Effect of a Chikungunya Virus-Like Particle Vaccine on Safety and Tolerability Outcomes: A Randomized Clinical Trial

Vaccine value profile for Chikungunya

Chikungunya virus (CHIKV) a mosquito-borne alphavirus is the causative agent of Chikungunya (CHIK), a disease with low mortality but high acute and chronic morbidity resulting in a high overall burden of disease. After the acute disease phase, chronic disease including persistent arthralgia is very common, and can cause fatigue and pain that is severe enough to limit normal activities. On average, around 40% of people infected with CHIKV will develop chronic arthritis, which may last for months or years. Recommendations for protection from CHIKV focus on infection control through preventing mosquito proliferation. There is currently no licensed antiviral drug or vaccine against CHIKV. Therefore, one of the most important public health impacts of vaccination would be to decrease burden of disease and economic losses in areas impacted by the virus, and prevent or reduce chronic morbidity associated with CHIK. This benefit would particularly be seen in Low and Middle Income Countries (LMIC) and socio-economically deprived areas, as they are more likely to have more infections and more severe outcomes. This 'Vaccine Value Profile' (VVP) for CHIK is intended to provide a high-level, holistic assessment of the information and data that are currently available to inform the potential public health, economic and societal value of vaccines in the development pipeline and vaccine-like products.This VVP was developed by a working group of subject matter experts from academia, non-profit organizations, public private partnerships, and multi-lateral organizations. All contributors have extensive expertise on various elements of the CHIK VVP and collectively aimed to identify current research and knowledge gaps.The VVP was developed using only existing and publicly available information.

Chikungunya virus vaccine: a decade of progress solving epidemiological dilemma, emerging concepts, and immunological interventions

Chikungunya virus (CHIKV), a single-stranded RNA virus transmitted by Aedes mosquitoes, poses a significant global health threat, with severe complications observed in vulnerable populations. The only licensed vaccine, IXCHIQ, approved by the US FDA, is insufficient to address the growing disease burden, particularly in endemic regions lacking herd immunity. Monoclonal antibodies (mAbs), explicitly targeting structural proteins E1/E2, demonstrate promise in passive transfer studies, with mouse and human-derived mAbs showing protective efficacy. This article explores various vaccine candidates, including live attenuated, killed, nucleic acid-based (DNA/RNA), virus-like particle, chimeric, subunit, and adenovirus vectored vaccines. RNA vaccines have emerged as promising candidates due to their rapid response capabilities and enhanced safety profile. This review underscores the importance of the E1 and E2 proteins as immunogens, emphasizing their antigenic potential. Several vaccine candidates, such as CHIKV/IRES, measles vector (MV-CHIK), synthetic DNA-encoded antibodies, and mRNA-lipid nanoparticle vaccines, demonstrate encouraging preclinical and clinical results. In addition to identifying potential molecular targets for antiviral therapy, the study looks into the roles played by Toll-like receptors, RIG-I, and NOD-like receptors in the immune response to CHIKV. It also offers insights into novel tactics and promising vaccine candidates. This article discusses potential antiviral targets, the significance of E1 and E2 proteins, monoclonal antibodies, and RNA vaccines as prospective Chikungunya virus vaccine candidates.

Nanocarriers of antigen proteins for vaccine delivery

Nanoformulations in vaccinology provide antigen stability and enhanced immunogenicity, in addition to providing targeted delivery and controlled release. In the last years, much research has been focused on vaccine development using virus-like particles, liposomes, emulsions, polymeric, lipid, and inorganic nanoparticles. Importantly, nanoparticle interactions with innate and adaptive immune systems must be clearly understood to guide the rational development of nanovaccines. This review provides a recap and updates on different aspects advocating nanoparticles as promising antigen carriers and immune cell activators for vaccination. Moreover, it offers a discussion of how the physicochemical properties of nanoparticles are modified to target specific cells and improve vaccine efficacy.

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.

Generating prophylactic immunity against arboviruses in vertebrates and invertebrates

The World Health Organization recently declared a global initiative to control arboviral diseases. These are mainly caused by pathogenic flaviviruses (such as dengue, yellow fever and Zika viruses) and alphaviruses (such as chikungunya and Venezuelan equine encephalitis viruses). Vaccines represent key interventions for these viruses, with licensed human and/or veterinary vaccines being available for several members of both genera. However, a hurdle for the licensing of new vaccines is the epidemic nature of many arboviruses, which presents logistical challenges for phase III efficacy trials. Furthermore, our ability to predict or measure the post-vaccination immune responses that are sufficient for subclinical outcomes post-infection is limited. Given that arboviruses are also subject to control by the immune system of their insect vectors, several approaches are now emerging that aim to augment antiviral immunity in mosquitoes, including Wolbachia infection, transgenic mosquitoes, insect-specific viruses and paratransgenesis. In this Review, we discuss recent advances, current challenges and future prospects in exploiting both vertebrate and invertebrate immune systems for the control of flaviviral and alphaviral diseases.

Enhanced attenuation of chikungunya vaccines expressing antiviral cytokines

Alphaviruses are vector-borne, medically relevant, positive-stranded RNA viruses that cause disease in animals and humans worldwide. Of this group, chikungunya virus (CHIKV) is the most significant human pathogen, responsible for generating millions of infections leading to severe febrile illness and debilitating chronic joint pain. Currently, there are limited treatments to protect against alphavirus disease; thus, there is a tremendous need to generate safe and effective vaccines. Live-attenuated vaccines (LAVs) are cost-effective and potent immunization strategies capable of generating long-term protection in a single dose. However, LAVs often produce systemic viral replication, which can lead to unwanted post-vaccination side effects and pose a risk of reversion to a pathogenic phenotype and transmission to mosquitoes. Here, we utilized a chimeric infectious clone of CHIKV engineered with the domain C of the E2 gene of Semliki Forest virus (SFV) to express IFNγ and IL-21-two potent antiviral and immunomodulatory cytokines-in order to improve the LAV's attenuation while maintaining immunogenicity. The IFNγ- and IL-21-expressing vaccine candidates were stable during passage and significantly attenuated post-vaccination, as mice experienced reduced footpad swelling with minimal systemic replication and dissemination capacity compared to the parental vaccine. Additionally, these candidates provided complete protection to mice challenged with WT CHIKV. Our dual attenuation strategy represents an innovative way to generate safe and effective alphavirus vaccines that could be applied to other viruses.

Immunogenicity, safety and duration of protection afforded by chikungunya virus vaccines undergoing human clinical trials

Background. Chikungunya virus (CHIKV) causes chikungunya fever and has been responsible for major global epidemics of arthritic disease over the past two decades. Multiple CHIKV vaccine candidates are currently undergoing or have undergone human clinical trials, with one vaccine candidate receiving FDA approval. This scoping review was performed to evaluate the 'efficacy', 'safety' and 'duration of protection' provided by CHIKV vaccine candidates in human clinical trials.Methods. This scoping literature review addresses studies involving CHIKV vaccine clinical trials using available literature on the PubMed, Medline Embase, Cochrane Library and Clinicaltrial.gov databases published up to 25 August 2023. Covidence software was used to structure information and review the studies included in this article.Results. A total of 1138 studies were screened and, after removal of duplicate studies, 12 relevant studies were thoroughly reviewed to gather information. This review summarizs that all seven CHIKV vaccine candidates achieved over 90 % seroprotection against CHIKV after one or two doses. All vaccines were able to provide neutralizing antibody protection for at least 28 days.Conclusions. A variety of vaccine technologies have been used to develop CHIKV vaccine candidates. With one vaccine candidate having recently received FDA approval, it is likely that further CHIKV vaccines will be available commercially in the near future.

Production, purification and immunogenicity of Gag virus-like particles carrying SARS-CoV-2 components

The virus-like particle (VLP) platform is a robust inducer of humoral and cellular immune responses; hence, it has been used in vaccine development for several infectious diseases. In the current work, VLPs carrying SARS-CoV-2 Spike (S) protein (Wuhan strain) with an HIV-1 Gag core were produced using suspension HEK 293SF-3F6 cells by transient transfection. The Gag was fused with green fluorescent protein (GFP) for rapid quantification of the VLPs. Five different versions of Gag-Spike VLPs (Gag-S-VLPs) consisting of Gag-S alone or combined with other SARS-CoV-2 components, namely Gag-S-Nucleocapsid (N), Gag-S-Matrix (M), Gag-S-Envelope (E), Gag-S-MEN, along with Gag alone were produced and processed by clarification, nuclease treatment, concentration by tangential flow filtration (TFF) and diafiltration. A pilot mouse study was performed to evaluate the immunogenicity of the Gag-S-VLPs through the measurement of the humoral and/or cellular responses against all the mentioned SARS-CoV-2 components. Antibody response to Spike was observed in all variants. The highest number of Spike-specific IFN-γ + T cells was detected with Gag-S-VLPs. No induction of antigen-specific cellular responses to M, N or E proteins were detected with any of the Gag-S, M, E/or N VLPs tested. Therefore, the Gag-S-VLP, by reason of consistently eliciting strong antigen-specific cellular and antibody responses, was selected for further evaluation. The purification process was improved by replacing the conventional centrifugation by serial microfiltration in the clarification step, followed by Spike-affinity chromatography to get concentrated VLPs with higher purity. Three different doses of Gag-S-VLP in conjunction with two adjuvants (Quil-A or AddaVax) were used to assess the dose-dependent antigen-specific cellular and antibody responses in mice. The Gag-S-VLP adjuvanted with Quil-A resulted in a stronger Spike-specific cellular response compared to that adjuvanted with AddaVax. A strong spike neutralisation activity was observed for all doses, independent of the adjuvant combination.

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.

Viral protein-based nanoparticles (part 2): Pharmaceutical applications

Viral protein nanoparticles (ViP NPs) such as virus-like particles and virosomes are structures halfway between viruses and synthetic nanoparticles. The biological nature of ViP NPs endows them with the biocompatibility, biodegradability, and functional properties that many synthetic nanoparticles lack. At the same time, the absence of a viral genome avoids the safety concerns of viruses. Such characteristics of ViP NPs offer a myriad of opportunities for theirapplication at several points across disease development: from prophylaxis to diagnosis and treatment. ViP NPs present remarkable immunostimulant properties, and thus the vaccination field has benefited the most from these platforms capable of overcoming the limitations of both traditional and subunit vaccines. This was reflected in the marketing authorization of several VLP- and virosome-based vaccines. Besides, ViP NPs inherit the ability of viruses to deliver their cargo to target cells. Because of that, ViP NPs are promising candidates as vectors for drug and gene delivery, and for diagnostic applications. In this review, we analyze the pharmaceutical applications of ViP NPs, describing the products that are commercially available or under clinical evaluation, but also the advances that scientists are making toward the implementation of ViP NPs in other areas of major pharmaceutical interest.

Equine Polyclonal Antibodies Prevent Acute Chikungunya Virus Infection in Mice

Chikungunya virus (CHIKV) is a mosquito-transmitted pathogen that causes chikungunya disease (CHIK); the disease is characterized by fever, muscle ache, rash, and arthralgia. This arthralgia can be debilitating and long-lasting, seriously impacting quality of life for years. Currently, there is no specific therapy available for CHIKV infection. We have developed a despeciated equine polyclonal antibody (CHIKV-EIG) treatment against CHIKV and evaluated its protective efficacy in mouse models of CHIKV infection. In immunocompromised (IFNAR^-/-) mice infected with CHIKV, daily treatment for five consecutive days with CHIKV-EIG administered at 100 mg/kg starting on the day of infection prevented mortality, reduced viremia, and improved clinical condition as measured by body weight loss. These beneficial effects were seen even when treatment was delayed to 1 day after infection. In immunocompetent mice, CHIKV-EIG treatment reduced virus induced arthritis (including footpad swelling), arthralgia-associated cytokines, viremia, and tissue virus loads in a dose-dependent fashion. Collectively, these results suggest that CHIKV-EIG is effective at preventing CHIK and could be a viable candidate for further development as a treatment for human disease.

A molecular understanding of alphavirus entry and antibody protection

Alphaviruses are arthropod-transmitted RNA viruses that cause epidemics of human infection and disease on a global scale. These viruses are classified as either arthritogenic or encephalitic based on their genetic relatedness and the clinical syndromes they cause. Although there are currently no approved therapeutics or vaccines against alphaviruses, passive transfer of monoclonal antibodies confers protection in animal models. This Review highlights recent advances in our understanding of the host factors required for alphavirus entry, the mechanisms of action by which protective antibodies inhibit different steps in the alphavirus infection cycle and candidate alphavirus vaccines currently under clinical evaluation that focus on humoral immunity. A comprehensive understanding of alphavirus entry and antibody-mediated protection may inform the development of new classes of countermeasures for these emerging viruses.

A phase 1, randomized, placebo-controlled, dose-ranging study to evaluate the safety and immunogenicity of an mRNA-based chikungunya virus vaccine in healthy adults

BACKGROUND

Chikungunya, a mosquito-borne viral disease caused by the chikungunya virus (CHIKV), causes a significant global health burden, and there is currently no approved vaccine to prevent chikungunya disease. In this study, the safety and immunogenicity of a CHIKV mRNA vaccine candidate (mRNA-1388) were evaluated in healthy participants in a CHIKV-nonendemic region.

METHODS

This phase 1, first-in-human, randomized, placebo-controlled, dose-ranging study enrolled healthy adults (ages 18-49 years) between July 2017 and March 2019 in the United States. Participants were randomly assigned (3:1) to receive 2 intramuscular injections 28 days apart with mRNA-1388 in 3 dose-level groups (25 μg, 50 μg, and 100 μg) or placebo and were followed for up to 1 year. Safety (unsolicited adverse events [AEs]), tolerability (local and systemic reactogenicity; solicited AEs), and immunogenicity (geometric mean titers [GMTs] of CHIKV neutralizing and binding antibodies) of mRNA-1388 versus placebo were evaluated.

RESULTS

Sixty participants were randomized and received ≥ 1 vaccination; 54 (90 %) completed the study. mRNA-1388 demonstrated favorable safety and reactogenicity profiles at all dose levels. Immunization with mRNA-1388 induced substantial and persistent humoral responses. Dose-dependent increases in neutralizing antibody titers were observed; GMTs (95 % confidence intervals [CIs]) at 28 days after dose 2 were 6.2 (5.1-7.6) for mRNA-1388 25 μg, 53.8 (26.8-108.1) for mRNA-1388 50 μg, 92.8 (43.6-197.6) for mRNA-1388 100 μg, and 5.0 (not estimable) for placebo. Persistent humoral responses were observed up to 1 year after vaccination and remained higher than placebo in the 2 higher mRNA-1388 dose groups. The development of CHIKV-binding antibodies followed a similar trend as that observed with neutralizing antibodies.

CONCLUSIONS

mRNA-1388, the first mRNA vaccine against CHIKV, was well tolerated and elicited substantial and long-lasting neutralizing antibody responses in healthy adult participants in a nonendemic region.

CLINICALTRIALS

gov: NCT03325075.

A chikungunya virus-like particle vaccine induces broadly neutralizing and protective antibodies against alphaviruses in humans

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that causes epidemics of acute and chronic musculoskeletal disease. Here, we analyzed the human B cell response to a CHIKV-like particle-adjuvanted vaccine (PXVX0317) from samples obtained from a phase 2 clinical trial in humans (NCT03483961). Immunization with PXVX0317 induced high levels of neutralizing antibody in serum against CHIKV and circulating antigen-specific B cells up to 6 months after immunization. Monoclonal antibodies (mAbs) generated from peripheral blood B cells of three PXVX0317-vaccinated individuals on day 57 after immunization potently neutralized CHIKV infection, and a subset of these inhibited multiple related arthritogenic alphaviruses. Epitope mapping and cryo-electron microscopy defined two broadly neutralizing mAbs that uniquely bind to the apex of the B domain of the E2 glycoprotein. These results demonstrate the inhibitory breadth and activity of the human B cell response induced by the PXVX0317 vaccine against CHIKV and potentially other related alphaviruses.

Comparative Efficacy of Mayaro Virus-Like Particle Vaccines Produced in Insect or Mammalian Cells

Mayaro virus (MAYV) is a mosquito-transmitted alphavirus that causes often debilitating rheumatic disease in tropical Central and South America. There are currently no licensed vaccines or antiviral drugs available for MAYV disease. Here, we generated Mayaro virus-like particles (VLPs) using the scalable baculovirus-insect cell expression system. High-level secretion of MAYV VLPs in the culture fluid of Sf9 insect cells was achieved, and particles with a diameter of 64 to 70 nm were obtained after purification. We characterize a C57BL/6J adult wild-type mouse model of MAYV infection and disease and used this model to compare the immunogenicity of VLPs from insect cells with that of VLPs produced in mammalian cells. Mice received two intramuscular immunizations with 1 μg of nonadjuvanted MAYV VLPs. Potent neutralizing antibody responses were generated against the vaccine strain, BeH407, with comparable activity seen against a contemporary 2018 isolate from Brazil (BR-18), whereas neutralizing activity against chikungunya virus was marginal. Sequencing of BR-18 illustrated that this virus segregates with genotype D isolates, whereas MAYV BeH407 belongs to genotype L. The mammalian cell-derived VLPs induced higher mean neutralizing antibody titers than those produced in insect cells. Both VLP vaccines completely protected adult wild-type mice against viremia, myositis, tendonitis, and joint inflammation after MAYV challenge. IMPORTANCE Mayaro virus (MAYV) is associated with acute rheumatic disease that can be debilitating and can evolve into months of chronic arthralgia. MAYV is believed to have the potential to emerge as a tropical public health threat, especially if it develops the ability to be efficiently transmitted by urban mosquito vectors, such as Aedes aegypti and/or Aedes albopictus. Here, we describe a scalable virus-like particle vaccine against MAYV that induced neutralizing antibodies against a historical and a contemporary isolate of MAYV and protected mice against infection and disease, providing a potential new intervention for MAYV epidemic preparedness.

Nanovaccines to combat virus-related diseases

The invention and application of vaccines have made tremendous contributions to fight against pandemics for human beings. However, current vaccines still have shortcomings such as insufficient cellular immunity, the lack of cross-protection, and the risk of antibody-dependent enhancement (ADE). Thus, the prevention and control of pandemic viruses including Ebola Virus, human immunodeficiency virus (HIV), Influenza A viruses, Zika, and current SARS-CoV-2 are still extremely challenging. Nanoparticles with unique physical, chemical, and biological properties, hold promising potentials for the development of ideal vaccines against these viral infections. Moreover, the approval of the first nanoparticle-based mRNA vaccine BNT162b has established historic milestones that greatly inspired the clinical translation of nanovaccines. Given the safety and extensive application of subunit vaccines, and the rapid rise of mRNA vaccines, this review mainly focuses on these two vaccine strategies and provides an overview of the nanoparticle-based vaccine delivery platforms to tackle the current and next global health challenges. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Chikungunya Virus: Priority Pathogen or Passing Trend?

Chikungunya virus (CHIKV) is considered a priority pathogen and a major threat to global health. While CHIKV infections may be asymptomatic, symptomatic patients can develop chikungunya fever (CHIKF) characterized by severe arthralgia which often transitions into incapacitating arthritis that could last for years and lead to significant loss in health-related quality of life. Yet, Chikungunya fever (CHIKF) remains a neglected tropical disease due to its complex epidemiology and the misrepresentation of its incidence and disease burden worldwide. Transmitted to humans by infected Aedes mosquitoes, CHIKV has dramatically expanded its geographic distribution to over 100 countries, causing large-scale outbreaks around the world and putting more than half of the population of the world at risk of infection. More than 50 years have passed since the first CHIKV vaccine was reported to be in development. Despite this, there is no licensed vaccine or antiviral treatments against CHIKV to date. In this review, we highlight the clinical relevance of developing chikungunya vaccines by discussing the poor understanding of long-term disease burden in CHIKV endemic countries, the complexity of CHIKV epidemiological surveillance, and emphasising the impact of the global emergence of CHIKV infections. Additionally, our review focuses on the recent progress of chikungunya vaccines in development, providing insight into the most advanced vaccine candidates in the pipeline and the potential implications of their roll-out.

An overview on the treatments and prevention against COVID-19

BACKGROUND

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to plague the world. While COVID-19 is asymptomatic in most individuals, it can cause symptoms like pneumonia, ARDS (acute respiratory distress syndrome), and death in others. Although humans are currently being vaccinated with several COVID-19 candidate vaccines in many countries, however, the world still is relying on hygiene measures, social distancing, and approved drugs.

RESULT

There are many potential therapeutic agents to pharmacologically fight COVID-19: antiviral molecules, recombinant soluble angiotensin-converting enzyme 2 (ACE2), monoclonal antibodies, vaccines, corticosteroids, interferon therapies, and herbal agents. By an understanding of the SARS-CoV-2 structure and its infection mechanisms, several vaccine candidates are under development and some are currently in various phases of clinical trials.

CONCLUSION

This review describes potential therapeutic agents, including antiviral agents, biologic agents, anti-inflammatory agents, and herbal agents in the treatment of COVID-19 patients. In addition to reviewing the vaccine candidates that entered phases 4, 3, and 2/3 clinical trials, this review also discusses the various platforms that are used to develop the vaccine COVID-19.

Virus-like Particles as Antiviral Vaccine: Mechanism, Design, and Application

Virus-like particles (VLPs) are viral structural protein that are noninfectious as they do not contain viral genetic materials. They are safe and effective immune stimulators and play important roles in vaccine development because of their intrinsic immunogenicity to induce cellular and humoral immune responses. In the design of antiviral vaccine, VLPs based vaccines are appealing multifunctional candidates with the advantages such as self-assembling nanoscaled structures, repetitive surface epitopes, ease of genetic and chemical modifications, versatility as antigen presenting platforms, intrinsic immunogenicity, higher safety profile in comparison with live-attenuated vaccines and inactivated vaccines. In this review, we discuss the mechanism of VLPs vaccine inducing cellular and humoral immune responses. We outline the impact of size, shape, surface charge, antigen presentation, genetic and chemical modification, and expression systems when constructing effective VLPs based vaccines. Recent applications of antiviral VLPs vaccines and their clinical trials are summarized.

Understanding the Biology and Immune Pathogenesis of Chikungunya Virus Infection for Diagnostic and Vaccine Development

Chikungunya virus, the causative agent of chikungunya fever, is generally characterized by the sudden onset of symptoms, including fever, rash, myalgia, and headache. In some patients, acute chikungunya virus infection progresses to severe and chronic arthralgia that persists for years. Chikungunya infection is more commonly identified in tropical and subtropical regions. However, recent expansions and epidemics in the temperate regions have raised concerns about the future public health impact of chikungunya diseases. Several underlying factors have likely contributed to the recent re-emergence of chikungunya infection, including urbanization, human travel, viral adaptation to mosquito vectors, lack of effective control measures, and the spread of mosquito vectors to new regions. However, the true burden of chikungunya disease is most likely to be underestimated, particularly in developing countries, due to the lack of standard diagnostic assays and clinical manifestations overlapping with those of other endemic viral infections in the regions. Additionally, there have been no chikungunya vaccines available to prevent the infection. Thus, it is important to update our understanding of the immunopathogenesis of chikungunya infection, its clinical manifestations, the diagnosis, and the development of chikungunya vaccines.

Chikungunya patient transcriptional signatures faithfully recapitulated in a C57BL/6J mouse model

Introduction

An adult wild-type C57BL/6J mouse model of chikungunya virus (CHIKV) infection and disease has been extensively used to study the alphaviral arthritic immunopathology and to evaluate new interventions. How well mouse models recapitulate the gene expression profiles seen in humans remains controversial.

Methods

Herein we perform a comparative transcriptomics analysis using RNA-Seq datasets from the C57BL/6J CHIKV mouse model with datasets obtained from adults and children acutely infected with CHIKV.

Results

Despite sampling quite different tissues, peripheral blood from humans and feet from mice, gene expression profiles were quite similar, with an overlap of up to ≈50% for up-regulated single copy orthologue differentially expressed genes. Furthermore, high levels of significant concordance between mouse and human were seen for immune pathways and signatures, which were dominated by interferons, T cells and monocyte/macrophages. Importantly, predicted responses to a series of anti-inflammatory drug and biologic treatments also showed cogent similarities between species.

Discussion

Comparative transcriptomics and subsequent pathway analysis provides a detailed picture of how a given model recapitulates human gene expression. Using this method, we show that the C57BL/6J CHIKV mouse model provides a reliable and representative system in which to study CHIKV immunopathology and evaluate new treatments.

Vaccine development for zoonotic viral diseases caused by positive‑sense single‑stranded RNA viruses belonging to the Coronaviridae and Togaviridae families (Review)

Outbreaks of zoonotic viral diseases pose a severe threat to public health and economies worldwide, with this currently being more prominent than it previously was human history. These emergency zoonotic diseases that originated and transmitted from vertebrates to humans have been estimated to account for approximately one billion cases of illness and have caused millions of deaths worldwide annually. The recent emergence of severe acute respiratory syndrome coronavirus-2 (coronavirus disease 2019) is an excellent example of the unpredictable public health threat causing a pandemic. The present review summarizes the literature data regarding the main vaccine developments in human clinical phase I, II and III trials against the zoonotic positive-sense single-stranded RNA viruses belonging to the Coronavirus and Alphavirus genera, including severe acute respiratory syndrome, Middle east respiratory syndrome, Venezuelan equine encephalitis virus, Semliki Forest virus, Ross River virus, Chikungunya virus and O'nyong-nyong virus. That there are neither vaccines nor effective antiviral drugs available against most of these viruses is undeniable. Therefore, new explosive outbreaks of these zoonotic viruses may surely be expected. The present comprehensive review provides an update on the status of vaccine development in different clinical trials against these viruses, as well as an overview of the present results of these trials.

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.

Safety and immunogenicity of PXVX0317, an aluminium hydroxide-adjuvanted chikungunya virus-like particle vaccine: a randomised, double-blind, parallel-group, phase 2 trial

BACKGROUND

Chikungunya virus (CHIKV) disease is an ongoing public health threat. We aimed to evaluate the safety and immunogenicity of PXVX0317, an aluminium hydroxide-adjuvanted formulation of a CHIKV virus-like particle (VLP) vaccine.

METHODS

This randomised, double-blind, parallel-group, phase 2 trial was conducted at three clinical trial centres in the USA. Eligible participants were healthy CHIKV-naïve adults aged 18-45 years. Participants were stratified by site and randomly assigned (1:1:1:1:1:1:1:1) to one of the eight vaccination groups using a block size of 16. Group 1 received two doses of unadjuvanted PXVX0317 28 days apart (2 × 20 μg; standard); all other groups received adjuvanted PXVX0317: groups 2-4 received two doses 28 days apart (2 × 6 μg [group 2], 2 × 10 μg [group 3], or 2 × 20 μg [group 4]; standard); group 4 also received a booster dose 18 months after the first active injection (40 μg; standard plus booster); groups 5-7 received two doses 14 days apart (2 × 6 μg [group 5], 2 × 10 μg [group 6], or 2 × 20 μg [group 7]; accelerated); and group 8 received one dose (1 × 40 μg; single). The primary endpoint was the geometric mean titre of anti-CHIKV neutralising antibody on day 57 (28 days after the last vaccination), assessed in the immunogenicity-evaluable population. Additionally, we assessed safety. This trial is registered at ClinicalTrials.gov, NCT03483961.

FINDINGS

This trial was conducted from April 18, 2018, to Sept 21, 2020; 468 participants were assessed for eligibility. Of these, 415 participants were randomly assigned to eight groups (n=53 in groups 1, 5, and 6; n=52 in groups 2 and 8; n=51 in groups 3 and 7; and n=50 in group 4) and 373 were evaluable for immunogenicity. On day 57, serum neutralising antibody geometric mean titres were 2057·0 (95% CI 1584·8-2670·0) in group 1, 1116·2 (852·5-1461·4; p=0·0015 vs group 1 used as a reference) in group 2, 1465·3 (1119·1-1918·4; p=0·076) in group 3, 2023·8 (1550·5-2641·7; p=0·93) in group 4, 920·1 (710·9-1190·9; p<0·0001) in group 5, 1206·9 (932·4-1562·2; p=0·0045) in group 6, 1562·8 (1204·1-2028·3; p=0·14) in group 7, and 1712·5 (1330·0-2205·0; p=0·32) in group 8. In group 4, a booster dose increased serum neutralising antibody geometric mean titres from 215·7 (95% CI 160·9-289·1) on day 547 to 10 941·1 (7378·0-16 225·1) on day 575. Durability of the immune response (evaluated in groups 1, 4, and 8) was shown up to 2 years. The most common solicited adverse event was pain at the injection site, reported in 12 (23%) of 53 participants who received the unadjuvanted vaccine (group 1) and 111 (31%) of 356 who received the adjuvanted vaccine. No vaccine-related serious adverse events were reported.

INTERPRETATION

PXVX0317 was well tolerated and induced a robust and durable serum neutralising antibody immune response against CHIKV up to 2 years. A single 40 μg injection of adjuvanted PXVX0317 is being further investigated in phase 3 clinical trials (NCT05072080 and NCT05349617).

FUNDING

Emergent BioSolutions.

Vaccines against Emerging and Neglected Infectious Diseases: An Overview

Neglected Tropical Diseases (NTDs) are a group of diseases that are highly prevalent in tropical and subtropical regions, and closely associated with poverty and marginalized populations. Infectious diseases affect over 1.6 billion people annually, and vaccines are the best prophylactic tool against them. Along with NTDs, emerging and reemerging infectious diseases also threaten global public health, as they can unpredictably result in pandemics. The recent advances in vaccinology allowed the development and licensing of new vaccine platforms that can target and prevent these diseases. In this work, we discuss the advances in vaccinology and some of the difficulties found in the vaccine development pipeline for selected NTDs and emerging and reemerging infectious diseases, including HIV, Dengue, Ebola, Chagas disease, malaria, leishmaniasis, zika, and chikungunya.

Safety and immunogenicity of a trivalent virus-like particle vaccine against western, eastern, and Venezuelan equine encephalitis viruses: a phase 1, open-label, dose-escalation, randomised clinical trial

BACKGROUND

Western (WEEV), eastern (EEEV), and Venezuelan (VEEV) equine encephalitis viruses are mosquito-borne pathogens classified as potential biological warfare agents for which there are currently no approved human vaccines or therapies. We aimed to evaluate the safety, tolerability, and immunogenicity of an investigational trivalent virus-like particle (VLP) vaccine, western, eastern, and Venezuelan equine encephalitis (WEVEE) VLP, composed of WEEV, EEEV, and VEEV VLPs.

METHODS

The WEVEE VLP vaccine was evaluated in a phase 1, randomised, open-label, dose-escalation trial at the Hope Clinic of the Emory Vaccine Center at Emory University, Atlanta, GA, USA. Eligible participants were healthy adults aged 18-50 years with no previous vaccination history with an investigational alphavirus vaccine. Participants were assigned to a dose group of 6 μg, 30 μg, or 60 μg vaccine product and were randomly assigned (1:1) to receive the WEVEE VLP vaccine with or without aluminium hydroxide suspension (alum) adjuvant by intramuscular injection at study day 0 and at week 8. The primary outcomes were the safety and tolerability of the vaccine (assessed in all participants who received at least one administration of study product) and the secondary outcome was immune response measured as neutralising titres by plaque reduction neutralisation test (PRNT) 4 weeks after the second vaccination. This trial is registered at ClinicalTrials.gov, NCT03879603.

FINDINGS

Between April 2, 2019, and June 13, 2019, 30 trial participants were enrolled (mean age 32 years, range 21-48; 16 [53%] female participants and 14 [47%] male participants). Six groups of five participants each received 6 μg, 30 μg, or 60 μg vaccine doses with or without adjuvant, and all 30 participants completed study follow-up. Vaccinations were safe and well tolerated. The most frequently reported symptoms were mild injection-site pain and tenderness (22 [73%] of 30) and malaise (15 [50%] of 30). Dose-dependent differences in the frequency of pain and tenderness were found between the 6 μg, 30 μg, and 60 μg groups (p=0·0217). No significant differences were observed between dosing groups for any other reactogenicity symptom. Two adverse events (mild elevated blood pressure and moderate asymptomatic neutropenia) were assessed as possibly related to the study product in one trial participant (60 μg dose with alum); both resolved without clinical sequelae. 4 weeks after second vaccine administration, neutralising antibodies were induced in all study groups with the highest response seen against all three vaccine antigens in the 30 μg plus alum group (PRNT₈₀ geometric mean titre for EEEV 60·8, 95% CI 29·9-124·0; for VEEV 111·5, 49·8-249·8; and for WEEV 187·9, 90·0-392·2). Finally, 4 weeks after second vaccine administration, for all doses, the majority of trial participants developed an immune response to all three vaccine components (24 [83%] of 29 for EEEV; 26 [90%] of 29 for VEEV; 27 [93%] of 29 for WEEV; and 22 [76%] of 29 for EEEV, VEEV, and WEEV combined).

INTERPRETATION

The favourable safety profile and neutralising antibody responses, along with pressing public health need, support further evaluation of the WEVEE VLP vaccine in advanced-phase clinical trials.

FUNDING

The Vaccine Research Center of the National Institute of Allergy and Infectious Diseases, National Institutes of Health funded the clinical trial. The US Department of Defense contributed funding for manufacturing of the study product.

Advances in Infectious Disease Vaccine Adjuvants

Vaccines are one of the most significant medical interventions in the fight against infectious diseases. Since their discovery by Edward Jenner in 1796, vaccines have reduced the worldwide transmission to eradication levels of infectious diseases, including smallpox, diphtheria, hepatitis, malaria, and influenza. However, the complexity of developing safe and effective vaccines remains a barrier for combating many more infectious diseases. Immune stimulants (or adjuvants) are an indispensable factor in vaccine development, especially for inactivated and subunit-based vaccines due to their decreased immunogenicity compared to whole pathogen vaccines. Adjuvants are widely diverse in structure; however, their overall function in vaccine constructs is the same: to enhance and/or prolong an immunological response. The potential for adverse effects as a result of adjuvant use, though, must be acknowledged and carefully managed. Understanding the specific mechanisms of adjuvant efficacy and safety is a key prerequisite for adjuvant use in vaccination. Therefore, rigorous pre-clinical and clinical research into adjuvant development is essential. Overall, the incorporation of adjuvants allows for greater opportunities in advancing vaccine development and the importance of immune stimulants drives the emergence of novel and more effective adjuvants. This article highlights recent advances in vaccine adjuvant development and provides detailed data from pre-clinical and clinical studies specific to infectious diseases. Future perspectives into vaccine adjuvant development are also highlighted.

Development of a next-generation chikungunya virus vaccine based on the HydroVax platform

Chikungunya virus (CHIKV) is an emerging/re-emerging mosquito-borne pathogen responsible for explosive epidemics of febrile illness characterized by debilitating polyarthralgia and the risk of lethal infection among the most severe cases. Despite the public health risk posed by CHIKV, no vaccine is currently available. Using a site-directed hydrogen peroxide-based inactivation approach, we developed a new CHIKV vaccine, HydroVax-CHIKV. This vaccine technology was compared to other common virus inactivation approaches including β-propiolactone (BPL), formaldehyde, heat, and ultraviolet (UV) irradiation. Heat, UV, and BPL were efficient at inactivating CHIKV-181/25 but caused substantial damage to neutralizing epitopes and failed to induce high-titer neutralizing antibodies in vaccinated mice. HydroVax-CHIKV and formaldehyde-inactivated CHIKV retained intact neutralizing epitopes similar to live virus controls but the HydroVax-CHIKV approach demonstrated a more rapid rate of virus inactivation. HydroVax-CHIKV vaccination induced high neutralizing responses to homologous and heterologous CHIKV clades as well as to other alphaviruses including Mayaro virus, O’nyong’nyong virus, and Una virus. Following heterologous infection with CHIKV-SL15649, HydroVax-CHIKV-immunized mice were protected against viremia, CHIKV-associated arthritic disease, and lethal CHIKV infection by an antibody-dependent mechanism. In contrast, animals vaccinated with Heat- or UV-inactivated virus showed no protection against viremia in addition to demonstrating significantly exacerbated CD4⁺ T cell-mediated footpad swelling after CHIKV infection. Together, these results demonstrate the risks associated with using suboptimal inactivation methods that fail to elicit protective neutralizing antibody responses and show that HydroVax-CHIKV represents a promising new vaccine candidate for prevention of CHIKV-associated disease.

Chikungunya virus (CHIKV) is a mosquito-borne virus that has gained significant attention due to its ability to cause large epidemics and to spread beyond endemic countries through international travelers. Despite substantial efforts over the course of many years, a licensed CHIKV vaccine remains unavailable for protecting at-risk populations. Our research group has established an advanced site-directed oxidation system, termed HydroVax, for the development of new vaccines. Here, we describe a novel CHIKV vaccine that utilizes this peroxide-based vaccine platform and demonstrates greatly improved antiviral immunity compared to other traditional virus inactivation approaches as well as complete protection against viremia, CHIKV-associated arthritic disease and lethal CHIKV infection in robust preclinical mouse models. The HydroVax-CHIKV vaccine not only induced neutralizing antibodies to geographically diverse strains of CHIKV, but also elicited neutralizing antibody responses to other clinically important alphaviruses including, Mayaro, O’nyong’nyong, and Una virus. Together, this indicates that this vaccine not only protects against CHIKV infection but may potentially provide immunity across a broader range of virulent alphaviruses as well.

A Novel Sphingosine Kinase Inhibitor Suppresses Chikungunya Virus Infection

Chikungunya virus (CHIKV) is a re-emerging arbovirus in the alphavirus genus. Upon infection, it can cause severe joint pain that can last years in some patients, significantly affecting their quality of life. Currently, there are no vaccines or anti-viral therapies available against CHIKV. Its spread to the Americas from the eastern continents has substantially increased the count of the infected by millions. Thus, there is an urgent need to identify therapeutic targets for CHIKV treatment. A potential point of intervention is the sphingosine-1-phosphate (S1P) pathway. Conversion of sphingosine to S1P is catalyzed by Sphingosine kinases (SKs), which we previously showed to be crucial pro-viral host factor during CHIKV infection. In this study, we screened inhibitors of SKs and identified a novel potent inhibitor of CHIKV infection—SLL3071511. We showed that the pre-treatment of cells with SLL3071511 in vitro effectively inhibited CHIKV infection with an EC50 value of 2.91 µM under both prophylactic and therapeutic modes, significantly decreasing the viral gene expression and release of viral particles. Our studies suggest that targeting SKs is a viable approach for controlling CHIKV replication.

A Review on Chikungunya Virus Epidemiology, Pathogenesis and Current Vaccine Development

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that recently re-emerged in many parts of the world causing large-scale outbreaks. CHIKV infection presents as a febrile illness known as chikungunya fever (CHIKF). Infection is self-limited and characterized mainly by severe joint pain and myalgia that can last for weeks or months; however, severe disease presentation can also occur in a minor proportion of infections. Among the atypical CHIKV manifestations that have been described, severe arthralgia and neurological complications, such as encephalitis, meningitis, and Guillain–Barré Syndrome, are now reported in many outbreaks. Moreover, death cases were also reported, placing CHIKV as a relevant public health disease. Virus evolution, globalization, and climate change may have contributed to CHIKV spread. In addition to this, the lack of preventive vaccines and approved antiviral treatments is turning CHIKV into a major global health threat. In this review, we discuss the current knowledge about CHIKV pathogenesis, with a focus on atypical disease manifestations, such as persistent arthralgia and neurologic disease presentation. We also bring an up-to-date review of the current CHIKV vaccine development. Altogether, these topics highlight some of the most recent advances in our understanding of CHIKV pathogenesis and also provide important insights into the current development and clinical trials of CHIKV potential vaccine candidates.

Immunological implications of diverse production approaches for Chikungunya virus-like particle vaccines

Chikungunya virus (CHIKV), an arbovirus from the Alphavirus genus, causes sporadic outbreaks and epidemics and can cause acute febrile illness accompanied by severe long-term arthralgias. Over 20 CHIKV vaccine candidates have been developed over the last two decades, utilizing a wide range of vaccine platforms, including virus-like particles (VLP). A CHIKV VLP vaccine candidate is among three candidates in late-stage clinical testing and has potentially promising data in nonclinical and clinical studies exploring safety and vaccine immunogenicity. Despite the consistency of the CHIKV VLP structure, vaccine candidates vary significantly in protein sequence identity, structural protein expression cassettes and their mode of production. Here, we explore the impact of CHIKV VLP coding sequence variation and the chosen expression platform, which affect VLP expression yields, antigenicity and overall vaccine immunogenicity. Additionally, we explore the potential of the CHIKV VLP platform to be modified to elicit protection against other pathogens.

Luciferase Immunosorbent Assay Based on Multiple E Antigens for the Detection of Chikungunya Virus-Specific IgG Antibodies

At present, chikungunya virus (CHIKV) is still circulating in some parts of the world, and mutated strains have emerged, making it easier for the virus to spread among humans. With the continuous variation of CHIKV, its antigen variation leads to the decline of detection ability.

Distinct Cellular Tropism and Immune Responses to Alphavirus Infection

Alphaviruses are emerging and reemerging viruses that cause disease syndromes ranging from incapacitating arthritis to potentially fatal encephalitis. While infection by arthritogenic and encephalitic alphaviruses results in distinct clinical manifestations, both virus groups induce robust innate and adaptive immune responses. However, differences in cellular tropism, type I interferon induction, immune cell recruitment, and B and T cell responses result in differential disease progression and outcome. In this review, we discuss aspects of immune responses that contribute to protective or pathogenic outcomes after alphavirus infection. Expected final online publication date for the Annual Review of Immunology, Volume 40 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Prevention of Emerging Infections in Children

Prevention of emerging infections in children is a dynamic arena where substantial medical advances have enabled intervention and prevention of infection outbreaks. This article discusses 5 infections causing significant morbidity and mortality across Asia, Latin America, and Africa. Avian influenza and the Middle East respiratory syndrome are highly contagious zoonoses spread through aerosol and droplets, affecting predominantly Asia. Dengue infection and chikungunya are endemic mosquito-borne viruses in tropical regions across Asia, Latin America, and Africa. Ebola is a highly contagious virus spread through human-to-human contact. The latest information in clinical manifestations, infection, prevention control, chemoprophylaxis, vaccination, and public health measures is reviewed.

Secreted Trimeric Chikungunya Virus Spikes from Insect Cells: Production, Purification, and Glycosylation Status

Chikungunya virus (CHIKV) is a rapidly emerging mosquito-borne virus that causes a severe febrile illness with long-lasting arthralgia in humans. As there is no vaccine to protect humans and limit CHIKV epidemics, the virus continues to be a global public health concern. The CHIKV envelope glycoproteins E1 and E2 are important immunogens; therefore, the aim of this study is to produce trimeric CHIKV spikes in insect cells using the baculovirus expression system. The CHIKV E1 and E2 ectodomains were covalently coupled by a flexible linker that replaces the 6K transmembrane protein. The C-terminal E1 transmembrane was replaced by a Strep-tag II for the purification of secreted spikes from the culture fluid. After production in Sf9 suspension cells (product yields of 5.8–7.6 mg/L), the CHIKV spikes were purified by Strep-Tactin affinity chromatography, which successfully cleared the co-produced baculoviruses. Bis(sulfosuccinimidyl)suberate cross-linking demonstrated that the spikes are secreted as trimers. PNGase F treatment showed that the spikes are glycosylated. LC–MS/MS-based glycoproteomic analysis confirmed the glycosylation and revealed that the majority are of the mannose- or hybrid-type N-glycans and <2% have complex-type N-glycans. The LC –MS/MS analysis also revealed three O-glycosylation sites in E1. In conclusion, the trimeric, glycosylated CHIKV spikes have been successfully produced in insect cells and are now available for vaccination studies.

Emerging Mosquito-Borne Viruses Linked to Aedes aegypti and Aedes albopictus: Global Status and Preventive Strategies

Emerging mosquito-borne viruses continue to cause serious health problems and economic burden among billions of people living in and near the tropical belt of the world. The highly invasive mosquito species Aedes aegypti and Aedes albopictus have successively invaded and expanded their presence as key vectors of Chikungunya virus, dengue virus, yellow fever virus, and Zika virus, and that has consecutively led to frequent outbreaks of the corresponding viral diseases. Of note, these two mosquito species have gradually adapted to the changing weather and environmental conditions leading to a shift in the epidemiology of the viral diseases, and facilitated their establishment in new ecozones inhabited by immunologically naive human populations. Many abilities of Ae. aegypti and Ae. albopictus, as vectors of significant arbovirus pathogens, may affect the infection and transmission rates after a bloodmeal, and may influence the vector competence for either virus. We highlight that many collaborating risk factors, for example, the global transportation systems may result in sporadic and more local outbreaks caused by mosquito-borne viruses related to Ae. aegypti and/or Ae. albopictus. Those local outbreaks could in synergy grow and produce larger epidemics with pandemic characters. There is an urgent need for improved surveillance of vector populations, human cases, and reliable prediction models. In summary, we recommend new and innovative strategies for the prevention of these types of infections.

Potential SARS-CoV-2 vaccines: Concept, progress, and challenges

Since September 2020, the world has had more than 28 million cases of coronavirus disease 2019 (COVID-19). Many countries are facing a second wave of the COVID-19 outbreak. A pressing need is evident for the development of a potent vaccine to control the SARS-CoV-2. Institutions and companies in many countries have announced their vaccine research programs and progress against the COVID-19. While most vaccines go through the designation and preparation stages, some of them are under evaluation for efficacy among animal models and clinical trials, and three approved vaccine candidates have been introduced for limited exploitation in Russia and China. An effective vaccine must induce a protective response of both cell-mediated and humoral immunity and should meet the safety and efficacy criteria. Although the emergence of new technologies has accelerated the development of vaccines, there are several challenges on the way, such as limited knowledge about the pathophysiology of the virus, inducing humoral or cellular immunity, immune enhancement with animal coronavirus vaccines, and lack of an appropriate animal model. In this review, we firstly discuss the immune responses against SARS-CoV-2 disease, subsequently, give an overview of several vaccine platforms for SARS-CoV-2 under clinical trials and challenges in vaccine development against this virus.

Specific Recognition of a Stem-Loop RNA Structure by the Alphavirus Capsid Protein

Alphaviruses are small enveloped viruses with positive-sense RNA genomes. During infection, the alphavirus capsid protein (Cp) selectively packages and assembles with the viral genomic RNA to form the nucleocapsid core, a process critical to the production of infectious virus. Prior studies of the alphavirus Semliki Forest virus (SFV) showed that packaging and assembly are promoted by Cp binding to multiple high affinity sites on the genomic RNA. Here, we developed an in vitro Cp binding assay based on fluorescently labeled RNA oligos. We used this assay to explore the RNA sequence and structure requirements for Cp binding to site #1, the top binding site identified on the genomic RNA during all stages of virus assembly. Our results identify a stem-loop structure that promotes specific binding of the SFV Cp to site #1 RNA. This structure is also recognized by the Cps of the related alphaviruses chikungunya virus and Ross River virus.

A single dose of ChAdOx1 Chik vaccine induces neutralizing antibodies against four chikungunya virus lineages in a phase 1 clinical trial

Chikungunya virus (CHIKV) is a reemerging mosquito-borne virus that causes swift outbreaks. Major concerns are the persistent and disabling polyarthralgia in infected individuals. Here we present the results from a first-in-human trial of the candidate simian adenovirus vectored vaccine ChAdOx1 Chik, expressing the CHIKV full-length structural polyprotein (Capsid, E3, E2, 6k and E1). 24 adult healthy volunteers aged 18-50 years, were recruited in a dose escalation, open-label, nonrandomized and uncontrolled phase 1 trial (registry NCT03590392). Participants received a single intramuscular injection of ChAdOx1 Chik at one of the three preestablished dosages and were followed-up for 6 months. The primary objective was to assess safety and tolerability of ChAdOx1 Chik. The secondary objective was to assess the humoral and cellular immunogenicity. ChAdOx1 Chik was safe at all doses tested with no serious adverse reactions reported. The vast majority of solicited adverse events were mild or moderate, and self-limiting in nature. A single dose induced IgG and T-cell responses against the CHIKV structural antigens. Broadly neutralizing antibodies against the four CHIKV lineages were found in all participants and as early as 2 weeks after vaccination. In summary, ChAdOx1 Chik showed excellent safety, tolerability and 100% PRNT₅₀ seroconversion after a single dose.

Contribution of Research in the West Indies and Northeast Amazonia to Knowledge of the 2014-2015 Chikungunya Epidemic in the Americas

Purpose of Review

Although the chikungunya virus was discovered more than 60 years ago, it has only really been studied since the outbreak in La Reunion in 2005-2006. Ten years later, between 2014 and 2015, the chikungunya virus spread throughout the Americas, affecting millions of people. The objective of this review is to describe the contributions of research on chikungunya virus infection gained from epidemic in the West Indies and the Guiana Shield.

Recent Findings

Prevalence data were similar to those found in the Indian Ocean or Asia during epidemics. Clinically, there is now a better understanding of the typical, atypical, and severe forms. Several studies have insisted on the presence of neurological forms of chikungunya infection, such as encephalitis or Guillain-Barré syndrome. Cases of septic shock due to chikungunya virus as well as thrombotic thrombocytopenic purpura were described for the first time. Given the magnitude of the epidemic and the large number of people affected, this has led to a better description and new classifications of chikungunya virus infections in specific populations such as pregnant women, the elderly, and children. Several studies also described the behavior of populations faced with an emerging disease.

Summary

Current epidemiological data from tropical regions highlights the risk of spreading emerging diseases at higher latitudes, especially concerning arboviruses, since the vector Aedes albopictus is already established in many parts of northern countries. A better understanding of the disease and its epidemic dynamics will foster better management, the crucial importance of which was demonstrated during the COVID-19 epidemic.

Insights into Antibody-Mediated Alphavirus Immunity and Vaccine Development Landscape

Alphaviruses are mosquito-borne pathogens distributed worldwide in tropical and temperate areas causing a wide range of symptoms ranging from inflammatory arthritis-like manifestations to the induction of encephalitis in humans. Historically, large outbreaks in susceptible populations have been recorded followed by the development of protective long-lasting antibody responses suggesting a potential advantageous role for a vaccine. Although the current understanding of alphavirus antibody-mediated immunity has been mainly gathered in natural and experimental settings of chikungunya virus (CHIKV) infection, little is known about the humoral responses triggered by other emerging alphaviruses. This knowledge is needed to improve serology-based diagnostic tests and the development of highly effective cross-protective vaccines. Here, we review the role of antibody-mediated immunity upon arthritogenic and neurotropic alphavirus infections, and the current research efforts for the development of vaccines as a tool to control future alphavirus outbreaks.

Persistent Joint Pain Following Arthropod Virus Infections

PURPOSE OF REVIEW

Persistent joint pain is a common manifestation of arthropod-borne viral infections and can cause long-term disability. We review the epidemiology, pathophysiology, diagnosis, and management of arthritogenic alphavirus infection.

RECENT FINDINGS

The global re-emergence of alphaviral outbreaks has led to an increase in virus-induced arthralgia and arthritis. Alphaviruses, including Chikungunya, O'nyong'nyong, Sindbis, Barmah Forest, Ross River, and Mayaro viruses, are associated with acute and/or chronic rheumatic symptoms. Identification of Mxra8 as a viral entry receptor in the alphaviral replication pathway creates opportunities for treatment and prevention. Recent evidence suggesting virus does not persist in synovial fluid during chronic chikungunya infection indicates that immunomodulators may be given safely. The etiology of persistent joint pain after alphavirus infection is still poorly understood. New diagnostic tools along and evidence-based treatment could significantly improve morbidity and long-term disability.

Design of Alphavirus Virus-Like Particles Presenting Circumsporozoite Junctional Epitopes That Elicit Protection against Malaria

The most advanced malaria vaccine, RTS,S, includes the central repeat and C-terminal domains of the Plasmodium falciparum circumsporozoite protein (PfCSP). We have recently isolated human antibodies that target the junctional region between the N-terminal and repeat domains that are not included in RTS,S. Due to the fact that these antibodies protect against malaria challenge in mice, their epitopes could be effective vaccine targets. Here, we developed immunogens displaying PfCSP junctional epitopes by genetic fusion to either the N-terminus or B domain loop of the E2 protein from chikungunya (CHIK) alphavirus and produced CHIK virus-like particles (CHIK-VLPs). The structural integrity of these junctional-epitope-CHIK-VLP immunogens was confirmed by negative-stain electron microscopy. Immunization of these CHIK-VLP immunogens reduced parasite liver load by up to 95% in a mouse model of malaria infection and elicited better protection than when displayed on keyhole limpet hemocyanin, a commonly used immunogenic carrier. Protection correlated with PfCSP serum titer. Of note, different junctional sequences elicited qualitatively different reactivities to overlapping PfCSP peptides. Overall, these results show that the junctional epitopes of PfCSP can induce protective responses when displayed on CHIK-VLP immunogens and provide a basis for the development of a next generation malaria vaccine to expand the breadth of anti-PfCSP immunity.

Perspectives on New Vaccines against Arboviruses Using Insect-Specific Viruses as Platforms

Arthropod-borne viruses (arboviruses) are global pathogens circulating endemically with local explosive outbreaks and constant encroachment into new locations. Few vaccines against arboviruses exist; most for humans are in development or clinical trials. Insect-specific viruses (ISVs) offer a unique platform for expression of arbovirus proteins, through the creation of ISV/arbovirus chimeras. Studies have shown promising results of these vaccines with several advantages over their wild-type counterparts. In this review, we discuss the current status of these potential vaccines using ISVs.

Scaling up of Eco-Bio-Social Strategy to Control Aedes aegypti in Highly Vulnerable Areas in Fortaleza, Brazil: A Cluster, Non-Randomized Controlled Trial Protocol

Aedes aegypti is a cosmopolitan vector for arboviruses dengue, Zika and chikungunya, disseminated in all Brazilian states. The Eco-Bio-Social (EBS) strategy is vital in Aedes aegypti control as it mobilizes stakeholders (government, professionals, society, and academics) to promote healthy environments. This paper describes the rationale and methods of expanding the EBS strategy for Aedes aegypti control in Fortaleza, Northeast Brazil. A cluster, non-randomized controlled clinical trial was developed to analyze the strategy’s effectiveness in vulnerable territories (high incidence of dengue and violent deaths; low HDI; substandard urban infrastructure, high population density, and water scarcity). We selected two intervention and two control groups, resulting in a sample of approximately 16,000 properties. The intervention consisted of environmental management by sealing large elevated water tanks, introduction of beta fish in waterholes, elimination of potential breeding sites, and mobilization and training of schoolchildren, endemic disease workers, health workers, social mobilizers, and community leaders; community surveillance of arboviruses; construction and validation of a booklet for the prevention of arboviruses in pregnant women. We analyzed the costs of arboviruses to government and households, the intervention cost-effectiveness, chikungunya’s chronicity, and acceptance, sustainability, and governance of vector control actions. The primary outcome (infestation) was analyzed using the house, container, and Breteau indices. We hope that this study will help us understand how to scale up strategies to fight Aedes aegypti in vulnerable areas.

A phase 1 trial of lipid-encapsulated mRNA encoding a monoclonal antibody with neutralizing activity against Chikungunya virus

Chikungunya virus (CHIKV) infection causes acute disease characterized by fever, rash and arthralgia, which progresses to severe and chronic arthritis in up to 50% of patients. Moreover, CHIKV infection can be fatal in infants or immunocompromised individuals and has no approved therapy or prevention. This phase 1, first-in-human, randomized, placebo-controlled, proof-of-concept trial conducted from January 2019 to June 2020 evaluated the safety and pharmacology of mRNA-1944, a lipid nanoparticle-encapsulated messenger RNA encoding the heavy and light chains of a CHIKV-specific monoclonal neutralizing antibody, CHKV-24 ( NCT03829384 ). The primary outcome was to evaluate the safety and tolerability of escalating doses of mRNA-1944 administered via intravenous infusion in healthy participants aged 18-50 years. The secondary objectives included determination of the pharmacokinetics of mRNA encoding for CHKV-24 immunoglobulin heavy and light chains and ionizable amino lipid component and the pharmacodynamics of mRNA-1944 as assessed by serum concentrations of mRNA encoding for CHKV-24 immunoglobulin G (IgG), plasma concentrations of ionizable amino lipid and serum concentrations of CHKV-24 IgG. Here we report the results of a prespecified interim analysis of 38 healthy participants who received intravenous single doses of mRNA-1944 or placebo at 0.1, 0.3 and 0.6 mg kg^-1, or two weekly doses at 0.3 mg kg^-1. At 12, 24 and 48 h after single infusions, dose-dependent levels of CHKV-24 IgG with neutralizing activity were observed at titers predicted to be therapeutically relevant concentrations (≥1 µg ml^-1) across doses that persisted for ≥16 weeks at 0.3 and 0.6 mg kg^-1 (mean t_1/2 approximately 69 d). A second 0.3 mg kg^-1 dose 1 week after the first increased CHKV-24 IgG levels 1.8-fold. Adverse effects were mild to moderate in severity, did not worsen with a second mRNA-1944 dose and none were serious. To our knowledge, mRNA-1944 is the first mRNA-encoded monoclonal antibody showing in vivo expression and detectable ex vivo neutralizing activity in a clinical trial and may offer a treatment option for CHIKV infection. Further evaluation of the potential therapeutic use of mRNA-1944 in clinical trials for the treatment of CHIKV infection is warranted.

The Role of Virus-Like Particles in Medical Biotechnology

Virus-like particles (VLPs) are protein-based, nanoscale, self-assembling, cage architectures, which have relevant applications in biomedicine. They can be used for the development of vaccines, imaging approaches, drug and gene therapy delivery systems, and in vitro diagnostic methods. Today, three relevant viruses are targeted using VLP-based recombinant vaccines. VLP-based drug delivery, nanoreactors for therapy, and imaging systems are approaches under development with promising outcomes. Several VLP-based vaccines are under clinical evaluation. Herein, an updated view on the VLP-based biomedical applications is provided; advanced methods for the production, functionalization, and drug loading of VLPs are described, and perspectives for the field are identified.