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

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

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that is emerging as a global threat because of the highly debilitating nature of the associated disease and unprecedented magnitude of its spread. Chikungunya originated in Africa and has since spread across the entire globe causing large numbers of epidemics that have infected millions of people in Asia, the Indian subcontinent, Europe, the Americas, and Pacific Islands. Phylogenetic analysis has identified four different genotypes of CHIKV: Asian, West African, East/Central/South African (ECSA), and Indian Ocean Lineage (IOL). In the absence of well-designed epidemiological studies, the aim of this review article was to summarize the global epidemiology of CHIKV and to provide baseline data for future research on the treatment, prevention, and control of this life-threatening disease.

Tissue tropism of Saint Louis encephalitis virus: Histopathology triggered by epidemic and non-epidemic strains isolated in Argentina

Saint Louis encephalitis virus (SLEV) reemerged in South America, and caused encephalitis outbreaks at the beginning of the 21st century. To enhance our knowledge about SLEV virulence, we performed comparative pathogenesis studies in Swiss albino mice inoculated with two different variants, the epidemic strain CbaAr-4005 and the non-epidemic strain CorAn-9275. Only the infection of mice with SLEV strain CbaAr-4005 resulted in high viremia, invasion of peripheral tissues including the lungs, kidney, and spleen, and viral neuroinvasion. This was associated with inflammatory pathology in the lungs, spleen, and brain as well as morbidity and mortality. In contrast, neither signs of desease nor viral replication were observed in mice infected with strain CorAn-9275. Interestingly, important loss of B cells and development of altered germinal centers (GC) were detected in the spleen of mice infected with strain CbaAr-4005, whereas mice infected with SLEV CorAn-9275 developed prominent GC with conserved follicular architecture, and neutralizing antibodies.

Chikungunya virus: epidemiology, replication, disease mechanisms, and prospective intervention strategies

Chikungunya virus (CHIKV), a reemerging arbovirus, causes a crippling musculoskeletal inflammatory disease in humans characterized by fever, polyarthralgia, myalgia, rash, and headache. CHIKV is transmitted by Aedes species of mosquitoes and is capable of an epidemic, urban transmission cycle with high rates of infection. Since 2004, CHIKV has spread to new areas, causing disease on a global scale, and the potential for CHIKV epidemics remains high. Although CHIKV has caused millions of cases of disease and significant economic burden in affected areas, no licensed vaccines or antiviral therapies are available. In this Review, we describe CHIKV epidemiology, replication cycle, pathogenesis and host immune responses, and prospects for effective vaccines and highlight important questions for future research.

Global distribution and environmental suitability for chikungunya virus, 1952 to 2015

Chikungunya fever is an acute febrile illness caused by the chikungunya virus (CHIKV), which is transmitted to humans by Aedes mosquitoes. Although chikungunya fever is rarely fatal, patients can experience debilitating symptoms that last from months to years. Here we comprehensively assess the global distribution of chikungunya and produce high-resolution maps, using an established modelling framework that combines a comprehensive occurrence database with bespoke environmental correlates, including up-to-date Aedes distribution maps. This enables estimation of the current total population-at-risk of CHIKV transmission and identification of areas where the virus may spread to in the future. We identified 94 countries with good evidence for current CHIKV presence and a set of countries in the New and Old World with potential for future CHIKV establishment, demonstrated by high environmental suitability for transmission and in some cases previous sporadic reports. Aedes aegypti presence was identified as one of the major contributing factors to CHIKV transmission but significant geographical heterogeneity exists. We estimated 1.3 billion people are living in areas at-risk of CHIKV transmission. These maps provide a baseline for identifying areas where prevention and control efforts should be prioritised and can be used to guide estimation of the global burden of CHIKV.

Zika and chikungunya: mosquito-borne viruses in a changing world

The reemergence and growing burden of mosquito-borne virus infections have incited public fear and growing research efforts to understand the mechanisms of infection-associated health outcomes and to provide better approaches for mosquito vector control. While efforts to develop therapeutics, vaccines, and novel genetic mosquito-control technologies are underway, many important underlying ecological questions remain that could significantly enhance our understanding and ability to predict and prevent transmission. Here, we review the current knowledge about the transmission ecology of two recent arbovirus invaders, the chikungunya and Zika viruses. We introduce the viruses and mosquito vectors, highlighting viral biology, historical routes of transmission, and viral mechanisms facilitating rapid global invasion. In addition, we review factors contributing to vector global invasiveness and transmission efficiency. We conclude with a discussion of how human-induced biotic and abiotic environmental changes facilitate mosquito-borne virus transmission, emphasizing critical gaps in understanding. These knowledge gaps are tremendous; much of our data on basic mosquito ecology in the field predate 1960, and the mosquitoes themselves, as well as the world they live in, have substantially changed. A concerted investment in understanding the basic ecology of these vectors, which serve as the main drivers of pathogen transmission in both wildlife and human populations, is now more important than ever.

Potential entry inhibitors of the envelope protein (E2) of Chikungunya virus: in silico structural modeling, docking and molecular dynamic studies

Chikungunya fever is an arboviral infection caused by the Chikungunya virus (CHIKV) and is transmitted by Aedes mosquito. The envelope protein (E2) of Chikungunya virus is involved in attachment of virion with the host cell. The present study was conceptualized to determine the structure of E2 protein of CHIKV and to identify the potential viral entry inhibitors. The secondary and tertiary structure of E2 protein was determined using bioinformatics tools. The mutational analysis of the E2 protein suggested that mutations may stabilize or de-stabilize the structure which may affect the structure-function relationship. In silico screening of various compounds from different databases identified two lead molecules i.e. phenothiazine and bafilomycin. Molecular docking and MD simulation studies of the E2 protein and compound complexes was carried out. This analysis revealed that bafilomycin has high docking score and thus high binding affinity with E2 protein suggesting stable protein-ligand interaction. Further, MD simulations suggested that both the compounds were stabilizing E2 protein. Thus, bafilomycin and phenothiazine may be considered as the lead compounds in terms of potential entry inhibitor for CHIKV. Further, these results should be confirmed by comprehensive cell culture, cytotoxic assays and animal experiments. Certain derivatives of phenothiazines can also be explored in future studies for entry inhibitors against CHIKV. The present investigation thus provides insight into protein structural dynamics of the envelope protein of CHIKV. In addition the study also provides information on the dynamics of interaction of E2 protein with entry inhibitors that will contribute towards structure based drug design.

Chikungunya Infection: a Global Public Health Menace

Chikungunya virus (CHIKV) has been involved in epidemics in African and Asian subcontinents and, of late, has transcended to affect the Americas. Aedes aegypti and Aedes albopictus are the major vectors for CHIKV infection, which results in dissemination of virus to various vital organs. Entry of virus into these tissues causes infiltration of innate immune cells, monocytes, macrophages, neutrophils, natural killer cells, and adaptive immune cells. Macrophages bearing the replicating virus, in turn, secrete pro-inflammatory cytokines IL-1β, TNF-α, and IL-17. Together, this pro-inflammatory milieu induces osteoclastogenesis, bone loss, and erosion. CHIKV is characterized by fever, headache, myalgia, rash, and symmetric polyarthritis, which is generally self-limiting. In a subset of cases, however, musculoskeletal symptoms may persist for up to 3-5 years. Viral culture and isolation from blood cells of infected patients are the gold standards for diagnosis of CHIKV. In routine practice, however, assays for anti-CHIKV IgM antibodies are used for diagnosis, as elevated levels in blood of infected patients are noted from 10 days following infection for up to 3-6 months. Early diagnosis of CHIKV is possible by nucleic acid detection techniques. Treatment of acute CHIKV is mainly symptomatic, with analgesics, non-steroidal anti-inflammatory agents (NSAIDs), and low-dose steroids. No vaccines or anti-viral medicines have been approved for clinical therapy in CHIKV as yet. Hydroxychloroquine and methotrexate have been used in chronic CHIKV infection with variable success.

Regulation of Viral Replication, Apoptosis and Pro-Inflammatory Responses by 17-AAG during Chikungunya Virus Infection in Macrophages

Chikungunya virus (CHIKV) infection has re-emerged as a major public health concern due to its recent worldwide epidemics and lack of control measures. Although CHIKV is known to infect macrophages, regulation of CHIKV replication, apoptosis and immune responses towards macrophages are not well understood. Accordingly, the Raw264.7 cells, a mouse macrophage cell line, were infected with CHIKV and viral replication as well as new viral progeny release was assessed by flow cytometry and plaque assay, respectively. Moreover, host immune modulation and apoptosis were studied through flow cytometry, Western blot and ELISA. Our current findings suggest that expression of CHIKV proteins were maximum at 8 hpi and the release of new viral progenies were remarkably increased around 12 hpi. The induction of Annexin V binding, cleaved caspase-3, cleaved caspase-9 and cleaved caspase-8 in CHIKV infected macrophages suggests activation of apoptosis through both intrinsic and extrinsic pathways. The pro-inflammatory mediators (TNF and IL-6) MHC-I/II and B7.2 (CD86) were also up-regulated during infection over time. Further, 17-AAG, a potential HSP90 inhibitor, was found to regulate CHIKV infection, apoptosis and pro-inflammatory cytokine/chemokine productions of host macrophages significantly. Hence, the present findings might bring new insight into the therapeutic implication in CHIKV disease biology.

Structure-function relationship of Chikungunya nsP2 protease: A comparative study with papain

Chikungunya virus is a growing human pathogen transmitted by mosquito bite. It causes fever, chills, nausea, vomiting, joint pain, headache, and swelling in the joints. Its replication and propagation depend on the protease activity of the Chikungunya virus-nsP2 protein, which cleaves the nsP1234 polyprotein replication complex into individual functional units. The N-terminal segment of papain is structurally identical with the Chikungunya virus-nsP2 protease. Hence, molecular dynamics simulations were performed to compare molecular mechanism of these proteases. The Chikungunya virus-snP2 protease shows more conformational changes and adopts an alternate conformation. However, N-terminal segment of these two proteases has identical active site scaffold with the conserved catalytic diad. Hence, some of the non-peptide inhibitors of papain were used for induced fit docking at the active site of the nsP2 to assess the binding mode. In addition, the peptides that connect different domains/protein in Chikungunya virus poly-protein were also subjected for docking. The overall results suggest that the active site scaffold is the same in both the proteases and a possibility exists to experimentally assess the efficacy of some of the papain inhibitors to inhibit the Chikungunya virus-nsP2.

Spectral characterisation, antiviral activities, in silico ADMET and molecular docking of the compounds isolated from Tectona grandis to chikungunya virus

Chikungunya infection is treated symptomatically with antipyretics and anti-inflammatory drugs without any specific antiviral drug till date. The lack of an approved antiviral drug and the emergence of virulent strains after 2006 epidemics emphasize the need for the development of potential antiviral drugs to Chikungunya virus. Hence, we studied the antiviral activity of the extracts and compounds isolated from Tectona grandis leaves to both the Asian and East central South African strains of Chikungunya virus. Five compounds were isolated from the ethanolic extract of Tectona grandis by bioactivity guided fractionation followed by Spectral Characterisation through GC-MS and NMR spectroscopy and investigated for the antiviral activity. Also in silico ADMET and Molecular Docking of the characterised compounds against the structural and non structural proteins of Chikungunya virus were performed. The characterised compound Benzene-1-carboxylic acid hexadeconate was effective at IC 50 3.036μg/ml (7.5μM) and 76.46μg/ml (189.02μM) to Asian and ECSA strain of CHIKV respectively. The compound showed desirable pharmacokinetic properties and significant molecular interactions with the E1 protein of Chikungunya virus by in silico analysis. Thus Benzene-1-carboxylic acid-2-hexadeconate isolated from Tectona grandis was found to be a promising drug candidate to both the Asian and ECSA strains of Chikungunya virus with high selectivity indices in comparison to the reference RNA antiviral drug Ribavirin.

Evolutionary ecology of virus emergence

The cross-species transmission of viruses into new host populations, termed virus emergence, is a significant issue in public health, agriculture, wildlife management, and related fields. Virus emergence requires overlap between host populations, alterations in virus genetics to permit infection of new hosts, and adaptation to novel hosts such that between-host transmission is sustainable, all of which are the purview of the fields of ecology and evolution. A firm understanding of the ecology of viruses and how they evolve is required for understanding how and why viruses emerge. In this paper, I address the evolutionary mechanisms of virus emergence and how they relate to virus ecology. I argue that, while virus acquisition of the ability to infect new hosts is not difficult, limited evolutionary trajectories to sustained virus between-host transmission and the combined effects of mutational meltdown, bottlenecking, demographic stochasticity, density dependence, and genetic erosion in ecological sinks limit most emergence events to dead-end spillover infections. Despite the relative rarity of pandemic emerging viruses, the potential of viruses to search evolutionary space and find means to spread epidemically and the consequences of pandemic viruses that do emerge necessitate sustained attention to virus research, surveillance, prophylaxis, and treatment.

Epidemiology of Chikungunya in the Americas

Chikungunya virus (CHIKV) emerged in the Americas in late 2013 to cause substantial acute and chronic morbidity. About 1.1 million cases of chikungunya were reported within a year, including severe cases and deaths. The burden of chikungunya is unclear owing to inadequate disease surveillance and underdiagnosis. Virus evolution, globalization, and climate change may further CHIKV spread. No approved vaccine or antiviral therapeutics exist. Early detection and appropriate management could reduce the burden of severe atypical and chronic arthritic disease. Improved surveillance and risk assessment are needed to mitigate the impact of chikungunya.

Interferon regulatory factor 2 protects mice from lethal viral neuroinvasion

Li et al. describe a novel role for IRF2, previously known as a negative regulator of type I IFN signaling, in protection of mice from lethal viral neuroinvasion by facilitating the proper localization of B cells and antibodies to the central nervous system.

The host responds to virus infection by activating type I interferon (IFN) signaling leading to expression of IFN-stimulated genes (ISGs). Dysregulation of the IFN response results in inflammatory diseases and chronic infections. In this study, we demonstrate that IFN regulatory factor 2 (IRF2), an ISG and a negative regulator of IFN signaling, influences alphavirus neuroinvasion and pathogenesis. A Sindbis virus strain that in wild-type (WT) mice only causes disease when injected into the brain leads to lethal encephalitis in Irf2^−/− mice after peripheral inoculation. Irf2^−/− mice fail to control virus replication and recruit immune infiltrates into the brain. Reduced B cells and virus-specific IgG are observed in the Irf2^−/− mouse brains despite the presence of peripheral neutralizing antibodies, suggesting a defect in B cell trafficking to the central nervous system (CNS). B cell–deficient μMT mice are significantly more susceptible to viral infection, yet WT B cells and serum are unable to rescue the Irf2^−/− mice. Collectively, our data demonstrate that proper localization of B cells and local production of antibodies in the CNS are required for protection. The work advances our understanding of host mechanisms that affect viral neuroinvasion and their contribution to immunity against CNS infections.

Knowledge, Attitude and Practices of Vector-Borne Disease Prevention during the Emergence of a New Arbovirus: Implications for the Control of Chikungunya Virus in French Guiana

Background

During the last decade, French Guiana has been affected by major dengue fever outbreaks. Although this arbovirus has been a focus of many awareness campaigns, very little information is available about beliefs, attitudes and behaviors regarding vector-borne diseases among the population of French Guiana. During the first outbreak of the chikungunya virus, a quantitative survey was conducted among high school students to study experiences, practices and perceptions related to mosquito-borne diseases and to identify socio-demographic, cognitive and environmental factors that could be associated with the engagement in protective behaviors.

Methodology/Principal Findings

A cross-sectional survey was administered in May 2014, with a total of 1462 students interviewed. Classrooms were randomly selected using a two-stage selection procedure with cluster samples. A multiple correspondence analysis (MCA) associated with a hierarchical cluster analysis and with an ordinal logistic regression was performed. Chikungunya was less understood and perceived as a more dreadful disease than dengue fever. The analysis identified three groups of individual protection levels against mosquito-borne diseases: “low” (30%), “moderate” (42%) and “high” (28%)”. Protective health behaviors were found to be performed more frequently among students who were female, had a parent with a higher educational status, lived in an individual house, and had a better understanding of the disease.

Conclusions/Significance

This study allowed us to estimate the level of protective practices against vector-borne diseases among students after the emergence of a new arbovirus. These results revealed that the adoption of protective behaviors is a multi-factorial process that depends on both sociocultural and cognitive factors. These findings may help public health authorities to strengthen communication and outreach strategies, thereby increasing the adoption of protective health behaviors, particularly in high-risk populations.

Although dengue fever has been a focus of many awareness campaigns in Latin America, very little information is available about beliefs, attitudes and behaviors regarding vector-borne diseases among the population of French Guiana. At the initial onset of the first chikungunya outbreak, a quantitative survey was conducted among 1462 high school students aiming to study experiences, practices and perceptions related to mosquito-borne diseases and to identify factors that could be associated with protective behaviors. Chikungunya was less understood and perceived as a more dreadful disease than dengue fever. Students were clustered in three different groups according to their level of protection: “low” (30%), “moderate” (42%) and “high” (28%). Protective health behaviors were found to be performed more frequently among students who were female, lived with a parent who had a higher educational status, lived in an individual house, and had a better understanding of the disease. The results revealed that the adoption of protective behaviors is a multi-factorial process that depends on both socio-economic and cognitive factors. These findings may help the public health authorities to strengthen their communication and outreach strategy, thereby increasing the adoption of protective health behaviors, particularly in endemic countries and high-risk populations.

Physiotherapeutic approach on the late phase of chikungunya: a case report

Abstract Introduction: in April of 2016, the epidemiological bulletin reported 39,017 suspected cases of chikungunya fever in Brazil. The main symptoms of the disease in the acute phase are: high fever, polyarthralgia, back pain, headache and fatigue; while in the late phase present polyarthralgia or musculoskeletal pain which often has prolonged duration. Description: in the late phase, the patient presented complaints mainly of: severe pain on the ankle joints wrists, elbows and shoulders. The medical handling consisted of continuous ultrasound sessions with the frequency of 1 MHz. The infrared laser with a dosage of 4J and 3s per point; TENS-burst with a pulse width of 250 us and the frequency of 2Hz, carried out for 10 days. The physiotherapeutic treatment proposal was an innovation, however there are no medical literatures for completementary medication for the treatment which could reduce the use of analgesics and could cause prolonged comfort to the patient ratified by EVA and the SF-36. Discussion: the use of ultrasound and low intensity laser are performed on the signs of chronic articular treatment in order to reduce inflammation, pain and joint stiffness. Therefore, a remarkable reduction of the algic state and the improvement of the patient's life along the r ten consecutive sessions of a proposed protocol in this study, thus there is a need for further researches on this issue so it is possible to perform a medical handling based on evidences on the theme.

Dysregulated TGF-β Production Underlies the Age-Related Vulnerability to Chikungunya Virus

Chikungunya virus (CHIKV) is a re-emerging global pathogen with pandemic potential, which causes fever, rash and debilitating arthralgia. Older adults over 65 years are particularly susceptible to severe and chronic CHIKV disease (CHIKVD), accounting for >90% of all CHIKV-related deaths. There are currently no approved vaccines or antiviral treatments available to limit chronic CHIKVD. Here we show that in old mice excessive, dysregulated TGFβ production during acute infection leads to a reduced immune response and subsequent chronic disease. Humans suffering from CHIKV infection also exhibited high TGFβ levels and a pronounced age-related defect in neutralizing anti-CHIKV antibody production. In vivo reduction of TGFβ levels minimized acute joint swelling, restored neutralizing antibody production and diminished chronic joint pathology in old mice. This study identifies increased and dysregulated TGFβ secretion as one key mechanism contributing to the age-related loss of protective anti-CHIKV-immunity leading to chronic CHIKVD.

Evaluation of Two Enzyme-Linked Immunosorbent Assay Kits for Chikungunya Virus IgM Using Samples from Deceased Organ and Tissue Donors

The identification of nearly 3,500 cases of chikungunya virus (CHIKV) infection in U.S. residents returning in 2014 and 2015 from areas in which it is endemic has raised concerns within the transplant community that, should recently infected individuals become organ and/or tissue donors, CHIKV would be transmitted to transplant recipients. Thus, tests designed to detect recent CHIKV infection among U.S. organ and tissue donors may become necessary in the future. Accordingly, we evaluated 2 enzyme-linked immunosorbent assays (ELISAs) for CHIKV IgM readily available in the United States using 1,000 deidentified serum or plasma specimens collected from donors between November 2014 and March 2015. The Euroimmun indirect ELISA identified 38 reactive specimens; however, all 38 were negative for CHIKV IgG and IgM in immunofluorescence assays (IFAs) conducted at a reference laboratory and, thus, were falsely reactive in the Euroimmun CHIKV IgM assay. The InBios IgM-capture ELISA identified 26 reactive samples, and one was still reactive (index ≥ 1.00) when retested using the InBios kit with a background subtraction modification to identify false reactivity. This reactive specimen was CHIKV IgM negative but IgG positive by IFAs at two reference laboratories; plaque reduction neutralization testing (PRNT) demonstrated CHIKV-specific reactivity. The IgG and PRNT findings strongly suggest that the InBios CHIKV IgM-reactive result represents true reactivity, even though the IgM IFA result was negative. If testing organ/tissue donors for CHIKV IgM becomes necessary, the limitations of the currently available CHIKV IgM ELISAs and options for their optimization must be understood to avoid organ/tissue wastage due to falsely reactive results.

A Field-Deployable Reverse Transcription Recombinase Polymerase Amplification Assay for Rapid Detection of the Chikungunya Virus

Background

Chikungunya virus (CHIKV) is a mosquito-borne virus currently transmitted in about 60 countries. CHIKV causes acute flu-like symptoms and in many cases prolonged musculoskeletal and joint pain. Detection of the infection is mostly done using RT-RCR or ELISA, which are not suitable for point-of-care diagnosis.

Methodology/Principal Findings

In this study, a reverse transcription recombinase polymerase amplification (RT-RPA) assay for the detection of the CHIKV was developed. The assay sensitivity, specificity, and cross-reactivity were tested. CHIKV RT-RPA assay detected down to 80 genome copies/reaction in a maximum of 15 minutes. It successfully identified 18 isolates representing the three CHIKV genotypes. No cross-reactivity was detected to other alphaviruses and arboviruses except O'nyong'nyong virus, which could be differentiated by a modified RPA primer pair. Seventy-eight samples were screened both by RT-RPA and real-time RT-PCR. The diagnostic sensitivity and specificity of the CHIKV RT-RPA assay were determined at 100%.

Conclusions/Significance

The developed RT-RPA assay represents a promising method for the molecular detection of CHIKV at point of need.

CHIKV is transmitted to humans via mosquitos. CHIKV induces clinical signs similar to Influenza, Dengue, and Zika viruses. We have developed a molecular assay for the detection of CHIKV genome based on isothermal„recombinase polymerase amplification (RPA) assay”performed at 42°C. The result was obtained in maximum of 15 minutes, which is 4–6 times faster than the current molecular diagnostic techniques. Our CHIKV RPA assay is rapid and sensitive, as well as easy to use at the point of need.

The spread of Zika and the potential for global arbovirus syndemics

It is estimated that over a million people die each year from infectious diseases of zoonotic origin and hundreds of millions suffer from these pervasive threats to human well-being. In light of the emergent global concern over the Zika virus, evidence that it has not one but two competent mosquito vector species in the Aedes family, and that both can be co-infected with other pathogens including dengue and chikungunya, this paper examines research suggesting the prospect of significant twenty-first-century outbreaks of arbovirus syndemics. Uniting the concepts 'synergy' with 'epidemic', a syndemics approach recognises that diseases in a population occur neither independent of social and ecological conditions, nor in isolation from other diseases. Assessment of the potential for arbovirus syndemics entails a review of the human role in the global spread of Aedes mosquitoes, the socio-environmental conditions of Aedes diffusion, the increasing likelihood of co-transmission of arbovirus diseases, evidence of co-infection and concern about the adverse health effects of arbovirus syndemic interaction, and the need for an appropriate environment-sensitive framework for effective public health responses. Called Planetary Health, this emergent framework confronts conceptual, knowledge, and governance challenges created by the dramatic shifts in environments, climates, people, vectors, and pathogens in the world.

First Complete Genome Sequence of a Chikungunya Virus Strain Isolated from a Patient Diagnosed with Dengue Virus Infection in Malaysia

Here, we report the complete genome sequence of a chikungunya virus coinfection strain isolated from a dengue virus serotype 2-infected patient in Malaysia. This coinfection strain was determined to be of the Asian genotype and contains a novel insertion in the nsP3 gene.

Clinical and Serological Insights from the Asian Lineage Chikungunya Outbreak in Grenada, 2014: An Observational Study

Chikungunya virus (CHIKV) spread rapidly throughout the Caribbean region in 2014, and the first serologically confirmed case was seen in Grenada in July. This study investigated the outbreak of CHIKV in Grenada to identify the distinguishing clinical manifestations and the symptoms that corresponded the closest with serological test results. Sera were tested by IgM enzyme-linked immunosorbent assay and polymerase chain reaction to distinguish between cases positive or negative for CHIKV. Of 493 cases, 426 (86%) tested positive for CHIKV. The diagnostic decision rule, "Define as CHIKV positive a patient presenting with joint pain and any combination of fever, body pain, or rash," produced the closest agreement (85%) with the serological test results (Cohen's kappa, k = 0.289, P value < 0.001). When laboratory facilities are not available for diagnostic confirmation, syndromic surveillance using these four symptoms could be useful to define cases during a CHIKV outbreak when CHIKV is the predominant circulating arbovirus.

Dengue and chikungunya viruses in plasma are effectively inactivated after treatment with methylene blue and visible light

BACKGROUND

Arboviruses, such as dengue viruses (DENV) and chikungunya virus (CHIKV), pose a risk to the safe transfusion of blood components, including plasma. Pathogen inactivation is an approach to manage this transfusion transmission risk, with a number of techniques being used worldwide for the treatment of plasma. In this study, the efficacy of the THERAFLEX MB-Plasma system to inactivate all DENV serotypes (DENV-1, DENV-2, DENV-3, DENV-4) or CHIKV in plasma, using methylene blue and light illumination at 630 nm, was investigated.

STUDY DESIGN AND METHODS

Pooled plasma units were spiked with DENV-1, DENV-2, DENV-3 DENV-4, or CHIKV and treated with the THERAFLEX MB-Plasma system at four light illumination doses: 20, 40, 60, and 120 (standard dose) J/cm(2) . Pre- and posttreatment samples were collected and viral infectivity was determined. The reduction in viral infectivity was calculated for each dose.

RESULTS

Treatment of plasma with the THERAFLEX MB-Plasma system resulted in at least a 4.46-log reduction in all DENV serotypes and CHIKV infectious virus. The residual infectivity for each was at the detection limit of the assay used at 60 J/cm(2) , with dose dependency also observed.

CONCLUSIONS

Our study demonstrated the THERAFLEX MB-Plasma system can reduce the infectivity of all DENV serotypes and CHIKV spiked into plasma to the detection limit of the assay used at half of the standard illumination dose. This suggests this system has the capacity to be an effective option for managing the risk of DENV or CHIKV transfusion transmission in plasma.

A Sensitive and Robust High-Throughput Screening Assay for Inhibitors of the Chikungunya Virus nsP1 Capping Enzyme

Chikungunya virus (CHIKV) is a mosquito-borne Alphavirus that causes severe and debilitating disease symptoms. Alarmingly, transmission rates of CHIKV have increased dramatically over the last decade resulting in 1.7 million suspected cases in the Western hemisphere alone. There are currently no antivirals for treatment of CHIKV infection and novel anti-alphaviral compounds are badly needed. nsP1 is the alphavirus protein responsible for the methyltransferase and guanylyltransferase activities necessary for formation of the 5’ type 0 cap structure added to newly formed viral RNA. Formation of this cap depends on nsP1 binding GTP and transferring a methylated GMP to nascent viral RNA. We have developed a fluorescence polarization-based assay that monitors displacement of a fluorescently-labeled GTP analog in real time. Determining the relative affinities of 15 GTP analogs for nsP1 GTP revealed important structural aspects of GTP that will inform identification of inhibitors able to outcompete GTP for the nsP1 binding site. Validation of the assay for HTS was completed and a secondary orthogonal assay that measures guanylation activity was developed in order to evaluate hits from future drug screens. This platform provides an avenue for identification of potent nsP1 inhibitors, which would potentially provide compounds capable of treating disease caused by CHIKV infection.

High Incidence of Chikungunya Virus and Frequency of Viremic Blood Donations during Epidemic, Puerto Rico, USA, 2014

Deaths were rarely observed, but newborns and other vulnerable populations are at risk for severe complications.

Chikungunya virus (CHIKV) caused large epidemics throughout the Caribbean in 2014. We conducted nucleic acid amplification testing (NAAT) for CHIKV RNA (n = 29,695) and serologic testing for IgG against CHIKV (n = 1,232) in archived blood donor samples collected during and after an epidemic in Puerto Rico in 2014. NAAT yields peaked in October with 2.1% of donations positive for CHIKV RNA. A total of 14% of NAAT-reactive donations posed a high risk for virus transmission by transfusion because of high virus RNA copy numbers (10⁴–10⁹ RNA copies/mL) and a lack of specific IgM and IgG responses. Testing of minipools of 16 donations would not have detected 62.5% of RNA-positive donations detectable by individual donor testing, including individual donations without IgM and IgG. Serosurveys before and after the epidemic demonstrated that nearly 25% of blood donors in Puerto Rico acquired CHIKV infections and seroconverted during the epidemic.

Importance of mosquito "quasispecies" in selecting an epidemic arthropod-borne virus

Most arthropod-borne viruses (arboviruses), perpetuated by alternation between a vertebrate host and an insect vector, are likely to emerge through minor genetic changes enabling the virus to adapt to new hosts. In the past decade, chikungunya virus (CHIKV; Alphavirus, Togaviridae) has emerged on La Réunion Island following the selection of a unique substitution in the CHIKV E1 envelope glycoprotein (E1-A226V) of an East-Central-South African (ECSA) genotype conferring a higher transmission rate by the mosquito Aedes albopictus. Assumed to have occurred independently on at least four separate occasions, this evolutionary convergence was suspected to be responsible for CHIKV worldwide expansion. However, assumptions on CHIKV emergence were mainly based on viral genetic changes and the role of the mosquito population quasispecies remained unexplored. Here we show that the nature of the vector population is pivotal in selecting the epidemic CHIKV. We demonstrate using microsatellites mosquito genotyping that Ae. albopictus populations are genetically differentiated, contributing to explain their differential ability to select the E1-226V mutation. Aedes albopictus, newly introduced in Congo coinciding with the first CHIKV outbreak, was not able to select the substitution E1-A226V nor to preferentially transmit a CHIKV clone harboring the E1-226V as did Ae. albopictus from La Réunion.

Vector competence of Aedes aegypti in transmitting Chikungunya virus: effects and implications of extrinsic incubation temperature on dissemination and infection rates

Background

Aedes aegypti is a competent arthropod vector of chikungunya virus (CHIKV). The rate at which the virus disseminate in the vector is limited by temperature of their environment which can be an important determinant of geographical and seasonal limits to transmission by the arthropods in the tropics. This study investigated the vector competence of Ae. aegypti for CHIKV at ambient temperature of 32 and 26 °C (Coastal and Western Kenya respectively) reared at Extrinsic Incubation Temperature (EIT) of 32 and 26 °C that resembles those in the two regions.

Methods

Ae. aegypti eggs were collected from coastal and Western Kenya, hatched in the insectary and reared to F₁ generation. Four-day old mosquitoes were exposed to CHIKV through a membrane feeding. They were then incubated in temperatures mimicking the mean annual temperatures for Trans-Nzoia (26 °C) and Lamu (32 °C). After every 7, 10 and 13 days post infection (DPI); one third of exposed mosquitoes were sampled and assayed for virus infection and dissemination.

Results

The midgut infection rates (MIR) of Ae. aegypti sampled from Coastal Region was significantly (p < 0.05) higher than those sampled from Western Kenya, with no statistical differences observed for the coastal Ae. aegypti at EIT 26 and at 32 °C. The MIR of Ae. aegypti from the Western Region was significantly (p < 0.05) affected by the EIT, with mosquito reared at EIT 32 °C exhibiting higher MIR than those reared at EIT 26 °C. There was a significant (p < 0.05) interactive effects of the region, EIT and DPI on MIR. The disseminated infection rates for the CHIKV in Ae. aegypti in the legs (DIR-L) was higher in mosquitoes sampled from Coast regardless of the EIT while those from Western Kenya, dissemination rates were significantly higher at higher EIT of 32 °C.

Conclusions

Vector competence was higher in mosquito populations reared under high temperatures which weakens the midgut infection barrier. Hence, suggesting Lamu population is more susceptible to CHIKV therefore having a weaker mid gut infection barrier than the Trans Nzoia population. These underscores importance of examining the course of infection at various ambient temperatures and EIT between regions mosquito populations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-016-0566-7) contains supplementary material, which is available to authorized users.

Neuroinvasion and Inflammation in Viral Central Nervous System Infections

Neurotropic viruses can cause devastating central nervous system (CNS) infections, especially in young children and the elderly. The blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB) have been described as relevant sites of entry for specific viruses as well as for leukocytes, which are recruited during the proinflammatory response in the course of CNS infection. In this review, we illustrate examples of established brain barrier models, in which the specific reaction patterns of different viral families can be analyzed. Furthermore, we highlight the pathogen specific array of cytokines and chemokines involved in immunological responses in viral CNS infections. We discuss in detail the link between specific cytokines and chemokines and leukocyte migration profiles. The thorough understanding of the complex and interrelated inflammatory mechanisms as well as identifying universal mediators promoting CNS inflammation is essential for the development of new diagnostic and treatment strategies.

Activities of proteasome and m-calpain are essential for Chikungunya virus replication

Replication of many viruses is dependent on the ubiquitin proteasome system. The present study demonstrates that Chikungunya virus replication increases proteasome activity and induces unfolded protein response (UPR) in cultured cells. Further, it was seen that the virus replication was dependent on the activities of proteasomes and m-calpain. Proteasome inhibition induced accumulation of polyubiquitinated proteins and earlier visualization of UPR.

Early clearance of Chikungunya virus in children is associated with a strong innate immune response

Chikungunya fever (CHIKF) is a global infectious disease which can affect a wide range of age groups. The pathological and immunological response upon Chikungunya virus (CHIKV) infection have been reported over the last few years. However, the clinical profile and immune response upon CHIKV infection in children remain largely unknown. In this study, we analyzed the clinical and immunological response, focusing on the cytokine/chemokine profile in a CHIKV-infected pediatric cohort from Sarawak, Malaysia. Unique immune mediators triggered upon CHIKV infection were identified through meta-analysis of the immune signatures between this pediatric group and cohorts from previous outbreaks. The data generated from this study revealed that a broad spectrum of cytokines/chemokines is up-regulated in a sub-group of virus-infected children stratified according to their viremic status during hospitalization. Furthermore, different immune mediator profiles (the levels of pro-inflammatory cytokines, chemokines and growth and other factors) were observed between children and adults. This study gives an important insight to understand the immune response of CHIKV infection in children and would aid in the development of better prognostics and clinical management for children.

Chikungunya virus pathogenesis and immunity

Chikungunya virus (CHIKV) is an arbovirus associated with acute and chronic arthralgia that re-emerged in the Indian Ocean islands in 2005-2006 and is currently responsible for the ongoing outbreaks in the Caribbean islands and the Americas. We describe here the acute and chronic clinical manifestations of CHIKV in patients that define the disease. We also review the various animal models that have been developed to study CHIKV infection and pathology and further strengthened the understanding of the cellular and molecular mechanisms of CHIKV infection and immunity. A complete understanding of the immunopathogenesis of CHIKV infection will help develop the needed preventive and therapeutic approaches to combat this arbovirosis.

Vertical transmission of Indian Ocean Lineage of chikungunya virus in Aedes aegypti and Aedes albopictus mosquitoes

Background

The re-emergence of chikungunya (CHIK) fever in Thailand has been caused by a novel lineage of chikungunya virus (CHIKV) termed the Indian Ocean Lineage (IOL). The Aedes albopictus mosquito is thought to be a primary vector of CHIK fever in Thailand, whereas Ae. aegypti acts as a secondary vector of the virus. The vertical transmission is believed to be a primary means to maintain CHIKV in nature and may be associated with an increased risk of outbreak. Therefore, the goal of this study was to analyze the potential of these two Thai mosquito species to transmit the virus vertically and to determine the number of successive mosquito generations for the virus transmission.

Methods

Two-hundred-and-fifty female Ae. aegypti and Ae. albopictus mosquitoes were artificially fed a mixture of human blood and CHIKV IOL. Mosquito larvae and adults were sampled and screened for CHIKV by one-step qRT-PCR. LLC-MK2 cell line was used to isolate CHIKV in the mosquitoes each generation. The virus isolate was identified by immunocytochemical staining and was confirmed by sequencing. Both mosquito species fed on human blood without CHIKV and uninfected LLC-MK2 cells were used as controls.

Results

Aedes aegypti and Ae. albopictus mosquitoes were able to transmit CHIKV vertically to F5 and F6 progenies, respectively. The virus isolated from the two mosquito species caused cytopathic effect in LLC-MK2 cells by 2 days post-infection and immunocytochemical staining showed the reaction between CHIKV IOL antigen and specific monoclonal antibody in the infected cells. DNA sequence confirmed the virus transmitted vertically as CHIKV IOL with E1-A226V mutation. No CHIKV infection was observed in both mosquito species and LLC-MK2 cells from control groups.

Conclusions

The study demonstrated that Ae. aegypti and Ae. albopictus mosquitoes from Thailand are capable of transmitting CHIKV IOL vertically in the laboratory. Our results showed that Ae. albopictus is more susceptible and has a greater ability to transmit the virus vertically than Ae. aegypti. This knowledge would be useful for risk assessments of the maintenance of CHIKV in nature, which is crucial for disease surveillance, vector control and the prevention of potential CHIKV epidemics.

Characterization of N-glycosylation profiles from mammalian and insect cell derived chikungunya VLP

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes severe arthralgia. The envelope of CHIKV is composed of 240 copies of two glycoproteins: E1 and E2. In this work, we have characterized the N-glycosylation patterns of CHIKV virus-like particles (VLPs), containing both E1 and E2 proteins, derived from mammalian and insect cells using hydrophilic interaction liquid chromatography (HILIC) with fluorescence (FL) and mass spectrometry (MS) detection. While HEK293 derived CHIKV VLPs contain oligomannose, hybrid and complex glycans, VLPs derived from SfBasic predominantly contain oligomannose glycans. This strong host dependence of N-glycosylation pattern resembles other alphaviruses such as SINV. The VLPs from HEK293 and SfBasic, with significantly different N-glycosylation profiles, are valuable reagents enabling future in-depth correlation studies between immunogenicity and glycosylation. In addition, the characterization tools presented here allow one to monitor glycosylation during vaccine process development and ensure process consistency.

The Olfactory Bulb: An Immunosensory Effector Organ during Neurotropic Viral Infections

In 1935, the olfactory route was hypothesized to be a portal for virus entry into the central nervous system (CNS). This hypothesis was based on experiments in which nasophayngeal infection with poliovirus in monkeys was prevented from spreading to their CNS via transection of olfactory tracts between the olfactory neuroepithelium (ONE) of the nasal cavity and the olfactory bulb (OB). Since then, numerous neurotropic viruses have been observed to enter the CNS via retrograde transport along axons of olfactory sensory neurons whose cell bodies reside in the ONE. Importantly, this route of infection can occur even after subcutaneous inoculation of arboviruses that can cause encephalitis in humans. While the olfactory route is now accepted as an important pathway for viral entry into the CNS, it is unclear whether it provides a way for infection to spread to other brain regions. More recently, studies of antiviral innate and adaptive immune responses within the olfactory bulb suggest it provides early virologic control. Here we will review the data demonstrating that neurotropic viruses gain access to the CNS initially via the olfactory route with emphasis on findings that suggest the OB is a critical immunosensory effector organ that effectively clears virus.

The Multifactorial Background of Emerging Viral Infections with Neurological Manifestation

The events of the past year have highlighted the continuing importance of emerging virus infections on the diagnosis and treatment of neurological disease. This review focusses on clarifying the effects of the multiple overlapping factors that impact emergence, including viral richness, transmission opportunity, and establishment. Case studies of the West Nile, chikungunya, and Zika viruses are utilised to illustrate the dramatic effects of expansion in the range and geographical distribution of emerging infectious disease, the acquisition of new virus vectors, and of increasing human anthropogenic factors such as global transport, climate change, and mosquito abatement programmes on the regional spread and clinical consequences of emerging infectious disease.

Evaluating the effectiveness of localized control strategies to curtail chikungunya

Chikungunya, a re-emerging arbovirus transmitted to humans by Aedes aegypti and Ae. albopictus mosquitoes, causes debilitating disease characterized by an acute febrile phase and chronic joint pain. Chikungunya has recently spread to the island of St. Martin and subsequently throughout the Americas. The disease is now affecting 42 countries and territories throughout the Americas. While chikungunya is mainly a tropical disease, the recent introduction and subsequent spread of Ae. albopictus into temperate regions has increased the threat of chikungunya outbreaks beyond the tropics. Given that there are currently no vaccines or treatments for chikungunya, vector control remains the primary measure to curtail transmission. To investigate the effectiveness of a containment strategy that combines disease surveillance, localized vector control and transmission reduction measures, we developed a model of chikungunya transmission dynamics within a large residential neighborhood, explicitly accounting for human and mosquito movement. Our findings indicate that prompt targeted vector control efforts combined with measures to reduce transmission from symptomatic cases to mosquitoes may be highly effective approaches for controlling outbreaks of chikungunya, provided that sufficient detection of chikungunya cases can be achieved.

Molecular determinants of alphavirus neuropathogenesis in mice

Alphaviruses are enveloped viruses with a positive-stranded RNA genome, of the family Togaviridae. In mammals and birds they are mosquito-transmitted and are of veterinary and medical importance. They cause primarily two types of disease: encephalitis and polyarthritis. Here we review attempts to understand the molecular basis of encephalitis and virulence for the central nervous system (CNS) in mouse models. Sindbis virus (SINV) was the first virus to be studied in this way. Other viruses analysed are Semliki Forest virus (SFV), Venezuelan equine encephalitis virus, Eastern equine encephalitis virus and Western equine encephalitis virus. Neurovirulence was found to be associated with damage to neurons in the CNS. It mapped mainly to the E2 region of the genome, and to the nsP3 gene. Also, avirulent natural isolates of both SINV and SFV have been found to have more rapid cleavage of nonstructural proteins due to mutations in the nsP1-nsP2 cleavage site. Immune-mediated demyelination for avirulent SFV has been shown to be associated with infection of oligodendrocytes. For Chikungunya virus, an emerging alphavirus that uncommonly causes encephalitis, analysis of the molecular basis of CNS pathogenicity is beginning. Experiments on SINV and SFV have indicated that virulence may be related to the resistance of virulent virus to interferon action. Although the E2 protein may be involved in tropism for neurons and passage across the blood-brain barrier, the role of the nsP3 protein during infection of neurons is unknown. More information in these areas may help to further explain the neurovirulence of alphaviruses.

Phylogenetic analyses of chikungunya virus among travelers in Rio de Janeiro, Brazil, 2014-2015

Chikungunya virus (CHIKV) is a mosquito-borne pathogen that emerged in Brazil by late 2014. In the country, two CHIKV foci characterized by the East/Central/South Africa and Asian genotypes, were established in North and Northeast regions. We characterized, by phylogenetic analyses of full and partial genomes, CHIKV from Rio de Janeiro state (2014-2015). These CHIKV strains belong to the Asian genotype, which is the determinant of the current Northern Brazilian focus, even though the genome sequence presents particular single nucleotide variations. This study provides the first genetic characterisation of CHIKV in Rio de Janeiro and highlights the potential impact of human mobility in the spread of an arthropod-borne virus.

Retrospective seroepidemiological study of chikungunya infection in South Asia, Southeast Asia and the Pacific region

Chikungunya virus (CHIKV) and Ross River virus (RRV) of the genus Alphavirus, family Togaviridae are mainly transmitted by Aedes mosquitoes and the symptoms they cause in patients are similar to dengue. A chikungunya (CHIK) outbreak re-emerged in several Asian countries during 2005-2006. This study aimed to clarify the prevalence of CHIKV infection in suspected dengue patients in six countries in South Asia and Southeast Asia. Seven hundred forty-eight serum samples were from dengue-suspected patients in South Asia and Southeast Asia, and 52 were from patients in Fiji. The samples were analysed by CHIKV IgM capture ELISA, CHIKV IgG indirect ELISA and focus reduction neutralization test against CHIKV or RRV. CHIK-confirmed cases in South Asia, particularly Myanmar and Sri Lanka, were 4·6%, and 6·1%, respectively; and in Southeast Asia, particularly Indonesia, the Philippines and Vietnam, were 27·4%, 26·8% and 25·0%, respectively. It suggests that CHIK was widely spread in these five countries in Asia. In Fiji, no CHIK cases were confirmed; however, RRV-confirmed cases represented 53·6% of suspected dengue cases. It suggests that RRV is being maintained or occasionally entering from neighbouring countries and should be considered when determining a causative agent for dengue-like illness in Fiji.

Diagnostic potential of monoclonal antibodies against the capsid protein of chikungunya virus for detection of recent infection

Chikungunya fever is self-limiting. However, neurological and hemorrhagic complications have been seen in recent outbreaks. The clinical manifestations of this disease are similar to those of dengue virus infection, indicating the need for differential diagnosis in areas such as India, which are endemic for both viruses. The aim of the present study was to develop monoclonal antibodies (MAbs) against Chikungunya virus (CHIKV) and assess their use in MAb-based IgM capture ELISA (MAC ELISA). The ELISA detects CHIKV-specific IgM antibodies, a marker of recent infection, in a patient's serum. One IgG1 and two IgM isotype hybrids were obtained. All of the subclones derived from the IgG1 hybrid recognized the C protein of CHIKV. The anti-C MAb ClVE4/D9 was the most promising as a detector antibody in MAC ELISA (C-MAb ELISA) yielding higher positive-to-negative (P/N) ratios. When compared with the CHIKV MAC ELISA kit developed by the National Institute of Virology (NIV), Pune (NIV MAC ELISA), the sensitivity of the test was 87.01 % with 100 % specificity. The positive and negative predictive values (PPV and NPV) were 100 % and 94.47 %, respectively. In precision testing, standard deviation (SD) and coefficient of variation (% CV) values of the C-MAb ELISA were within acceptable limits. The C-MAb ELISA detected anti-CHIKV IgM in serum of patients up to five months after the onset of infection, indicating that anti-C MAbs have strong potential for use in MAC ELISA to detect recent CHIKV infection.

Preparedness for threat of chikungunya in the pacific

Chikungunya virus (CHIKV) caused significant outbreaks of illness during 2005–2007 in the Indian Ocean region. Chikungunya outbreaks have also occurred in the Pacific region, including in Papua New Guinea in 2012; New Caledonia in April 2013; and Yap State, Federated States of Micronesia, in August 2013. CHIKV is a threat in the Pacific, and the risk for further spread is high, given several similarities between the Pacific and Indian Ocean chikungunya outbreaks. Island health care systems have difficulties coping with high caseloads, which highlights the need for early multidisciplinary preparedness. The Pacific Public Health Surveillance Network has developed several strategies focusing on surveillance, case management, vector control, laboratory confirmation, and communication. The management of this CHIKV threat will likely have broad implications for global public health.

Detection of east/central/south African genotype of chikungunya virus in Myanmar, 2010

In 2010, chikungunya virus of the East Central South African genotype was isolated from 4 children in Myanmyar who had dengue-like symptoms. Phylogenetic analysis of the E1 gene revealed that the isolates were closely related to isolates from China, Thailand, and Malaysia that harbor the A226V mutation in this gene.

Evaluation of Commercially Available Chikungunya Virus Immunoglobulin M Detection Assays

Commercial chikungunya virus (CHIKV)–specific IgM detection kits were evaluated at the Centers for Disease Control and Prevention (CDC), the Public Health Agency of Canada National Microbiology Laboratory, and the Caribbean Public Health Agency (CARPHA). The Euroimmun Anti-CHIKV IgM ELISA kit had ≥ 95% concordance with all three reference laboratory results. The limit of detection for low CHIK IgM+ samples, as measured by serial dilution of seven sera up to 1:12,800 ranged from 1:800 to 1:3,200. The Euroimmun IIFT kit evaluated at CDC and CARPHA performed well, but required more retesting of equivocal results. The InBios CHIKjj Detect MAC-ELISA had 100% and 98% concordance with CDC and CARPHA results, respectively, and had equal sensitivity to the CDC MAC-ELISA to 1:12,800 dilution in serially diluted samples. The Abcam Anti-CHIKV IgM ELISA had high performance at CARPHA, but at CDC, performance was inconsistent between lots. After replacement of the biotinylated IgM antibody controls with serum containing CHIKV-specific IgM and additional quality assurance/control measures, the Abcam kit was rereleased and reevaluated at CDC. The reformatted Abcam kit had 97% concordance with CDC results and limit of detection of 1:800 to 1:3,200. Two rapid tests and three other CHIKV MAC-ELISAs evaluated at CDC had low sensitivity, as the CDC CHIKV IgM in-house positive controls were below the level of detection. In conclusion, laboratories have options for CHIKV serological diagnosis using validated commercial kits.

Imported Chikungunya fever case in Greece in June 2014 and public health response

We report about the first imported case of Chikungunya fever in Greece in a Greek traveler returning from the Dominican Republic and the associated public health response. We investigated the case and performed focused epidemiological and entomological investigation in all areas the patient visited during the infectious period, to identify the targeted interventions needed. Entomological investigation revealed the occurrence of the competent vector Aedes albopictus (Diptera: Culicidae) in the environment surrounding the hospital where the patient was admitted and in her workplace. All captured mosquitoes tested negative for Chikungunya virus. We further conducted clinical and laboratory examination of the patient's co-travelers, gave advice on appropriate personal preventive measures against mosquito bites to the patient and co-travelers and on vector control, and raised awareness among health professionals throughout Greece. The risk of introduction and local transmission of Chikungunya and other arboviruses in Greece and other European countries is present, as the competent vector exists in many parts of Europe. Public health professionals, travel medicine specialists and clinicians should maintain awareness regarding this possibility of importation of arbovirus cases in order to provide the appropriate advice, seek the prompt diagnosis, and implement appropriate interventions. Mobilization of various stakeholders will lead to enhanced epidemiological and entomological surveillance that will allow for improved risk assessment in each area.

Establishment of a Novel Primary Human Skeletal Myoblast Cellular Model for Chikungunya Virus Infection and Pathogenesis

Chikungunya virus (CHIKV) is a re-emerging arbovirus known to cause chronic myalgia and arthralgia and is now considered endemic in countries across Asia and Africa. The tissue tropism of CHIKV infection in humans remains, however, ill-defined. Due to the fact that myositis is commonly observed in most patients infected with CHIKV, we sought to develop a clinically relevant cellular model to better understand the pathogenesis of CHIKV infection. In this study, primary human skeletal muscle myoblasts (HSMM) were established as a novel human primary cell line that is highly permissive to CHIKV infection, with maximal amounts of infectious virions observed at 16 hours post infection. Genome-wide microarray profiling analyses were subsequently performed to identify and map genes that are differentially expressed upon CHIKV infection. Infection of HSMM cells with CHIKV resulted in altered expressions of host genes involved in skeletal- and muscular-associated disorders, innate immune responses, cellular growth and death, host metabolism and virus replication. Together, this study has shown the establishment of a clinically relevant primary human cell model that paves the way for the further analysis of host factors and their involvement in the various stages of CHIKV replication cycle and viral pathogenesis.

Immune Responses to Viruses in the CNS

For recovery from infection, the immune response in the central nervous system (CNS) must eliminate or control virus replication without destroying nonrenewable, essential cells. Thus, upon intracellular virus detection, the infected cell must initiate clearance pathways without triggering neuronal cell death. As a result, the inflammatory response must be tightly regulated and unique mechanisms contribute to the immune response in the CNS. Early restriction of virus replication is accomplished by the innate immune response upon activation of pattern recognition receptors in resident cells. Infiltrating immune cells enter from the periphery to clear virus. Antibodies and interferon-γ are primary contributors to noncytolytic clearance of virus in the CNS. Lymphocytes are retained in the CNS after the acute phase of infection presumably to block reactivation of virus replication.