Global expansion of chikungunya virus: mapping the 64-year history

The Midgut Microbiota of Colombian Aedes aegypti Populations with Different Levels of Resistance to the Insecticide Lambda-cyhalothrin

Insecticide resistance in Aedes aegypti populations is a problem that hinders vector control and dengue prevention programs. In this study, we determined the susceptibility of Ae. aegypti populations from six Colombian regions to the pyrethroid lambda-cyhalothrin and evaluated the presence of the V1016I mutation in the sodium channel gene, which has been broadly involved in the resistance to this insecticide. The diversity of the gut microbiota of these mosquito populations was also analyzed. Only mosquitoes from Bello were susceptible to lambda-cyhalothrin and presented a lower allelic frequency of the V1016I mutation. Remarkably, there was not an important change in allelic frequencies among populations with different resistance ratios, indicating that other factors or mechanisms contributed to the resistant phenotype. Treatment of mosquitoes with antibiotics led us to hypothesize that the intestinal microbiota could contribute to the resistance to lambda-cyhalothrin. Beta diversity analysis showed significant differences in the species of bacteria present between susceptible and resistant populations. We identified 14 OTUs of bacteria that were unique in resistant mosquitoes. We propose that kdr mutations are important in the development of resistance to lambda-cyhalothrin at low insecticide concentrations but insect symbionts could play an essential role in the metabolization of pyrethroid insecticides at higher concentrations, contributing to the resistant phenotype in Ae. aegypti.

Harnessing Dengue Rapid Diagnostic Tests for the Combined Surveillance of Dengue, Zika, and Chikungunya Viruses in Laos

Recent expansions of vector-borne diseases highlight the need for improved surveillance, especially in resource-poor settings. Dengue virus (DENV), chikungunya virus (CHIKV), and Zika virus (ZIKV) share the same vectors as well as similar clinical presentations, suggesting that combined surveillance would be useful. We hypothesized that blood spotted on dengue rapid diagnostic tests (RDTs) could be harnessed for sample collection in remote areas for subsequent detection of DENV, CHIKV, and ZIKV by reverse transcription real-time polymerase chain reaction (RT-qPCR). CHIKV and ZIKV dilutions were spotted on dengue RDTs (SD BIOLINE Dengue DUO, Standard Diagnostics, Gyeonggi-do, Republic of Korea), dried, and extracted. As reference, aliquots of each viral dilution were directly extracted. Using specific RT-qPCR tests, both viruses were successfully detected from RDT extracts. However, the limit of detection was slightly lower in comparison to direct extracts, two logfold for CHIKV and one logfold for ZIKV. For analysis of temperature stability, DENV dilutions were spotted on RDTs and stored for up to 2 months at −80°C, 4°C, or 35°C before testing. Storage of RDTs for 2 months at 35°C did not compromise detection of RNA by RT-qPCR; only minimal degradation was observed. This proof-of-principle study demonstrates the potential of using dengue RDTs for DENV/CHIKV/ZIKV combined surveillance in areas without access to laboratory facilities. Further investigations are needed for evaluation of tri-viral surveillance under field conditions using patient samples. Large-scale implementation of surveillance for these viruses is of crucial public health importance for the early detection of epidemics. This method also has important implications for improving understanding of the molecular epidemiology of the three viruses.

Chikungunya virus Detection in Aedes aegypti and Culex quinquefasciatus during an Outbreak in the Amazon Region

Chikungunya virus (CHIKV) was first reported in Brazil in 2014 and, after it spread countrywide, an outbreak of febrile illness with reports of arthralgia happened in the municipality of Xinguara, Pará, Brazil in 2017, indicating the virus' circulation. Here, we aimed to investigate CHIKV in mosquito vectors collected during an active surveillance of virus isolation in cell culture by using molecular detection and viral genome sequencing. A total of 492 Aedes, Culex and Mansonia mosquitoes were collected and separated in 36 pools according to the species and sex, and 22.2% (8/36) were positive. CHIKV was indentified in pools of Ae. aegypti females (n = 5), an Ae. aegypti male (n = 1) and in Culex quinquefasciatus females (n = 2). However, as the mosquitoes' whole bodies were macerated and used for detection, one cannot suggest the role of the latter in the viral transmission. Despite this, vector competence studies must be carried out in the different species to investigate long-term adaptations. Viral genome sequencing has characterized the East-Central-South-African (ECSA) genotype in all positive pools analyzed, corroborating previous reports for the Amazon region.

Epidemic Alphaviruses: Ecology, Emergence and Outbreaks

Over the past century, the emergence/reemergence of arthropod-borne zoonotic agents has been a growing public health concern. In particular, agents from the genus Alphavirus pose a significant risk to both animal and human health. Human alphaviral disease presents with either arthritogenic or encephalitic manifestations and is associated with significant morbidity and/or mortality. Unfortunately, there are presently no vaccines or antiviral measures approved for human use. The present review examines the ecology, epidemiology, disease, past outbreaks, and potential to cause contemporary outbreaks for several alphavirus pathogens.

A clinical scoring system to predict long-term arthralgia in Chikungunya disease: A cohort study

BACKGROUND

Chikungunya virus (CHIKV) has caused worldwide epidemics that impose a major burden on health systems. Approximately half of infected individuals develop chronic debilitating arthralgia, affecting their quality of life. Here, we identified the relevant clinical and demographic variables in the acute phase of CHIKV infection prospectively linked to chronic arthralgia to elaborate a prognostic scoring system.

METHODS

Acute CHIKV infection cases (n = 134) confirmed by serology or molecular test were examined <10 days of disease onset and followed for one year to evaluate for disease progression. Potential risk factors for chronic arthralgia were evaluated by multivariate analysis to develop a prognostic scoring system, which was subsequently tested in an independent validation cohort consisting of 42 individuals.

RESULTS

A total of 107 out of 134 (80%) acute CHIKV-confirmed cases from the derivation cohort were re-examined one year after enrollment. Chronic arthralgia post-CHIKV infection was diagnosed in 64 (60%). Five of the 12 parameters evaluated in the acute phase were statistically associated with persistent arthralgia and were further tested by Bayesian analysis. These variables were weighted to yield a prognosis score denominated SHERA (Sex, Hypertension, Edema, Retroocular pain, Age), which exhibited 81.3% accuracy in predicting long-term arthralgia post-CHIKV infection in the derivation cohort, and 76.5% accuracy in the validation cohort.

CONCLUSIONS

The simplified and externally validated prognostic scoring system, SHERA, is a useful method to screen acutely CHIKV-infected patients at elevated risk of chronic arthralgia who will benefit from specific interventions. This tool could guide public health policies, particularly in resource-constrained settings.

Chikungunya resurgence in the Maldives and risk for importation via tourists to Europe in 2019-2020: A GeoSentinel case series

Background

Chikungunya virus (CHIKV) is an arthropod-borne virus mainly transmitted in tropical areas by Aedes spp. mosquitoes. It has been responsible for small-to-large outbreaks in temperate areas including southern Europe and North America. Past outbreaks in 2006 on the islands of Maldives, as well as on other islands in the Indian Ocean and in Southeast Asia, demonstrated for the first time the capacity of CHIKV to disseminate through travel and transcontinental commerce, and revealed the major socio-economic impact of CHIKV epidemics. Recently, CHIKV has been circulating in highly touristic areas including the Maldives, where 1736 cases were notified by the Health Protection Agency during 2019.

Case series

Among EuroTravNet/GeoSentinel patient records, eight CHIKV-confirmed cases imported the Maldives to France, Germany, Denmark, Italy and Spain were identified between February 2019 and February 2020; exceeding the total number of CHIKV infections travel-acquired in Maldives reported to this surveillance network during the previous 10 years.

Conclusions

The prevention and control of CHIKV introduction into naïve areas colonised by competent vectors is crucial. CHIKV outbreaks must be detected and reported in a timely manner. This must lead to adapted health information for international travellers and to prompt management of suspected imported cases. Conversely, travellers make for excellent sentinels and increased reports of imported cases might reflect a change in the level of endemicity or even herald an outbreak. Feedback to the local health authorities and matching this with local epidemiological surveillance data may lead to health benefits for the local population.

Association of Genetic Polymorphisms in DC-SIGN, Toll-Like Receptor 3, and Tumor Necrosis Factor α Genes and the Lewis-Negative Phenotype With Chikungunya Infection and Disease in Nicaragua

Background

Chikungunya infections range from subclinical infection to debilitating arthralgia and to chronic inflammatory rheumatism. Tumor necrosis factor (TNF) α, DC-SIGN (dendritic cell–specific intercellular adhesion molecule 3–grabbing nonintegrin), Toll-like receptor (TLR) 3, and blood groups have been directly or indirectly implicated in the susceptibility and pathogenesis of chikungunya.

Methods

To test the hypothesis that polymorphisms in genes coding for these molecules determine clinical outcomes of chikungunya infection, a retrospective case-control study was performed in León, Nicaragua. The study included 132 case patients and 132 controls, matched for age, sex and neighborhood. Case patients had clinical symptoms of chikungunya, which was diagnosed by means of polymerase chain reaction. Controls were individuals not reporting abrupt presentation of clinical chikungunya-like symptoms. Polymorphisms were identified by TaqMan single-nucleotide polymorphism genotyping assays.

Results

After adjustment for sociodemographic risk factors, chikungunya disease was associated with polymorphism in DC-SIGN and TLR3 genes (odds ratios, 5.2 and 3.3, respectively), and TNF-α with reduced persistent joint pain (0.24). Persistent joint pain was also associated with age, female sex and other comorbid conditions. Most interestingly, the Lewis-negative phenotype was strongly associated with both symptomatic chikungunya and immunoglobulin G seropositivity (odds ratios, 2.7, and 3.3, respectively).

Conclusion

This study identified polymorphisms in DC-SIGN, TLR3, and TNF-α genes as well as Lewis-negative phenotype as risk factors for chikungunya infection and disease progression.

Bortezomib inhibits chikungunya virus replication by interfering with viral protein synthesis

Chikungunya virus (CHIKV) is an alphavirus that causes a febrile illness accompanied by myalgia and arthralgia. Despite having re-emerged as a significant public health threat, there are no approved therapeutics or prophylactics for CHIKV infection. In this study, we explored the anti-CHIKV effects of proteasome inhibitors and their potential mechanism of antiviral action. A panel of proteasome inhibitors with different functional groups reduced CHIKV infectious titers in a dose-dependent manner. Bortezomib, which has been FDA-approved for multiple myeloma and mantle cell lymphoma, was further investigated in downstream studies. The inhibitory activities of bortezomib were confirmed using different cellular models and CHIKV strains. Time-of-addition and time-of-removal studies suggested that bortezomib inhibited CHIKV at an early, post-entry stage of replication. In western blot analysis, bortezomib treatment resulted in a prominent decrease in structural protein levels as early as 6 hpi. Contrastingly, nsP4 levels showed strong elevations across all time-points. NsP2 and nsP3 levels showed a fluctuating trend, with some elevations between 12 to 20 hpi. Finally, qRT-PCR data revealed increased levels of both positive- and negative-sense CHIKV RNA at late stages of infection. It is likely that the reductions in structural protein levels is a major factor in the observed reductions in virus titer, with the alterations in non-structural protein ratios potentially being a contributing factor. Proteasome inhibitors like bortezomib likely disrupt CHIKV replication through a variety of complex mechanisms and may display a potential for use as therapeutics against CHIKV infection. They also represent valuable tools for studies of CHIKV molecular biology and virus-host interactions.

Comparison of Chikungunya Virus and Zika Virus Replication and Transmission Dynamics in Aedes aegypti Mosquitoes

Chikungunya virus (CHIKV) and Zika virus (ZIKV) are arthropod-borne viruses transmitted mainly by Aedes aegypti mosquitoes. These viruses have become endemic in large parts of North, Central, and South America. Arboviruses persistently infect mosquitoes throughout their life span and become infectious (i.e., expectorate infectious virus in saliva) after a period of time called the extrinsic incubation period (EIP). The duration of this infectiousness, however, is not well characterized. This is an important shortcoming because many epidemiological models assume that mosquitoes continue to be infectious for the duration of their life span. To define the duration of infectiousness for CHIKV and ZIKV, mosquitoes were infected orally with these viruses. Every 2 days, legs/wings, midguts, salivary glands, and saliva were collected from 30 to 60 mosquitoes and viral load measured. In CHIKV-infected mosquitoes, infectious virus in saliva peaked early (2–4 dpi), and then decreased rapidly and was rarely observed after 10 dpi. Viral RNA in infected tissues also decreased after the initial peak (4–8 dpi) but did so much less drastically. In ZIKV-infected mosquitoes, the infectious virus in saliva peaked at 12–14 dpi and dropped off only slightly after 14 dpi. In infected tissues, viral RNA increased early during infection, and then plateaued after 6–10 days. Our findings suggest that significant variation exists in the duration of the infectious period for arboviruses that is in part influenced by virus clearance from expectorated saliva.

Disease Resolution in Chikungunya-What Decides the Outcome?

Chikungunya disease (CHIKD) is a viral infection caused by an alphavirus, chikungunya virus (CHIKV), and triggers large outbreaks leading to epidemics. Despite the low mortality rate, it is a major public health concern owing to high morbidity in affected individuals. The complete spectrum of this disease can be divided into four phases based on its clinical presentation and immunopathology. When a susceptible individual is bitten by an infected mosquito, the bite triggers inflammatory responses attracting neutrophils and initiating a cascade of events, resulting in the entry of the virus into permissive cells. This phase is termed the pre-acute or the intrinsic incubation phase. The virus utilizes the cellular components of the innate immune system to enter into circulation and reach primary sites of infection such as the lymph nodes, spleen, and liver. Also, at this point, antigen-presenting cells (APCs) present the viral antigens to the T cells thereby activating and initiating adaptive immune responses. This phase is marked by the exhibition of clinical symptoms such as fever, rashes, arthralgia, and myalgia and is termed the acute phase of the disease. Viremia reaches its peak during this phase, thereby enhancing the antigen-specific host immune response. Simultaneously, T cell-mediated activation of B cells leads to the formation of CHIKV specific antibodies. Increase in titres of neutralizing IgG/IgM antibodies results in the clearance of virus from the bloodstream and marks the initiation of the post-acute phase. Immune responses mounted during this phase of the infection determine the degree of disease progression or its resolution. Some patients may progress to a chronic arthritic phase of the disease that may last from a few months to several years, owing to a compromised disease resolution. The present review discusses the immunopathology of CHIKD and the factors that dictate disease progression and its resolution.

Current Efforts in the Development of Vaccines for the Prevention of Zika and Chikungunya Virus Infections

Arboviruses represent major challenges to public health, particularly in tropical, and subtropical regions, and a substantial risk to other parts of the world as respective vectors extend their habitats. In recent years, two viruses transmitted by Aedes mosquitoes, Chikungunya and Zika virus, have gathered increased interest. After decades of regionally constrained outbreaks, both viruses have recently caused explosive outbreaks on an unprecedented scale, causing immense suffering and massive economic burdens in affected regions. Chikungunya virus causes an acute febrile illness that often transitions into a chronic manifestation characterized by debilitating arthralgia and/or arthritis in a substantial subset of infected individuals. Zika infection frequently presents as a mild influenza-like illness, often subclinical, but can cause severe complications such as congenital malformations in pregnancy and neurological disorders, including Guillain-Barré syndrome. With no specific treatments or vaccines available, vector control remains the most effective measure to manage spread of these diseases. Given that both viruses cause antibody responses that confer long-term, possibly lifelong protection and that such responses are cross-protective against the various circulating genetic lineages, the development of Zika and Chikungunya vaccines represents a promising route for disease control. In this review we provide a brief overview on Zika and Chikungunya viruses, the etiology and epidemiology of the illnesses they cause and the host immune response against them, before summarizing past and current efforts to develop vaccines to alleviate the burden caused by these emerging diseases. The development of the urgently needed vaccines is hampered by several factors including the unpredictable epidemiology, feasibility of rapid clinical trial implementation during outbreaks and regulatory pathways. We will give an overview of the current developments.

In-depth characterization of a novel live-attenuated Mayaro virus vaccine candidate using an immunocompetent mouse model of Mayaro disease

Mayaro virus (MAYV) is endemic in South American countries where it is responsible for sporadic outbreaks of acute febrile illness. The hallmark of MAYV infection is a highly debilitating and chronic arthralgia. Although MAYV emergence is a potential threat, there are no specific therapies or licensed vaccine. In this study, we developed a murine model of MAYV infection that emulates many of the most relevant clinical features of the infection in humans and tested a live-attenuated MAYV vaccine candidate (MAYV/IRES). Intraplantar inoculation of a WT strain of MAYV into immunocompetent mice induced persistent hypernociception, transient viral replication in target organs, systemic production of inflammatory cytokines, chemokines and specific humoral IgM and IgG responses. Inoculation of MAYV/IRES in BALB/c mice induced strong specific cellular and humoral responses. Moreover, MAYV/IRES vaccination of immunocompetent and interferon receptor-defective mice resulted in protection from disease induced by the virulent wt MAYV strain. Thus, this study describes a novel model of MAYV infection in immunocompetent mice and highlights the potential role of a live-attenuated MAYV vaccine candidate in host's protection from disease induced by a virulent MAYV strain.

Chikungunya: Epidemiology, Pathogenesis, Clinical Features, Management, and Prevention

Chikungunya, a zoonotic disease caused by the Chikungunya virus (CHIKV), is transmitted by infected Aedes spp mosquitoes. CHIKV has now spread to more than 100 countries and is listed on the WHO Blueprint priority pathogens. After an incubation period of 1 to 12 days, symptoms similar to other febrile infections appear, with a sudden onset of high fever, nausea, polyarthralgia, myalgia, widespread skin rash, and conjunctivitis. Serious complications include myocarditis, uveitis, retinitis, hepatitis, acute renal disease, severe bullous lesions, meningoencephalitis, Guillain-Barré syndrome, myelitis, and cranial nerve palsies. Treatment is supportive; there is no specific antiviral treatment and no effective vaccine.

A Factor I-Like Activity Associated with Chikungunya Virus Contributes to Its Resistance to the Human Complement System

Chikungunya virus (CHIKV) is an emerging pathogen capable of causing explosive outbreaks. Prior studies showed that exacerbation in arthritogenic alphavirus-induced pathogenesis is attributed to its interaction with multiple immune components, including the complement system. Viremia concomitant to CHIKV infection makes exposure of the virus to complement unavoidable, yet very little is known about CHIKV-complement interactions. Here, we show that CHIKV activated serum complement to modest levels in a concentration- and time-dependent manner, but the virus effectively resisted complement-mediated neutralization. Heat-inactivated serum from seropositive donors could actively neutralize CHIKV due to the presence of potent anti-CHIKV antibodies. Deposition of key complement components C3 and C4 did not alter the resistance of CHIKV to complement. Further, we identified a factor I-like activity in CHIKV that limited complement by inactivating C3b into inactive C3b (iC3b), the complement component known to significantly contribute to disease severity in vivo, but this activity had no effect on C4b. Inactivation of C3b by CHIKV was largely dependent on the concentration of the soluble host cofactor factor H and the virus concentration. A factor I function-blocking antibody had only a negligible effect on the factor I-like activity associated with CHIKV, suggesting that this activity is independent of host factor I and could be of viral origin. Thus, our findings suggest a complement modulatory action of CHIKV which not only helps the virus to evade human complement but may also have implications in alphavirus-induced arthritogenic symptoms.IMPORTANCE Chikungunya virus is a vector-borne pathogen of global significance. The morbidity associated with chikungunya virus (CHIKV) infection, neurovirulence and adaptability to Aedes albopictus, necessitates a deeper understanding of the interaction of CHIKV with the host immune system. Here, we demonstrate that CHIKV is resistant to neutralization by one of the potent barriers of the innate immune arm, the complement system. Chikungunya virus showed marked resistance to complement despite activation and deposition of complement proteins. Interestingly the C3 component associated with the virion was found to be inactive C3b (iC3b), a key factor implicated in the pathogenesis and disease severity in the mouse model of Ross River virus infection. CHIKV also had an associated unique factor I-like activity that mediated the inactivation of C3b into iC3b. We have unraveled a smart strategy adopted by CHIKV to limit complement which has serious implications in viral dissemination, pathogenesis, and disease.

Chikungunya outbreak in Bangladesh (2017): Clinical and hematological findings

Introduction

A massive outbreak of chikungunya virus (CHIKV) occurred in Bangladesh during the period of April-September 2017, and over two million people were at risk of getting infected by the virus. A prospective cohort of viremic patients was constituted and analyzed to define the clinical, hematological, and long-term aspects of this outbreak.

Methods

A 35-day long comprehensive survey was conducted in two major, neighboring cities, Dhaka and Mymensingh. One-hundred and eighty-seven laboratory-confirmed CHIKV cases were enrolled in the cross-sectional cohort study. Additionally, a smaller group of 48 chikungunya patients was monitored for post-infection effects for 12 months.

Results

Clinical data revealed that a combination of fever and arthralgia (oligoarthralgia and/or polyarthralgia) was the cardinal hallmark (97.9% of cases) of the infection. Hematological analysis showed that irrespective of age and sex groups, CHIKV patients had a decreased level of hemoglobin (n = 64, p < 0.01) and elevated erythrocyte sedimentation rate (n = 131, p < 0.01). Besides, a significant portion of the patients represented abnormal values for RBC (n = 38, p = 0.0005) and WBC (n = 63, p < 0.01) counts. The post-infection study revealed that children had an early recovery from the infection compared to the adults. Moreover, post-infection weakness, successive relapse of arthralgic pain, and memory problems were the most significant aftereffects, which had an impact on the daily activities of patients.

Conclusions

This study represents a comprehensive overview of clinical and epidemiological features of the 2017 outbreak of CHIKV in Bangladesh as well as its chronic outcomes till the 12^th month. It provides insights into the natural history of this disease, which may help to improve the management of CHIKV patients.

The clinical profile, epidemiology, and the economic impacts during the acute phase of chikungunya infection have been studied quite rigorously. However, studies regarding the hematological features and chronic consequences are infrequent. In this study, we analyzed the clinical and hematological features of 187 chikungunya patients in the acute phase of the infection. Also, we monitored a smaller group of 48 patients until 12 months to study its post-infection consequences. Clinical data revealed that a combination of fever and joint pain (arthralgia) was the cardinal hallmark in the acute phase of the infection. Hematological analysis showed that CHIKV infection features a significantly reduced hemoglobin and remarkably elevated erythrocyte sedimentation rate. Besides, RBC and WBC counts, especially in children and females, were beyond the reference values. The post-infection consequence study unveiled that children recovered better from the infection compared to the adults. Further, post-infection weakness, successive relapse of joint pain and memory problems were the most significant aftereffects. Overall, the infection had a moderate to severe impact on the daily activities of the respondents. This study provides insights into the clinical and hematological aspects of chikungunya infection during the acute phase as well as describes an account for its chronic outcomes, which puts forward to the knowledge for clinicians and epidemiologists regarding the infection diversity and to help improve patient management.

Immunogenicity, safety, and tolerability of the measles-vectored chikungunya virus vaccine MV-CHIK: a double-blind, randomised, placebo-controlled and active-controlled phase 2 trial

BACKGROUND

Chikungunya fever is an emerging viral disease and substantial threat to public health. We aimed to assess the safety, tolerability, and immunogenicity of a live-attenuated, measles-vectored chikungunya vaccine (MV-CHIK).

METHODS

In this double-blind, randomised, placebo-controlled and active-controlled phase 2 trial, we enrolled healthy volunteers aged 18-55 years at four study sites in Austria and Germany. Participants were randomly assigned to receive intramuscular injections with MV-CHIK (5 × 10⁴ or 5 × 10⁵ 50% tissue culture infectious dose), control vaccine, or measles prime and MV-CHIK, in two different administration regimens. Randomisation was done by use of three-digit randomisation codes in envelopes provided by a data management service. The participants and investigators were masked to treatment assignment, which was maintained by use of sterile saline as a placebo injection. The primary endpoint was immunogenicity, defined as the presence of neutralising antibodies against chikungunya virus, at day 56, which is 28 days after one or two immunisations. The primary endpoint was assessed in all participants who completed the study without major protocol deviations (per-protocol population) and in all randomised participants who received at least one study treatment (modified intention-to-treat population). The safety analysis included all participants who received at least one study treatment. This trial is registered with ClinicalTrials.gov (NCT02861586) and EudraCT (2015-004037-26) and is completed.

FINDINGS

Between Aug 17, 2016, and May 31, 2017, we randomly assigned 263 participants to receive control vaccine (n=34), MV-CHIK (n=195), or measles prime and MV-CHIK (n=34). 247 participants were included in the per-protocol population. Neutralising antibodies against chikungunya virus were detected in all MV-CHIK treatment groups after one or two immunisations, with geometric mean titres ranging from 12·87 (95% CI 8·75-18·93) to 174·80 (119·10-256·50) and seroconversion rates ranging from 50·0% to 95·9% depending on the dose and administration schedule. Adverse events were similar between groups, with solicited adverse events reported in 168 (73%) of 229 participants assigned to MV-CHIK and 24 (71%) of 34 assigned to control vaccine (p=0·84) and unsolicited adverse events in 116 (51%) participants assigned to MV-CHIK and 17 (50%) assigned to control vaccine (p=1·00). No serious adverse events related to the vaccine were reported.

INTERPRETATION

MV-CHIK showed excellent safety and tolerability and good immunogenicity, independent of pre-existing immunity against the vector. MV-CHIK is a promising candidate vaccine for the prevention of chikungunya fever, an emerging disease of global concern.

FUNDING

Themis.

A customized program for the identification of conserved protein sequence motifs

We searched for viral protein sequences that could be important for tissue tropism. To achieve this goal, human pathogenic viruses were classified according to the tissue they infect (e.g., pulmonary), irrespective of whether they were enveloped or non-enveloped RNA or DNA viruses. Next, we developed an amino acid sequence alignment program and identified the conserved amino acid motif, VAIVLGG, in alphaviruses. The VAIVLGG sequence is located on the structural capsid protein of the chikungunya virus, a mosquito-borne arthrogenic member of the alphaviruses. Capsid protein translocation onto the host cell membrane is a required step for virion budding. Our identified VAIVLGG consensus sequence might potentially be used for developing a pan-vaccine effective against alphaviruses.

Structural and phenotypic analysis of Chikungunya virus RNA replication elements

Chikungunya virus (CHIKV) is a re-emerging, pathogenic Alphavirus transmitted to humans by Aedes spp. mosquitoes. We have mapped the RNA structure of the 5′ region of the CHIKV genome using selective 2′-hydroxyl acylation analysed by primer extension (SHAPE) to investigate intramolecular base-pairing at single-nucleotide resolution. Taking a structure-led reverse genetic approach, in both infectious virus and sub-genomic replicon systems, we identified six RNA replication elements essential to efficient CHIKV genome replication - including novel elements, either not previously analysed in other alphaviruses or specific to CHIKV. Importantly, through a reverse genetic approach we demonstrate that the replication elements function within the positive-strand genomic copy of the virus genome, in predominantly structure-dependent mechanisms during efficient replication of the CHIKV genome. Comparative analysis in human and mosquito-derived cell lines reveal that a novel element within the 5′UTR is essential for efficient replication in both host systems, while those in the adjacent nsP1 encoding region are specific to either vertebrate or invertebrate host cells. In addition to furthering our knowledge of fundamental aspects of the molecular virology of this important human pathogen, we foresee that results from this study will be important for rational design of a genetically stable attenuated vaccine.

Natural Infection of Aedes aegypti by Chikungunya and Dengue type 2 Virus in a Transition Area of North-Northeast Brazil

Dengue fever, chikungunya, and Zika are diseases caused by viruses transmitted by Aedes aegypti and Aedes albopictus. In Brazil, the number of human infections is high, but few studies are performed in mosquito vectors. This study aimed to investigate the presence of Zika, Dengue and Chikungunya viruses in Ae. aegypti and Ae. albopictus from the municipalities of Alto Alegre, Caxias, Codó, and São Mateus do Maranhão, located in the state of Maranhão, Northeast Brazil. The mosquitoes were collected with a mechanical aspirator, identified, triturated, and then submitted to RNA extraction and RT-qPCR. The positive samples were confirmed by virus isolation and genome sequencing. Three hundred and forty-eight Ae. aegypti (176 males and 172 females) and 12 Ae. albopictus (eight males and four females) were collected and tested. Ae. aegypti was the only vector positive in two municipalities-Codó, with detection of Chikungunya virus (CHIKV) belonging to the East-Central-South African genotype, and in Caxias, with detection of Dengue virus (DENV)-2 belonging to the Asian/American genotype. The detection of CHIKV and DENV-2 is evidence that those viruses are maintained in arthropod vectors, and shows the epidemiological risk in the area for chikungunya cases and a possible increase of severe dengue cases, associated with the occurrence of dengue hemorrhagic fever.

Pathogenic Th1 responses in CHIKV-induced inflammation and their modulation upon Plasmodium parasites co-infection

The induction of polyarthritis and polyarthralgia is a hallmark of arthritogenic alphavirus infections, with an exceptionally higher morbidity observed with chikungunya virus (CHIKV). While the mechanisms underlying these incapacitating acute symptoms remain partially understood, the progression to chronic conditions in some cases remains unanswered. The highly pro‐inflammatory nature of alphavirus disease has suggested the involvement of virus‐specific, joint‐infiltrating Th1 cells as one of the main pathogenic mediators of CHIKV‐induced joint pathologies. This review summarizes the role of cell‐mediated immune responses in CHIKV pathogenesis, with a specific focus on pro‐inflammatory Th1 responses in the development of CHIKV joint inflammation. Furthermore, due to the explosive nature of arthritogenic alphavirus outbreaks and their recent expansion across the world, co‐infections with other highly prevalent pathogens such as malaria are likely to occur but the pathological outcomes of such interactions in humans are unknown. This review will also discuss the potential impact of malaria co‐infections on CHIKV pathogenesis and their relevance in alphavirus control programs in endemic areas.

A patent perspective on chikungunya

Chikungunya is a viral disease caused by chikungunya virus (CHIKV) belonging to the Alphavirus genus and transmitted to humans by mosquitoes of Aedes spp. Nearly 40 countries in Asia, Africa, Europe, and the Americas have documented chikungunya cases. Most recent severe outbreaks have occurred in Indian Ocean islands of Réunion and Mauritius and India. There is no specific drug treatment for the disease, neither is there a standardized vaccine available for prevention of the disease. The present review gives a global perspective on patents filed pertaining to chikungunya. The United States has been the top patent filing jurisdiction followed by China, Europe, and India. The patents have been classified into categories of therapeutics, diagnostics, and vaccines. Maximum patent documents fall under the therapeutics category, in which patent applications are predominantly related to chemically derived drugs. They include nucleic acid analogues, various other host and virus enzyme/protein inhibitors. Patents on biological or plant derived drugs are being filed relatively recently. In the category of diagnostics, immunoassay based tests seemed to be of choice until the year 2005, whereas, patent filings for molecular diagnostics have now surpassed those with immunoassay techniques. In the vaccines category, vaccines based on viral vectors appear to be emerging as the preferred vaccine platform with the majority of patents filed in the years 2014-2017. Corporate sector has the most patent filings to its credit, followed closely by academic institutions. Pasteur Institut along with Chinese Agency for Science, Technology and Research is the top patent filing entity in chikungunya related technology space. Presently, nine vaccine products, three antiviral drugs and one mRNA based gene therapy are under development. Three vaccine products have been given fast track designation by US Food and Drug Administration (FDA) to expedite review and facilitate the development of a vaccine to prevent a serious or life-threatening condition and fill an unmet medical need. Similarly, one vaccine has been given PRIME (Priority Medicines) status by the European Medicines Agency (EMA).

Chikungunya virus requires cellular chloride channels for efficient genome replication

Chikungunya virus (CHIKV) is a re-emerging, pathogenic alphavirus that is transmitted to humans by Aedes spp. mosquitoes-causing fever and debilitating joint pain, with frequent long-term health implications and high morbidity. The CHIKV lifecycle is poorly understood and specific antiviral therapeutics or vaccines are lacking. In this study, we investigated the role of host-cell chloride (Cl-) channels on CHIKV replication.We demonstrate that specific pharmacological Cl- channel inhibitors significantly inhibit CHIKV replication in a dose-dependent manner, suggesting that Cl-channels are pro-viral factors in human cells. Further analysis of the effect of the inhibitors on CHIKV attachment, entry, viral protein expression and replicon replication demonstrated that Cl- channels are specifically required for efficient CHIKV genome replication. This was conserved in mosquito cells, where CHIKV replication and genome copy number was significantly reduced following Cl- channel inhibition. siRNA silencing identified chloride intracellular channels 1 and 4 (CLIC1 and CLIC4, respectively) as required for efficient CHIKV replication and protein affinity chromatography showed low levels of CLIC1 in complex with CHIKV nsP3, an essential component of the viral replication machinery. In summary, for the first time we demonstrate that efficient replication of the CHIKV genome depends on cellular Cl- channels, in both human and mosquito cells and identifies CLIC1 and CLIC4 as agonists of CHIKV replication in human cells. We observe a modest interaction, either direct or indirect, between CLIC1 and nsP3 and hypothesize that CLIC1 may play a role in the formation/maintenance of CHIKV replication complexes. These findings advance our molecular understanding of CHIKV replication and identify potential druggable targets for the treatment and prevention of CHIKV mediated disease.

Updated Phylogeny of Chikungunya Virus Suggests Lineage-Specific RNA Architecture

Chikungunya virus (CHIKV), a mosquito-borne alphavirus of the family Togaviridae, has recently emerged in the Americas from lineages from two continents: Asia and Africa. Historically, CHIKV circulated as at least four lineages worldwide with both enzootic and epidemic transmission cycles. To understand the recent patterns of emergence and the current status of the CHIKV spread, updated analyses of the viral genetic data and metadata are needed. Here, we performed phylogenetic and comparative genomics screens of CHIKV genomes, taking advantage of the public availability of many recently sequenced isolates. Based on these new data and analyses, we derive a revised phylogeny from nucleotide sequences in coding regions. Using this phylogeny, we uncover the presence of several distinct lineages in Africa that were previously considered a single one. In parallel, we performed thermodynamic modeling of CHIKV untranslated regions (UTRs), which revealed evolutionarily conserved structured and unstructured RNA elements in the 3'UTR. We provide evidence for duplication events in recently emerged American isolates of the Asian CHIKV lineage and propose the existence of a flexible 3'UTR architecture among different CHIKV lineages.

Chikungunya Virus Vaccine Candidates with Decreased Mutational Robustness Are Attenuated In Vivo and Have Compromised Transmissibility

Chikungunya virus (CHIKV) is a reemerged arbovirus, a member of the Togaviridae family. It circulates through mosquito vectors mainly of the Aedes family and a mammalian host. CHIKV causes chikungunya fever, a mild to severe disease characterized by arthralgia, with some fatal outcomes described. In the past years, several outbreaks mainly caused by enhanced adaptation of the virus to the vector and ineffective control of the contacts between infected mosquito populations and the human host have been reported. Vaccines represent the best solution for the control of insect-borne viruses, including CHIKV, but are often unavailable. We designed live attenuated CHIKVs by applying a rational genomic design based on multiple replacements of synonymous codons. In doing so, the virus mutational robustness (capacity to maintain phenotype despite introduction of mutations to genotype) is decreased, driving the viral population toward deleterious evolutionary trajectories. When the candidate viruses were tested in the insect and mammalian hosts, we observed overall strong attenuation in both and greatly diminished signs of disease. Moreover, we found that the vaccine candidates elicited protective immunity related to the production of neutralizing antibodies after a single dose. During an experimental transmission cycle between mosquitoes and naive mice, vaccine candidates could be transmitted by mosquito bite, leading to asymptomatic infection in mice with compromised dissemination. Using deep-sequencing technology, we observed an increase in detrimental (stop) codons, which confirmed the effectiveness of this genomic design. Because the approach involves hundreds of synonymous modifications to the genome, the reversion risk is significantly reduced, rendering the viruses promising vaccine candidates.IMPORTANCE Chikungunya fever is a debilitating disease that causes severe pain to the joints, which can compromise the patient's lifestyle for several months and even in some grave cases lead to death. The etiological agent is chikungunya virus, an alphavirus transmitted by mosquito bite. Currently, there are no approved vaccines or treatments against the disease. In our research, we developed novel live attenuated vaccine candidates against chikungunya virus by applying an innovative genomic design. When tested in the insect and mammalian host, the vaccine candidates did not cause disease, elicited strong protection against further infection, and had low risk of reversion to pathogenic phenotypes.

Arboviruses in the East African Community partner states: a review of medically important mosquito-borne Arboviruses

Mosquito-borne diseases, including arbovirus-related diseases, make up a large proportion of infectious disease cases worldwide, causing a serious global public health burden with over 700,000 deaths annually. Mosquito-borne arbovirus outbreaks can range from global to regional. In the East African Community (EAC) region, these viruses have caused a series of emerging and reemerging infectious disease outbreaks. Member states in the EAC share a lot in common including regional trade and transport, some of the factors highlighted to be the cause of mosquito-borne arbovirus disease outbreaks worldwide. In this review, characteristics of 24 mosquito-borne arboviruses indigenous to the EAC are reviewed, including lesser or poorly understood viruses, like Batai virus (BATV) and Ndumu virus (NDUV), which may escape their origins under perfect conditions to establish a foothold in new geographical locations. Factors that may influence the future spread of these viruses within the EAC are addressed. With the continued development observed in the EAC, strategies should be developed by the Community in improving mosquito and mosquito-borne arbovirus surveillance to prevent future outbreaks.

Current status of dengue virus, poliovirus, and chikungunya virus in Pakistan

Epidemics of infectious diseases especially dengue virus (DENV), chikungunya virus (CHIKV), and poliovirus are the leading cause of mortality and morbidity in Pakistan. Risks associated with these outbreaks have drastic effects on the healthcare infrastructure and economy of the country. This report provides the current status of DENV, poliovirus, and CHIKV in Pakistan and further highlights the measures needed to control these infections.

Interferon-inducible protein (IFI) 16 regulates Chikungunya and Zika virus infection in human skin fibroblasts

Chikungunya virus (CHIKV), a re-emerging infectious arbovirus, causes Chikungunya fever that is characterized by fever, skin rash, joint pain, arthralgia and occasionally death. Despite it has been described for 66 years already, neither potential vaccine nor a specific drug is available yet. During CHIKV infection, interferon type I signaling pathway is stimulated and releases hundreds of interferon stimulated genes (ISGs). Our previous study reported that IFI16, a member of ISGs, is up-regulated during CHIKV virus infection and the suppression of the gene resulted in increased virus replication. Furthermore, our group also found that inflammasome activation can inhibit CHIKV infection in human foreskin cells (HFF1). Concomitantly, it has been reported that IFI16 activates the inflammasome to suppress virus infection. Therefore, we have hypothesized that IFI16 could be involved in CHIKV infection. In this study, we confirmed the expression level of IFI16 by Western blotting analysis and found that IFI16 was up-regulated following CHIKV infection in both HFF1 and human embryonic kidney cells. We next investigated its antiviral activity and found that forced expression of IFI16 completely restricted CHIKV infection while endogenous silencing of the gene markedly increased virus replication. Furthermore, we have discovered that IFI16 inhibited CHIKV replication, at least, in cell-to-cell transmission as well as the diffusion step. Interestingly, IFI16 also exerted its antiviral activity against Zika virus (ZIKV) infection, the global threat re-emerging virus can cause microcephaly in humans. Taken together, this study provides the first evidence of an antivirus activity of IFI16 during in vitro arbovirus infection, thus expanding its antiviral spectrum that paves the way to further development of antiviral drugs and vaccines.

Assessing the Potential Interactions between Cellular miRNA and Arboviral Genomic RNA in the Yellow Fever Mosquito, Aedes aegypti

Although the role of exogenous small interfering RNA (siRNA) and P-element induced wimpy testis (PIWI)-interacting RNA (piRNA) pathways in mosquito antiviral immunity is increasingly better understood, there is still little knowledge regarding the role of mosquito cellular microRNA (miRNA). Identifying direct interactions between the mosquito miRNAs and the RNA genome of arboviruses and choosing the relevant miRNA candidates to explore resulting antiviral mechanisms are critical. Here, we carried out genomic analyses to identify Aedes aegypti miRNAs that potentially interact with various lineages and genotypes of chikungunya, dengue, and Zika viruses. By using prediction tools with distinct algorithms, several miRNA binding sites were commonly found within different genotypes/and or lineages of each arbovirus. We further analyzed those miRNAs that could target more than one arbovirus, required a low energy threshold to form miRNA-viralRNA (vRNA) complexes, and predicted potential RNA structures using RNAhybrid software. We predicted miRNA candidates that might participate in regulating arboviral replication in Ae. aegypti. Even without any experimental validation, which should be done as a next step, this study can shed further light on the role of miRNA in mosquito innate immunity and targets for future studies.

Field diagnosis and genotyping of chikungunya virus using a dried reverse transcription loop-mediated isothermal amplification (LAMP) assay and MinION sequencing

Detection and sequencing of chikungunya virus (CHIKV) genome was performed using a combination of a modified reverse transcription loop-mediated isothermal amplification (RT-LAMP) method and a MinION sequencer. We developed the protocol for drying all the reagents for the RT-LAMP in a single reaction tube. Using this system, the CHIKV genome was effectively amplified under isothermal conditions, and used as a template for MinION sequencing with a laptop computer. Our in-house RT-LAMP method and MinION sequencing system were also validated with RNAs and serum samples from recent outbreaks of CHIKV patients in Brazil. The obtained sequence data confirmed the CHIKV outbreaks and identified the genotype. In summary, our established inexpensive on-site genome detection and sequencing system is applicable for both diagnosis of CHIKV infected patients and genotyping of the CHIKV virus in future outbreak in remote areas.

Chikungunya virus has re-emerged as an important pathogen causing several outbreaks in the world. As the clinical symptoms of chikungunya is similar to other mosquito-borne febrile diseases, the definitive diagnosis of the disease is based on the detection of viral genome from the patient blood. Loop-mediated isothermal amplification (LAMP) is a method that rapidly amplify nucleic acids under isothermal condition. In the present work, a simple dried format LAMP test for chikungunya diagnosis was developed which can be directly amplified from human blood. Combining with the portable sequencer MinION sequencing system, a method to identify the viral genotype was also established. The developed on-site diagnosis and genotyping system is easy to perform, sensitive, and rapid. Therefore, it offers great promise as a routine simple tool for diagnosis and disease management of chikungunya.

A detailed review of the mosquitoes (Diptera: Culicidae) of Iran and their medical and veterinary importance

Mosquitoes (Diptera: Culicidae) are the most significant arthropods of medical importance because of the burden of diseases, such as malaria, encephalitis and filariasis, which are caused by pathogens and parasites they transmit to humans. In 2007, the most recently published checklist of Iranian mosquitoes included 64 species representing seven genera. Public databases were searched to the end of August 2018 for publications concerning the diseases in Iran caused by mosquito-borne pathogens. Pertinent information was extracted and analyzed, and the checklist of Iranian mosquitoes was updated. Six arboviral diseases, two bacterial diseases, four helminthic diseases and two protozoal diseases occur in Iran. The agents of these diseases are biologically or mechanically known or assumed to be transmitted by mosquitoes. The updated checklist of Iranian mosquitoes includes 69 species representing seven or 11 genera depending on the generic classification of aedines. There is no published information about the role of mosquitoes in the transmission of the causal agents of avian malaria, avian pox, bovine ephemeral fever, dengue fever, Rift Valley fever, Sindbis fever, Deraiophoronema evansi infection, lymphatic filariasis, anthrax and tularemia in Iran. There is just one imported case of lymphatic filariasis, which is not endemic in the country. It seems arthropods do not play an important role in the epidemiology of anthrax and ixodid ticks are the main vectors of the tularemia bacterium. In view of the recent finding of only a few adults and larvae of Aedes albopictus in southeastern Iran and the absence of Ae. aegypti, it is not possible to infer the indigenous transmission of the dengue fever virus in Iran. Considering the importance of mosquito-borne diseases in the country, it is necessary to improve vector and vector-borne disease surveillance in order to apply the best integrated vector management interventions as a part of the One Health concept.

Rapid Diagnostic Platform for Colorimetric Differential Detection of Dengue and Chikungunya Viral Infections

In this work, we demonstrate a rapid diagnostic platform with potential to transform clinical diagnosis of acute febrile illnesses in resource-limited settings. Acute febrile illnesses such as dengue and chikungunya, which pose high burdens of disease in tropical regions, share many nonspecific symptoms and are difficult to diagnose based on clinical history alone in the absence of accessible laboratory diagnostics. Through a unique color-mixing encoding and readout strategy, our platform enabled consistent and accurate multiplexed detection of dengue and chikungunya IgM/IgG antibodies in human clinical samples within 30 min. Our multiplex assay offers several advantages over conventional rapid diagnostic tests deployed in resource-limited settings, including a low sample volume requirement and the ability to concurrently detect four analytes. Our platform is a step toward multiplexed diagnostics that will be transformative for disease management in resource-limited settings by enabling informed treatment decisions through accessible evidence-based diagnosis.

P38 and JNK Mitogen-Activated Protein Kinases Interact With Chikungunya Virus Non-structural Protein-2 and Regulate TNF Induction During Viral Infection in Macrophages

Chikungunya virus (CHIKV), a mosquito-borne Alphavirus, is endemic in different parts of the globe. The host macrophages are identified as the major cellular reservoirs of CHIKV during infection and this virus triggers robust TNF production in the host macrophages, which might be a key mediator of virus induced inflammation. However, the molecular mechanism underneath TNF induction is not understood yet. Accordingly, the Raw264.7 cells, a mouse macrophage cell line, were infected with CHIKV to address the above-mentioned question. It was observed that CHIKV induces both p38 and JNK phosphorylation in macrophages in a time-dependent manner and p-p38 inhibitor, SB203580 is effective in reducing infection even at lower concentration as compared to the p-JNK inhibitor, SP600125. However, inhibition of p-p38 and p-JNK decreased CHIKV induced TNF production in the host macrophages. Moreover, CHIKV induced macrophage derived TNF was found to facilitate TCR driven T cell activation. Additionally, it was noticed that the expressions of key transcription factors involved mainly in antiviral responses (p-IRF3) and TNF production (p-c-jun) were induced significantly in the CHIKV infected macrophages as compared to the corresponding mock cells. Further, it was demonstrated that CHIKV mediated TNF production in the macrophages is dependent on p38 and JNK MAPK pathways linking p-c-jun transcription factor. Interestingly, it was found that CHIKV nsP2 interacts with both p-p38 and p-JNK MAPKs in the macrophages. This observation was supported by the in silico protein-protein docking analysis which illustrates the specific amino acids responsible for the nsP2-MAPKs interactions. A strong polar interaction was predicted between Thr-180 (within the phosphorylation lip) of p38 and Gln-273 of nsP2, whereas, no such polar interaction was predicted for the phosphorylation lip of JNK which indicates the differential roles of p-p38 and p-JNK during CHIKV infection in the host macrophages. In summary, for the first time it has been shown that CHIKV triggers robust TNF production in the host macrophages via both p-p38 and p-JNK/p-c-jun pathways and the interaction of viral protein, nsP2 with these MAPKs during infection. Hence, this information might shed light in rationale-based drug designing strategies toward a possible control measure of CHIKV infection in future.

Chikungunya in Infants and Children: Is Pathogenesis Increasing?

Chikungunya virus (CHIKV) was first extensively described in children during outbreaks in India and South Asia during the mid-1960s. Prior to the 2005 emergence of CHIKV on Reunion Island, CHIKV infection was usually described as a dengue-like illness with arthralgia in Africa and febrile hemorrhagic disease in Asia. Soon after the 2005 emergence, severe CNS consequences from vertical and perinatal transmission were described and as CHIKV continued to emerge in new areas over the next 10 years, severe manifestation of infection and sequelae were increasingly reported in infants and neonates. The following review describes the global reemergence and the syndromes of Chikungunya fever (CHIKF) in infants and children. The various manifestations of CHIKF are described and connected to the viral lineage that was documented in the area at the time the disease was described. The data show that certain manifestations of CHIKF occur with specific viral lineages and genetic motifs, which suggests that severe manifestations of CHIKF in the very young may be associated with the emergence of new viral lineages.

The Clinical Features, Pathogenesis and Methotrexate Therapy of Chronic Chikungunya Arthritis

Chikungunya fever (CHIKF) is an emerging viral infection that has spread widely, along with its Aedes vectors, throughout the tropics and beyond, causing explosive epidemics of acute illness and persistent disabling arthritis. The rheumatic symptoms associated with chikungunya virus (CHIKV) infection include polyarthralgia, polyarthritis, morning stiffness, joint edema, and erythema. Chronic CHIK arthritis (CCA) often causes severe pain and associated disability. The pathogenesis of CCA is not well understood. Proposed hypotheses include the persistence of a low level of replicating virus in the joints, the persistence of viral RNA in the synovium, and the induction of autoimmunity. In this review, we describe the main hypotheses of CCA pathogenesis, some of which support methotrexate (MTX) treatment which has been shown to be effective in preliminary studies in CCA.

Retrospective investigation of antibodies against chikungunya virus (CHIKV) in serum from febrile patients in Mozambique, 2009-2015: Implications for its prevention and control

Introduction

Longitudinal data and trends about chikungunya virus (CHIKV) are critical for its control, however in Mozambique very few studies were conducted over 5 decades, between 1957 and 2013. In this study, we retrospectively investigated the occurrence, geographical distribution and trend of anti-CHIKV antibodies between 2009 and 2015 in Mozambique using serum samples from febrile patients.

Methods

A total of 895 serum samples collected from febrile patients for measles and rubella surveillance between 2009 and 2015 in 127 districts of Mozambique were retrospectively tested for IgM and IgG antibodies against CHIKV using a commercially available ELISA.

Results

The median age of patients was 2 years (IQR: 1–5 years) and 44.2% (395/895) of them were female. We found that 54 (6.0%) of samples were positive for anti-IgM chikungunya, and 160 (17.9%) were positive for anti-CHIKV IgG. Antibodies against CHIKV (IgM and IgG) were identified in serum throughout 2009 to 2015. While frequency of IgG antibodies was significantly higher in 2015 as compared to other years, frequency of IgM antibodies was homogeneous between 2009 and 2015. Antibodies against CHIKV were reported in all provinces and in 84 (66.1%) of the districts studied. Frequency of IgM and IgG antibodies was not significantly similar between age groups.

Conclusion

This is the largest and longest serological screening of antibodies against CHIKV in febrile patients in Mozambique and findings from this study suggest that Mozambicans from all over the country have been silently exposed to CHIKV for several years.

Going Viral 2019: Zika, Chikungunya, and Dengue

Chikungunya and Zika virus infections are emerging diseases in the Americas, and dengue continues to be the most prevalent arthropod-borne virus in the world. These arbovirus diseases may spread by endemic transmission or as travel-related infections and have rapidly expanded their geographic distribution secondary to vector spread. All 3 share a similar clinical picture that includes a maculopapular rash. Zika is characterized by pruritic rash, low-grade fever, and arthralgia. Congenital nervous system malformations are a growing public-health concern. Chikungunya distinctive dermatologic manifestations include facial melanosis and bullous eruption. Dengue bleeding complications may be life-threatening and require inpatient management.

Chikungunya virus infection in Indonesia: a systematic review and evolutionary analysis

Background

Despite the high number of chikungunya cases in Indonesia in recent years, comprehensive epidemiological data are lacking. The systematic review was undertaken to provide data on incidence, the seroprevalence of anti-Chikungunya virus (CHIKV) IgM and IgG antibodies, mortality, the genotypes of circulating CHIKV and travel-related cases of chikungunya in the country. In addition, a phylogenetic and evolutionary analysis of Indonesian CHIKV was conducted.

Methods

A systematic review was conducted to identify eligible studies from EMBASE, MEDLINE, PubMed and Web of Science as of October 16th 2017. Studies describing the incidence, seroprevalence of IgM and IgG, mortality, genotypes and travel-associated chikungunya were systematically reviewed. The maximum likelihood phylogenetic and evolutionary rate was estimated using Randomized Axelerated Maximum Likelihood (RAxML), and the Bayesian Markov chain Monte Carlo (MCMC) method identified the Time to Most Recent Common Ancestors (TMRCA) of Indonesian CHIKV. The systematic review was registered in the PROSPERO database (CRD42017078205).

Results

Chikungunya incidence ranged between 0.16-36.2 cases per 100,000 person-year. Overall, the median seroprevalence of anti-CHIKV IgM antibodies in both outbreak and non-outbreak scenarios was 13.3% (17.7 and 7.3% for outbreak and non-outbreak events, respectively). The median seroprevalence of IgG antibodies in both outbreak and non-outbreak settings was 18.5% (range 0.0–73.1%). There were 130 Indonesian CHIKV sequences available, of which 120 (92.3%) were of the Asian genotype and 10 (7.7%) belonged to the East/Central/South African (ECSA) genotype. The ECSA genotype was first isolated in Indonesia in 2008 and was continually sampled until 2011. All ECSA viruses sampled in Indonesia appear to be closely related to viruses that caused massive outbreaks in Southeast Asia countries during the same period. Massive nationwide chikungunya outbreaks in Indonesia were reported during 2009–2010 with a total of 137,655 cases. Our spatio-temporal, phylogenetic and evolutionary data suggest that these outbreaks were likely associated with the introduction of the ECSA genotype of CHIKV to Indonesia.

Conclusions

Although no deaths have been recorded, the seroprevalence of anti-CHIKV IgM and IgG in the Indonesian population have been relatively high in recent years following re-emergence in early 2001. There is sufficient evidence to suggest that the introduction of ECSA into Indonesia was likely associated with massive chikungunya outbreaks during 2009–2010.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-3857-y) contains supplementary material, which is available to authorized users.

Emerging and threatening vector-borne zoonoses in the world and in Europe: a brief update

Climatic changes, landscape management, massive human, animal and commodity transportation represent important factors which are contributing to the spread of zoonotic diseases. The environmental and socioeconomic factors affecting the incidence of vector-borne zoonoses and possibilities for the reduction of disease impacts are discussed in the article. The most important zoonoses with expanding area of incidence and/or increasing occurrence are summarized, with special emphasis on the European region. While some diseases and their respective pathogens are indigenous to Europe (e.g. Lyme disease), others have been introduced to Europe from tropical areas (e.g. chikungunya or dengue fever). These emerging diseases may represent a serious threat in near future and better understanding of their spreading mechanisms, pathogenesis and consequent treatment is very important.

A comparison of mosquito densities, weather and infection rates of Aedes aegypti during the first epidemics of Chikungunya (2014) and Zika (2016) in areas with and without vector control in Puerto Rico

In Puerto Rico, the first records of the transmission of Chikungunya (CHIKV) and Zika (ZIKV) viruses were confirmed in May 2014 and December 2015, respectively. Transmission of CHIKV peaked in September 2014, whereas that of ZIKV peaked in August 2016. The emergence of these mosquito-transmitted arboviruses in the context of a lack of human population immunity allowed observations of whether the outbreaks were associated with Aedes aegypti (Diptera: Culicidae) densities and weather. Mosquito density was monitored weekly in four communities using sentinel autocidal gravid ovitraps (AGO traps) during 2016 in order to provide data to be compared with the findings of a previous study carried out during the 2014 CHIKV epidemic. Findings in two communities protected against Ae. aegypti using mass AGO trapping (three traps per house in most houses) were compared with those in two nearby communities without vector control. Mosquito pools were collected to detect viral RNA of ZIKV, CHIKV and dengue virus. In areas without vector control, mosquito densities and rates of ZIKV detection in 2016 were significantly higher, similarly to those observed for CHIKV in 2014. The density of Ae. aegypti in treated sites was less than two females/trap/week, which is similar to the putative adult female threshold for CHIKV transmission. No significant differences in mosquito density or infection rates with ZIKV and CHIKV at the same sites between years were observed. Although 2016 was significantly wetter, mosquito densities were similar.

Identification of Broad-Spectrum Antiviral Compounds by Targeting Viral Entry

Viruses are a major threat to human health and economic well-being. In recent years Ebola, Zika, influenza, and chikungunya virus epidemics have raised awareness that infections can spread rapidly before vaccines or specific antagonists can be made available. Broad-spectrum antivirals are drugs with the potential to inhibit infection by viruses from different groups or families, which may be deployed during outbreaks when specific diagnostics, vaccines or directly acting antivirals are not available. While pathogen-directed approaches are generally effective against a few closely related viruses, targeting cellular pathways used by multiple viral agents can have broad-spectrum efficacy. Virus entry, particularly clathrin-mediated endocytosis, constitutes an attractive target as it is used by many viruses. Using a phenotypic screening strategy where the inhibitory activity of small molecules was sequentially tested against different viruses, we identified 12 compounds with broad-spectrum activity, and found a subset blocking viral internalisation and/or fusion. Importantly, we show that compounds identified with this approach can reduce viral replication in a mouse model of Zika infection. This work provides proof of concept that it is possible to identify broad-spectrum inhibitors by iterative phenotypic screenings, and that inhibition of host-pathways critical for viral life cycles can be an effective antiviral strategy.

Molecular epidemiology of dengue, yellow fever, Zika and Chikungunya arboviruses: An update

Arboviruses are a group of viruses transmitted by arthropods. They are characterized by a wide geographic distribution, which is associated with the presence of the vector, and cause asymptomatic infections or febrile diseases in humans in both enzootic and urban cycles. Recent reports of human infections caused by viruses such as dengue, Zika, and chikungunya have raised concern regarding public health, and have led to the re-evaluation of surveillance mechanisms and measures to control the transmission of these arboviruses. Viruses such as Mayaro and Usutu are not currently responsible for a high number of symptomatic infections in humans, but should remain under epidemiological surveillance to avoid the emergence of new epidemics, as happened with Zika virus, that are associated with new or more severe symptoms. Additionally, significant variation has been observed in these viruses, giving rise to different lineages. Until recently, the emergence of new lineages has primarily been related to geographical distribution and dispersion, allowing us to ascertain the possible origins and direction of expansion of each virus type, and to make predictions regarding regions where active infections in humans are likely to occur. Therefore, this review is focused on untangling the molecular epidemiology of Dengue, Yellow fever, Zika and Chikungunya due to their recent epidemics in Latinamerica but provides an update on the geographical distribution globally of these viral variants, and outlines the need for further understanding of the genotypes/lineages assignment.

Isatin Derivatives and Their Antiviral Properties Against Arboviruses: A Review

Arboviruses have been spreading rapidly throughout the Western Hemisphere in recent decades. Among the arboviruses with high morbidity and mortality are the members of the Alphavirus and Flavivirus genera. Within the first genus, Chikungunya Virus (CHIKV) is considered one of the most challenging human arboviral infection worldwide, against which there is no specific antivirals. Flaviviruses are some of the main viruses responsible for encephalitis, haemorrhagic disease and developmental defects. Dengue virus (DENV), Japanese Encephalitis Virus (JEV), West Nile Virus (WNV) and Zika Virus (ZIKV) are examples of flaviviruses without clinically approved antiviral agents. Thus, the search for new antivirals becomes highly important. One of the strategies that can be employed to obtain new drugs is the identification and utilization of privileged structures. Isatin is an example of a privileged molecular framework, displaying a broad spectrum of biological activities, including antiviral action. Obtaining and studying the antiviral properties of isatin derivatives have helped to identify important agents with potential activity against different arboviruses. This article reviews some of these isatin derivatives, their structures and antiviral properties reported against this important group of viruses.

Emerging infectious uveitis: Chikungunya, dengue, Zika and Ebola: A review

Recently recognized forms of uveitis include intraocular inflammations that occur during or following one of several emerging infectious diseases: chikungunya fever, dengue, Zika virus disease and Ebola virus disease. Anterior, intermediate, posterior and pan-uveitis have been described in individuals infected with chikungunya virus. Persons who contract dengue or Zika viruses also may develop different types of uveitis in the course of the infection: maculopathy is a common manifestation of dengue eye disease, and Zika eye disease may cause hypertensive anterior uveitis or mimic a white dot syndrome. Up to one-third of Ebola survivors develop aggressive uveitis, which is frequently associated with vision loss and complicated by cataract. There are no specific anti-viral drugs for these forms of uveitis, and thus treatment is largely supportive. In this article, we summarize the systemic infectious diseases and virology, and describe the clinical presentations, outcomes and management of emerging viral forms of uveitis.

Islands as Hotspots for Emerging Mosquito-Borne Viruses: A One-Health Perspective

During the past ten years, an increasing number of arbovirus outbreaks have affected tropical islands worldwide. We examined the available literature in peer-reviewed journals, from the second half of the 20th century until 2018, with the aim of gathering an overall picture of the emergence of arboviruses in these islands. In addition, we included information on environmental and social drivers specific to island setting that can facilitate the emergence of outbreaks. Within the context of the One Health approach, our review highlights how the emergence of arboviruses in tropical islands is linked to the complex interplay between their unique ecological settings and to the recent changes in local and global sociodemographic patterns. We also advocate for greater coordination between stakeholders in developing novel prevention and mitigation approaches for an intractable problem.

Historical Perspective of Arboviruses in Mozambique and Its Implication for Current and Future Epidemics

Mozambique is a tropical country situated in the Southern part of Africa, a region where data on the burden and epidemiology of arbovirus is presently quite scarce although the frequency of outbreaks caused by arboviruses is rapidly increasing. Outbreaks of dengue fever have been reported in Mozambique, Angola and Tanzania and a recent unprecedented outbreak of Yellow fever has been recorded in Angola. These new outbreaks collectively suggest that arboviruses, and specifically flavivirus infections, are endemic in Mozambique.Although recent data on arbovirus activity is scarce, the work of Kokernot et al. [R.H. Kokernot, K.C. Smithburn, A.F. Gandara, B.M. Mc'Intosh and C.S. Heymann Anais Inst Med Trop (1960), 17:201-230] describes seroepidemiological and entomological studies carried out in several parts of Mozambique during the 1950s. Complementary seroepidemiological investigations on arboviruses that were conducted in the early 1980s also found serological evidence of several arboviruses which included Dengue, Chikungunya, Zika, Rift Valey Fever, Sinbdis virus, Wesselsbron, Bunyamwera, Pongola and Bawamba Fever and Yellow Fever.Notably the first description of Chikungunya virus in 1952-1953 in Tanzania also included reported cases in northern Mozambique. Furthermore, DENV serotype 3 was for the first time described in northern Mozambique in 1984 and 1985. Since several arboviral infections result in acute self limiting fever they have remained unsuspected for several decades. However, it is well known that during the 1980's intensive malaria control initiatives which included massive distribution of bed nets, community education and indoor and outdoor spraying campaigns were implemented. It is possible that these measures may have influenced the epidemiology of arboviruses. However, the impact of these interventions in controlling the spread of arboviruses is not known.In conclusion, the old literature on arboviruses in Mozambique is relevant for assessing the gaps and current risk of occurrence of these pathogens at the region, particularly in a time in which they are spreading worldwide.