Construction and immunogenicity of an mRNA vaccine against chikungunya virus.

Chikungunya fever (CHIKF) has spread to more than 100 countries worldwide, with frequent outbreaks in Europe and the Americas in recent years. Despite the relatively low lethality of infection, patients can suffer from long-term sequelae. Until now, no available vaccines have been approved for use; however, increasing attention is being paid to the development of vaccines against chikungunya virus (CHIKV), and the World Health Organization has included vaccine development in the initial blueprint deliverables. Here, we developed an mRNA vaccine using the nucleotide sequence encoding structural proteins of CHIKV. And immunogenicity was evaluated by neutralization assay, Enzyme-linked immunospot assay and Intracellular cytokine staining. The results showed that the encoded proteins elicited high levels of neutralizing antibody titers and T cell-mediated cellular immune responses in mice. Moreover, compared with the wild-type vaccine, the codon-optimized vaccine elicited robust CD8+ T-cell responses and mild neutralizing antibody titers. In addition, higher levels of neutralizing antibody titers and T-cell immune responses were obtained using a homologous booster mRNA vaccine regimen of three different homologous or heterologous booster immunization strategies. Thus, this study provides assessment data to develop vaccine candidates and explore the effectiveness of the prime-boost approach.

ChikvInt: a Chikungunya virus-host protein-protein interaction database.

Chikungunya is a fast-mutating virus causing Chikungunya virus disease (ChikvD) with a significant load of disability-adjusted life years (DALY) around the world. The outbreak of this virus is significantly higher in the tropical countries. Several experiments have identified crucial viral-host protein-protein interactions (PPIs) between Chikungunya Virus (Chikv) and the human host. However, no standard database that catalogs this PPI information exists. Here we develop a Chikv-Human PPI database, ChikvInt, to facilitate understanding ChikvD disease pathogenesis and the progress of vaccine studies. ChikvInt consists of 109 interactions and is available at www.chikvint.com.

In Depth Viral Diversity Analysis in Atypical Neurological and Neonatal Chikungunya Infections in Rio de Janeiro, Brazil.

Chikungunya virus (CHIKV) is an arthropod-borne virus (arbovirus) transmitted by Aedes mosquitoes. The human infection usually manifests as a febrile and incapacitating arthritogenic illness, self-limiting and non-lethal. However, since 2013, CHIKV spreading through the tropics and to the Americas was accompanied by an increasing number of cases of atypical disease presentation, namely severe neuropathies and neonatal infection due to intrapartum vertical transmission. The pathophysiological mechanisms underlying these conditions have not been fully elucidated. However, arbovirus intrahost genetic diversity is thought to be linked to viral pathogenesis. To determine whether particular viral variants could be somehow associated, we analyzed the intrahost genetic diversity of CHIKV in three infected patients with neurological manifestations and three mothers infected during the intrapartum period, as well as their babies following vertical transmission. No statistically supported differences were observed for the genetic variability (nucleotide substitutions/gene length) along the genome between the groups. However, the newborn and cerebrospinal fluid samples (corresponding to virus passed through the placenta and/or the blood-brain barrier (BBB)) presented a different composition of their intrahost mutant ensembles compared to maternal or patient serum samples, even when concurrent. This finding could be consistent with the unidirectional virus transmission through these barriers, and the effect of selective bottlenecks during the transmission event. In addition, a higher proportion of defective variants (insertions/deletions and stop codons) was detected in the CSF and maternal samples and those were mainly distributed within the viral non-structural genes. Since defective viral genomes in RNA viruses are known to contribute to the outcome of acute viral infections and influence disease severity, their role in these atypical cases should be further investigated. Finally, with the in silico approach adopted, we detected no relevant non-conservative mutational pattern that could provide any hint of the pathophysiological mechanisms underlying these atypical cases. The present analysis represents a unique contribution to our understanding of the transmission events in these cases and generates hypotheses regarding underlying mechanisms, that can be explored further.

Overlap between dengue, Zika and chikungunya hotspots in the city of Rio de Janeiro.

BACKGROUND: Arboviruses represent a threat to global public health. In the Americas, the dengue fever is endemic. This situation worsens with the introduction of emerging, Zika fever and chikungunya fever, causing epidemics in several countries within the last decade. Hotspot analysis contributes to understanding the spatial and temporal dynamics in the context of co-circulation of these three arboviral diseases, which have the same vector: Aedes aegypti. OBJECTIVE: To analyze the spatial distribution and agreement between the hotspots of the historical series of reported dengue cases from 2000 to 2014 and the Zika, chikungunya and dengue cases hotspots from 2015 to 2019 in the city of Rio de Janeiro. METHODS: To identify hotspots, Gi* statistics were calculated for the annual incidence rates of reported cases of dengue, Zika, and chikungunya by neighborhood. Kendall's W statistic was used to analyze the agreement between diseases hotspots. RESULTS: There was no agreement between the hotspots of the dengue fever historical series (2000-2014) and those of the emerging Zika fever and chikungunya fever (2015-2019). However, there was agreement between hotspots of the three arboviral diseases between 2015 and 2019. CONCLUSION: The results of this study show the existence of persistent hotspots that need to be prioritized in public policies for the prevention and control of these diseases. The techniques used with data from epidemiological surveillance services can help in better understanding of the dynamics of these diseases wherever they circulate in the world.

A syntenin inhibitor blocks endosomal entry of SARS-CoV-2 and a panel of RNA viruses (preprint)

Viruses are dependent on interactions with host factors in order to efficiently establish an infection and replicate. Targeting such interactions provides an attractive strategy to develop novel antivirals. Syntenin is a protein known to regulate the architecture of cellular membranes by its involvement in protein trafficking, and has previously been shown to be important for HPV infection. Here we show that a highly potent and metabolically stable peptide inhibitor that binds to the PDZ1 domain of syntenin inhibits SARS-CoV-2 infection by blocking the endosomal entry of the virus. Furthermore, we found that the inhibitor also hampered chikungunya infection, and strongly reduced flavivirus infection, which are completely dependent on receptor mediated endocytosis for their entry. In conclusion, we have identified a novel pan-viral inhibitor that efficiently target a broad range of RNA viruses.

A Brighton Collaboration standardized template with key considerations for a benefit/risk assessment for an inactivated viral vaccine against Chikungunya virus.

Inactivated viral vaccines have long been used in humans for diseases of global health threat (e.g., poliomyelitis and pandemic and seasonal influenza) and the technology of inactivation has more recently been used for emerging diseases such as West Nile, Chikungunya, Ross River, SARS and especially for COVID-19. The Brighton Collaboration Benefit-Risk Assessment of VAccines by TechnolOgy (BRAVATO) Working Group has prepared standardized templates to describe the key considerations for the benefit and risk of several vaccine platform technologies, including inactivated viral vaccines. This paper uses the BRAVATO inactivated virus vaccine template to review the features of an inactivated whole chikungunya virus (CHIKV) vaccine that has been evaluated in several preclinical studies and clinical trials. The inactivated whole CHIKV vaccine was cultured on Vero cells and inactivated by ß-propiolactone. This provides an effective, flexible system for high-yield manufacturing. The inactivated whole CHIKV vaccine has favorable thermostability profiles, compatible with vaccine supply chains. Safety data are compiled in the current inactivated whole CHIKV vaccine safety database with unblinded data from the ongoing studies: 850 participants from phase II study (parts A and B) outside of India, and 600 participants from ongoing phase II study in India, and completed phase I clinical studies for 60 subjects. Overall, the inactivated whole CHIKV vaccine has been well tolerated, with no significant safety issues identified. Evaluation of the inactivated whole CHIKV vaccine is continuing, with 1410 participants vaccinated as of 20 April 2022. Extensive evaluation of immunogenicity in humans shows strong, durable humoral immune responses.

The Tetraspanin CD81 Is a Host Factor for Chikungunya Virus Replication.

Chikungunya virus (CHIKV) is an arthritogenic reemerging virus replicating in plasma membrane-derived compartments termed "spherules." Here, we identify the human transmembrane protein CD81 as host factor required for CHIKV replication. Ablation of CD81 results in decreased CHIKV permissiveness, while overexpression enhances infection. CD81 is dispensable for virus uptake but critically required for viral genome replication. Likewise, murine CD81 is crucial for CHIKV permissiveness and is expressed in target cells such as dermal fibroblasts, muscle and liver cells. Whereas related alphaviruses, including Ross River virus (RRV), Semliki Forest virus (SFV), Sindbis virus (SINV) and Venezuelan equine encephalitis virus (VEEV), also depend on CD81 for infection, RNA viruses from other families, such as coronaviruses, replicate independently of CD81. Strikingly, the replication-enhancing function of CD81 is linked to cholesterol binding. These results define a mechanism exploited by alphaviruses to hijack the membrane microdomain-modeling protein CD81 for virus replication through interaction with cholesterol. IMPORTANCE In this study, we discover the tetraspanin CD81 as a host factor for the globally emerging chikungunya virus and related alphaviruses. We show that CD81 promotes replication of viral genomes in human and mouse cells, while virus entry into cells is independent of CD81. This provides novel insights into how alphaviruses hijack host proteins to complete their life cycle. Alphaviruses replicate at distinct sites of the plasma membrane, which are enriched in cholesterol. We found that the cholesterol-binding ability of CD81 is important for its function as an alphavirus host factor. This discovery thus broadens our understanding of the alphavirus replication process and the use of host factors to reprogram cells into virus replication factories.

Detection of SARS-CoV-2 antibodies in febrile patients from an endemic region of dengue and chikungunya in Peru.

INTRODUCTION: The rapid expansion of the novel SARS-CoV-2 virus has raised serious public health concerns due to the possibility of misdiagnosis in regions where arboviral diseases are endemic. We performed the first study in northern Peru to describe the detection of SARS-CoV-2 IgM antibodies in febrile patients with a suspected diagnosis of dengue and chikungunya fever. MATERIALS AND METHODS: A consecutive cross-sectional study was performed in febrile patients attending primary healthcare centers from April 2020 through March 2021. Patients enrolled underwent serum sample collection for the molecular and serological detection of DENV and CHIKV. Also, serological detection of IgM antibodies against SARS-CoV-2 was performed. RESULTS: 464 patients were included during the study period, of which (40.51%) were positive for one pathogen, meanwhile (6.90%) presented co-infections between 2 or more pathogens. The majority of patients with monoinfections were positive for SARS-CoV-2 IgM with (73.40%), followed by DENV 18.09% and CHIKV (8.51%). The most frequent co-infection was DENV + SARS-CoV-2 with (65.63%), followed by DENV + CHIKV and DENV + CHIKV + SARS-CoV-2, both with (12.50%). The presence of polyarthralgias in hands (43.75%, p<0.01) and feet (31.25%, p = 0.05) were more frequently reported in patients with CHIKV monoinfection. Also, conjunctivitis was more common in patients positive for SARS-CoV-2 IgM (11.45%, p<0.01). The rest of the symptoms were similar among all the study groups. CONCLUSION: SARS-CoV-2 IgM antibodies were frequently detected in acute sera from febrile patients with a clinical suspicion of arboviral disease. The presence of polyarthralgias in hands and feet may be suggestive of CHIKV infection. These results reaffirm the need to consider SARS-CoV-2 infection as a main differential diagnosis of acute febrile illness in arboviruses endemic areas, as well as to consider co-infections between these pathogens.

A virus like particle approach to study the Chikungunya virus envelope protein mutations.

Virus like particles (VLPs) are used as a tool to study the mutations in the structural genes that influence the virus assembly and entry process. We observed that Chikungunya VLP with the E1:V291I mutation produced more fluorescence-positive cells in Vero cells than the other mutant VLPs (E1:A226V, D284E, and E2:V264A) and wild-type VLP tested in this study. According to the findings, the V291I mutation may aid the virus's ability to enter the cells more efficiently than wild-type VLPs. The study concludes that VLP is a useful model for studying the virus entry process in cells.

Mayaro virus infection in French Guiana, a cross sectional study 2003-2019.

Mayaro Virus is an emerging arbovirus which can be responsible of important outbreaks in tropical regions. A retrospective study was performed in French Guiana, an ultraperipheral region of Europe in Amazonia. We identified 17 human cases between 2003 and 2019. The clinical and biological picture was close to Chikungunya with fever and arthralgia. One patient had acute meningo-encephalitis, and 4 had persistent arthralgia. Physicians should be aware of this virus, as imported cases in Europe have already occurred. AUTHOR SUMMARY: Latin America has experienced several epidemics of arboviruses in recent years, some known for a long time, such as the dengue virus, and others of more recent introduction such as the chikungunya or Zika viruses. There are other arboviruses for the moment more discreet which are rife with low noise in several countries of the continent, such as the Mayaro virus. This alphavirus, with a presentation similar to that of the chikungunya virus, is currently confined to transmission by forest mosquitoes, but its potential to be transmitted by coastal mosquitoes such as Aedes aegypti, make it a potential candidate for a continent-wide epidemic. It therefore seems necessary to know this virus as well as possible in order to anticipate the occurrence of a possible new epidemic. We present here a both demographic and clinical study of this endemic arbovirus disease in French Guiana.

Emerging tropical neurological infections.

A large majority of neurological infections remain undiagnosed worldwide. Emerging and re-emerging infections are likely to be responsible for a significant proportion of these. Over the last two decades, several new organisms producing neurological infection and the neurotropic potential of many other known pathogens have been identified. Large outbreaks caused by re-emerging pathogens such as Chikungunya virus, Zika virus and Ebola virus have led to better delineation of their neurological manifestations. Recognition of the pandemic potential of emerging pathogens and an improved understanding of their host-vector-environment interactions would help us be better prepared to meet these emerging threats.

Aedes mosquitoes in the emerging threat of urban yellow fever transmission.

This last decade has seen a resurgence of yellow fever (YF) in historical endemic regions and repeated attempts of YF introduction in YF-free countries such as the Asia-Pacific region and the Caribbean. Infected travellers are the main entry routes in these regions where competent mosquito vectors proliferate in appropriate environmental conditions. With the discovery of the 17D vaccine, it was thought that YF would be eradicated. Unfortunately, it was not the case and, contrary to dengue, chikungunya and Zika, factors that cotribute to YF transmission remain under investigation. Today, all the signals are red and it is very likely that YF will be the next pandemic in the YF-free regions where millions of people are immunologically naïve. Unlike COVID-19, YF is associated with a high case-fatality rate and a high number of deaths are expected. This review gives an overview of global YF situation, including the non-endemic Asia-Pacific region and the Caribbean where Aedes aegypti is abundantly distributed, and also proposes different hypotheses on why YF outbreaks have not yet occurred despite high records of travellers importing YF into these regions and what role Aedes mosquitoes play in the emergence of urban YF.

Evidence of Coinfections between SARS-CoV-2 and Select Arboviruses in Guerrero, Mexico, 2020-2021.

We provide evidence of concurrent and close sequential infections between SARS-CoV-2 and select arboviruses-namely, chikungunya virus (CHIKV); dengue viruses 1, 2, and 3 (DENV1-3), and Zika virus (ZIKV)-in patients in Guerrero, southwest Mexico, in 2020-2021. The study population consisted of 176 febrile patients with laboratory evidence of SARS-CoV-2 infection. Sera from all patients were serologically and antigenically tested for seven arboviruses known to occur in Guerrero. Eighteen patients contained CHIKV IgM, six of whom also contained CHIKV RNA. Another 16 patients contained flavivirus antigen. The flaviviruses responsible for the infections were identified by plaque reduction neutralization test as DENV1 (two patients), DENV2 (five patients), DENV3 (three patients), ZIKV (three patients), and an undetermined flavivirus (three patients). In summary, we identified patients in Guerrero, Mexico, with concurrent or recent sequential infections between SARS-CoV-2 and select arboviruses, exemplifying the importance of performing differential diagnosis in regions where these viruses cocirculate.

Neurological infection by chikungunya and a triple Arbovirus co-infection in Mato Grosso, Central Western Brazil during 2019.

BACKGROUND: Neurological viral infection is frequently associated to enterovirus, herpesvirus and arboviruses. These infections may cause severe clinical outcomes, long lasting sequelae or death. Few studies have addressed viral neurological infections etiology in Brazil. OBJECTIVES: Identification of viruses in the cerebral spinal fluid (CSF) of human neurological infections suspected of viral etiology during January and May 2019 in Midwestern Brazil. MATERIALS AND METHODS: Clinical, laboratory and epidemiological information was gathered from medical records. In addition, an aliquot of the sampled CSF was subjected to viral RNA/DNA extraction, randomic dscDNA amplification by PCR, DNA purification and Ilumina HiSeq 2500 sequencing. RESULTS: Six viral genomes belonging to Chikungunya virus (CHIKV) East-Central-South African (ECSA) genotype (10.834-11.804 nt in length) confirmed lately by RT-PCR for CHIKV envelope were present in all six liquor samples. These genomes present two mutations, nsP2:T31I and nsP3:A388V, shared with other Mato Grosso State strains from 2019, not present in sequences of the virus from previous years obtained in the State. One case was a triple co-infection also confirmed through RT-PCR, with Dengue virus serotype 4 genotype II (NS5; 874 nt) and Oropouche virus genotype IA (segment S; 302 nt). CSF was clear and colorless (5/6 patients), with >10% of lymphomononuclear cells (6/6), 1-99 erythrocytes/mm3 (5/6), glucose levels >50 mg/dl (4/5) e > 10 mg/dl of proteins (4/4). One patient evolved to death, and another, a newborn, presented sequelae after recovery. CONCLUSIONS: Despite herpesviruses and enteroviruses are frequent etiologies of neurological infections, the casuistic here reported was associated to arboviruses already known to be responsible for acute febrile illness outbreaks in the state of Mato Grosso, Midwestern Brazil.

Coinfection between SARS-CoV-2 and vector-borne diseases in Luanda, Angola.

Co-epidemics happening simultaneously can generate a burden on healthcare systems. The co-occurrence of SARS-CoV-2 with vector-borne diseases (VBD), such as malaria and dengue in resource-limited settings represents an additional challenge to the healthcare systems. Herein, we assessed the coinfection rate between SARS-CoV-2 and VBD to highlight the need to carry out an accurate diagnosis and promote timely measures for these infections in Luanda, the capital city of Angola. This was a cross-sectional study conducted with 105 subjects tested for the SARS-CoV-2 and VBD with a rapid detection test in April 2021. The participants tested positive for SARS-CoV-2 (3.80%), malaria (13.3%), and dengue (27.6%). Low odds related to testing positivity to SARS-CoV-2 or VBD were observed in participants above or equal to 40 years (odds ratio [OR]: 0.60, p = 0.536), while higher odds were observed in male (OR: 1.44, p = 0.392) and urbanized areas (OR: 3.78, p = 0.223). The overall co-infection rate between SARS-CoV-2 and VBD was 11.4%. Our findings showed a coinfection between SARS-CoV-2 with malaria and dengue, which could indicate the need to integrate the screening for VBD in the SARS-CoV-2 testing algorithm and the adjustment of treatment protocols. Further studies are warranted to better elucidate the relationship between COVID-19 and VBD in Angola.

Source-tracking of the Chinese Chikungunya viruses suggests that Indian subcontinent and Southeast Asia act as major hubs for the recent global spread of Chikungunya virus.

BACKGROUND: Chikungunya fever, caused by the Chikungunya virus (CHIKV), has become a major global health concern, causing unexpected large outbreaks in Africa, Asia, Europe, and the Americas. CHIKV is not indigenous to China, and its origin in the country is poorly understood. In particular, there is limited understanding of the recent global spread of CHIKV in the context of the CHIKV epidemic. METHODS: Here we investigated a novel Chikungunya patient who came from Myanmar to China in August, 2019. Direct genome sequencing was performed via combined MinION sequencing and BGISEQ-500 sequencing. A complete CHIKV genome dataset, including 727 CHIKV genomes retrieved from GenBank and the genome sequenced in this study, was constructed. An updated and comprehensive phylogenetic analysis was conducted to understand the virus's origin, evolution, transmission routes and genetic adaptation. RESULTS: All globally distributed CHIKV genomes were divided into West Africa, East/Central/South African and Asian genotypes. The genome sequenced in this study was located in the Indian Ocean lineage, and was closely related to a strain isolated from an Australian patient who returned from Bangladesh in 2017. A comprehensive phylogenetic analysis showed that the Chinese strains mainly originated from the Indian subcontinent and Southeast Asia. Further analyses indicated that the Indian subcontinent and Southeast Asia may act as major hubs for the recent global spread of CHIKV, leading to multiple outbreaks and epidemics. Moreover, we identified 179 distinct sites, including some undescribed sites in the structural and non-structural proteins, which exhibited apparent genetic variations associated with different CHIKV lineages. CONCLUSIONS: Here we report a novel CHIKV isolate from a chikungunya patient who came from Myanmar to China in 2019, and summarize the source and evolution of Chinese CHIKV strains. Our present findings provide a better understanding of the recent global evolution of CHIKV, highlighting the urgent need for strengthened surveillance against viral diversity.

Sulfasalazine-induced drug reaction with eosinophilia and systemic symptoms (DRESS) with concomitant acute chikungunya virus infection: possible role of new viral trigger.

Drug reaction with eosinophilia and systemic symptoms (DRESS) is designated as a potentially lethal adverse drug effect with characteristic signs and symptoms such as skin rash, fever, leucocytosis with eosinophilia or atypical lymphocytes, lymphadenopathy and liver or renal dysfunction. In addition to most commonly implicated drug category (aromatic anticonvulsants), lamotrigine, sulfonamides, dapsone and abacavir may also induce this syndrome. We describe here a case a sulfasalazine-induced DRESS with coexisting chikungunya fever. The shared presentation of fever with rash in both conditions made it a challenging diagnosis. Sulfasalazine hypersensitivity manifesting as DRESS has rarely been reported. Furthermore, we document chikungunya virus (CV) as a possible triggering agent for DRESS. To the best of our knowledge, CV as a viral aetiology in DRESS has not been reported previously in the literature.