (MSPs) can promote pathogen transmission through mechanisms that either regulate hosts' anti-infective immune responses or directly enhance pathogens' activity. Strategies targeting these MSPs have emerged as an innovative and promising approach for the control of mosquito-borne diseases. Meanwhile, the diversity of these proteins and their complex interactions with the host immune system necessitate further research to develop safer and more effective interventions. This review examines the functional diversity of MSPs and their roles in disease transmission, discusses the advantages and challenges of strategies targeting these proteins, and explores potential future directions for research in this area.

Withaferin A inhibits Chikungunya virus nsP2 protease and shows antiviral activity in the cell culture and mouse model of virus infection

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus causing fever, myalgia, and debilitating joint swelling and pain, which in many patients becomes chronic. The frequent epidemics of CHIKV across the world pose a significant public health burden necessitating the development of effective antiviral therapeutics. A cellular imaging-based high-content screening of natural compounds identified withaferin A (WFA), a steroidal lactone isolated from the plant Withania somnifera, as a potent antiviral against CHIKV. In the ERMS cells, WFA inhibited CHIKV replication early during the life cycle by binding the CHIKV non-structural protein nsP2 and inhibiting its protease activity. This inhibited the viral polyprotein processing and the minus-sense viral RNA synthesis. WFA mounted the nsP2 protease inhibitory activity through its oxidising property as the reducing agents N-acetylcysteine and Glutathione-monoethyl ester effectively reversed the WFA-mediated protease inhibition in vitro and abolished the WFA-mediated antiviral activity in cultured cells. WFA inhibited CHIKV replication in the C57BL/6 mouse model of chikungunya disease, resulting in significantly lower viremia. Importantly, CHIKV-infected mice showed significant joint swelling which was not seen in WFA-treated mice. These data demonstrate the potential of WFA as a novel CHIKV antiviral.

[Vaccinations for emerging and re-emerging viral diseases]

BACKGROUND

Emerging or re-emerging viral diseases have a pandemic potential and threaten global health. Vaccination is of crucial importance in the prevention of emerging and re-emerging viral diseases.

OBJECTIVE

Description of the current status of vaccine development against Filoviridae, highly pathogenic coronaviruses, smallpox viruses, influenza viruses and arboviruses.

MATERIAL AND METHODS

Focused literature search.

RESULTS

The World Health Organization (WHO) regularly publishes a list of infectious diseases that are expected to pose a major threat to humanity as they are could potentially trigger new pandemics; however, in addition to these human-to-human transmissible diseases, some arboviruses also have pandemic potential. In recent years numerous new vaccines, some of which are highly effective, have been licensed against new and re-emerging viral diseases and other promising vaccine candidates are currently in development.

CONCLUSION

There are still gaps in the development of vaccines in the area of Filoviridae and highly pathogenic coronaviruses. Vaccinations against smallpox viruses have been available for a long time. Developing influenza vaccines against novel strains in a timely manner is a challenge and universal influenza vaccines could be a possible solution. Modern vaccines are available against the arboviruses dengue and Chikungunya fever.

Host-Driven Ubiquitination Events in Vector-Transmitted RNA Virus Infections as Options for Broad-Spectrum Therapeutic Intervention Strategies

Many vector-borne viruses are re-emerging as public health threats, yet our understanding of the virus-host interactions critical for productive infection remains limited. The ubiquitination of proteins, including host- and pathogen-derived proteins is a highly prominent and consistent post-translational modification that regulates protein function through signaling and degradation. Viral proteins are documented to hijack the host ubiquitination machinery to modulate multiple host processes including antiviral defense mechanisms. The engagement of the host ubiquitination machinery in the post-translational modification of viral proteins to support aspects of the viral life cycle including assembly and egress is also well documented. Exploring the role ubiquitination plays in the life cycle of vector-transmitted viral pathogens will increase the knowledge base pertinent to the impact of host-enabled ubiquitination of viral and host proteins and the consequences on viral pathogenesis. In this review, we explore E3 ligase-regulated ubiquitination pathways functioning as proviral and viral restriction factors in the context of acutely infectious, vector-transmitted viral pathogens and the potential for therapeutically targeting them for countermeasures development.

From bench to clinic: the development of VLA1553/IXCHIQ, a live-attenuated chikungunya vaccine

BACKGROUND

Over the past 20 years, over 5 million cases of chikungunya, a mosquito-transmitted viral disease, have been reported in over 110 countries. Until recently, preventative strategies for chikungunya were largely ineffective, relying on vector control and individual avoidance of mosquito bites.

METHODS

This review outlines the preclinical and clinical efficacy and safety data that led to the approval of VLA1553 (IXCHIQ®), a live-attenuated vaccine against chikungunya disease. It also describes the innovative development pathway of VLA1553, based on an immunological surrogate of protection, and discusses ongoing and future post-licensure studies.

RESULTS

In mice and non-human primate models, VLA1553 elicited high titres of neutralizing antibodies, conferred protection against wild-type chikungunya virus challenge and raised no safety concerns. A Phase 1 clinical trial of VLA1553 demonstrated 100% seroconversion among 120 healthy participants, with sustained neutralizing antibody titres after 12 months. These results and determination of a surrogate marker of protection led to advancement of VLA1553 directly into Phase 3 clinical development, as agreed with the US Food and Drug Administration (FDA) and the European Medicines Agency. The pivotal Phase 3 trial met its primary immunogenicity endpoint, achieving seroprotective levels based on immuno-bridging in baseline seronegative participants 28 days post-vaccination. These findings enabled submission of a Biologics Licence Application to the FDA for accelerated approval of VLA1553 in the US for adults aged ≥18 years. Ongoing and planned studies will confirm the clinical efficacy/effectiveness and safety of VLA1553 in adults and younger individuals, and will generate data in chikungunya endemic countries that have the highest unmet need.

CONCLUSION

VLA1553 is the first vaccine approved for the prevention of chikungunya disease in adults, following accelerated development based on a serological surrogate marker of protection. VLA1553 adds to strategies to reduce the spread and burden of chikungunya in endemic populations and travellers.

Synthetic recovery of Yada Yada virus expands insect-specific alphavirus knowledge and facilitates production of chimeric viruses

Few insect-specific alphaviruses (ISA) have been discovered, with even fewer culturable to facilitate full characterisation. Here, we report the recovery of an infectious clone of Yada Yada virus (YYV)-a virus previously only detected by metagenomic sequencing of mosquito homogenates. Using the infectious clone, we confirmed the inability of YYV to replicate in vertebrate cells in vitro, with replication limited to only Aedes mosquito-derived cell lines. We further produced and characterised the first monoclonal antibodies (mAbs) to ISAs. Through successful replacement of the structural proteins of YYV with those of other ISAs, Eilat virus, Agua Salud (ASALV), Taï Forest (TALV) and Mwinilunga alphaviruses (MWAV), we established that a replication block for in vitro culture of TALV and MWAV in mosquito cells does not exist at virus entry. Unexpectedly, ASALV structural proteins were recognised by cross-reactive mAbs made to chikungunya (CHIKV) and Ross River viruses (RRV), suggesting a potential antigenic link between ASALV and pathogenic alphaviruses. The YYV genetic backbone was also investigated to generate chimeras displaying the structural proteins of various pathogenic vertebrate-infecting alphaviruses including CHIKV, RRV, Barmah Forest, Sindbis and Mayaro viruses. These chimeras retained the antigenic properties of the parental viruses and did not replicate in vertebrate cells, demonstrating the potential of the YYV platform for vaccine and diagnostic antigen production.

Immunogenicity Analysis of Chikungunya Virus DNA Vaccine Based on Mutated Putative N-Linked Glycosylation Sites of the Envelope Protein

Chikungunya fever is a mosquito-borne infectious disease caused by the chikungunya virus (CHIKV). Recently, CHIKV has spread rapidly worldwide, raising global concerns. However, there is only one approved vaccine is available to prevent CHIKV infection; therefore, different platform vaccines development is a public health priority. The CHIKV genome encodes four non-structural polyproteins (nsP1-4) and one structural polyprotein (capsid, envelope 3, envelope 2, 6 K, and envelope 1). Previous studies have shown that N-linked glycans in viral proteins play important roles in regulating immune responses. Accordingly, in this study, we designed four CHIKV DNA vaccine candidates with mutated N-glycosylation sites in the full-length E and E I/II proteins. Our results indicated that immunization of mice with the vaccine elevated the cytokines levels, including IFN-γ, associated with T cell immune response. Furthermore, the truncated E protein with a deleted E III domain (E I/II) exhibited better immunogenicity than the full-length E protein, and N-linked glycosylation of E I/II protein induced a higher cell-mediated immune response. Overall, our study demonstrates that N-linked glycosylation of the E I/II proteins of CHIKV significantly enhances cell-mediated immune responses, laying the foundation for the development of potential vaccination strategies against CHIKV.

Displaying alphavirus physicochemical consensus antigens on immunogenic liposomes enhances antibody elicitation in mice

Cobalt-porphyrin phospholipid displays recombinant protein antigens on liposome surfaces via antigen polyhistidine-tag (His-tag), and when combined with monophosphorylated lipid A and QS-21 yields the "CPQ" vaccine adjuvant system. In this proof of principle study, CPQ was used to generate vaccine prototypes that elicited antibodies for two different alphaviruses (AV). Mice were immunized with computationally designed, His-tagged, physicochemical property consensus (PCPcon) protein antigens representing the variable B-domain of the envelope protein 2 (E2) from the serotype specific Venezuelan Equine Encephalitis Virus (VEEVcon) or a broad-spectrum AV-antigen termed EVCcon. The CPQ adjuvant enhanced the antigenicity of both proteins without eliciting detectable anti-His-tag antibodies. Antibodies elicited from mice immunized with antigens admixed with CPQ showed orders-of-magnitude higher levels of antigen-specific IgG compared to alternative control adjuvants. The ELISA results correlated with antiviral activity against VEEV strain TC83 and more weakly to Chikungunya virus 118/25. Thus, display of E.coli-produced His-tagged E2 protein segments on the surface of immunogenic liposomes elicits high levels of antigen-specific and AV neutralizing antibodies in mice with vaccination, while facilitating vaccine preparation and providing dose-sparing potential.

Mayaro Virus: An Emerging Alphavirus in the Americas

Mayaro virus (MAYV) is an arbovirus first isolated in Trinidad and Tobago in 1954. MAYV is the causative agent of Mayaro fever, which is characterised by high fever, maculopapular rash, myalgia and arthralgia. The potential for chronic arthralgia is of particular clinical concern. Currently, MAYV outbreaks are restricted to South and Central America, with some cases reported in Africa as well as several imported cases in Europe. However, in recent years, MAYV has become a growing global concern due to its potential to emerge into urban transmission cycles. Challenges faced with diagnostics, as well as a lack of specific antivirals or licensed vaccines further exacerbate the potential global health threat posed by MAYV. In this review, we discuss this emerging arboviral threat with a particular focus on the current treatment and vaccine development efforts. Overall, MAYV remains a neglected arbovirus due to its limited area of transmission. However, with the potential of its urbanisation and expanding circulation, the threat MAYV poses to global health cannot be overlooked. Further research into the improvement of current diagnostics, as well as the development of efficacious antivirals and vaccines will be crucial to help prevent and manage potential MAYV outbreaks.

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.

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.