Determination of Toll-like receptor-induced cytokine profiles in the blood and cerebrospinal fluid of Chikungunya patients

Attenuation of neurovirulence of chikungunya virus by a single amino acid mutation in viral E2 envelope protein

BACKGROUND

Chikungunya virus (CHIKV) has reemerged as a major public health concern, causing chikungunya fever with increasing cases and neurological complications.

METHODS

In the present study, we investigated a low-passage human isolate of the East/ Central/South African (ECSA) lineage of CHIKV strain LK(EH)CH6708, which exhibited a mix of small and large viral plaques. The small and large plaque variants were isolated and designated as CHIKV-SP and CHIKV-BP, respectively. CHIKV-SP and CHIKV-BP were characterized in vitro and in vivo to compare their virus production and virulence. Additionally, whole viral genome analysis and reverse genetics were employed to identify genomic virulence factors.

RESULTS

CHIKV-SP demonstrated lower virus production in mammalian cells and attenuated virulence in a murine model. On the other hand, CHIKV-BP induced higher pro-inflammatory cytokine levels, compromised the integrity of the blood-brain barrier, and led to astrocyte infection in mouse brains. Furthermore, the CHIKV-SP variant had limited transmission potential in Aedes albopictus mosquitoes, likely due to restricted dissemination. Whole viral genome analysis revealed multiple genetic mutations in the CHIKV-SP variant, including a Glycine (G) to Arginine (R) mutation at position 55 in the viral E2 glycoprotein. Reverse genetics experiments confirmed that the E2-G55R mutation alone was sufficient to reduce virus production in vitro and virulence in mice.

CONCLUSIONS

These findings highlight the attenuating effects of the E2-G55R mutation on CHIKV pathogenicity and neurovirulence and emphasize the importance of monitoring this mutation in natural infections.

Innate immune response in patients with acute Chikungunya disease

Chikungunya disease (CHIKD) is an arbovirose that presents with high morbidity, mainly due to arthralgia. Inflammatory mediators including IL-6, IL-1β, GM-CSF and others have been implicated in the pathogenesis of CHIKD, whilst type I interferons can be associated with better outcomes. The role of pattern recognition receptors has been studied incompletely. Here, we evaluated the expression of RNA-specific PRRs, their adaptor molecules and downstream cytokines in acute CHIKD patients. Twenty-eight patients were recruited during the 3rd-5th day after the symptoms onset for clinical examination, peripheral blood collection and qRT-PCR analysis of PBMC to compare to the healthy control group (n = 20). We observed common symptoms of acute CHIKD, with fever, arthralgia, headache and myalgia being the most frequent. Compared with uninfected controls, acute CHIKV infection upregulates the expression of the receptors TLR3, RIG-I and MDA5, and also the adaptor molecule TRIF. Regarding cytokine expression, we found an upregulation of IL-6, IL-12, IFN-α, IFN-β and IFN-γ, which are related directly to the inflammatory or antiviral response. The TLR3-TRIF axis correlated with high expression of IL-6 and IFN-α. Interestingly, greater expression of MDA5, IL-12 and IFN-α was related to lower viral loads in CHIKD acute patients. Together, these findings help to complete the picture of innate immune activation during acute CHIKD, while confirming the induction of strong antiviral responses. Drawing the next steps in the understanding of the immunopathology and virus clearance mechanisms of CHIKD should be of utter importance in the aid of the development of effective treatment to reduce the severity of this debilitating disease.

Chikungunya fever

Chikungunya virus is widespread throughout the tropics, where it causes recurrent outbreaks of chikungunya fever. In recent years, outbreaks have afflicted populations in East and Central Africa, South America and Southeast Asia. The virus is transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Chikungunya fever is characterized by severe arthralgia and myalgia that can persist for years and have considerable detrimental effects on health, quality of life and economic productivity. The effects of climate change as well as increased globalization of commerce and travel have led to growth of the habitat of Aedes mosquitoes. As a result, increasing numbers of people will be at risk of chikungunya fever in the coming years. In the absence of specific antiviral treatments and with vaccines still in development, surveillance and vector control are essential to suppress re-emergence and epidemics.

Parálisis facial aislada posterior a infección por virus de chikunguña: un nuevo diagnóstico diferencial

En las últimas décadas, se ha incrementado el reporte de manifestaciones neurológicas asociadas con la infección por el virus de chikunguña. Se informa el caso de un adulto joven previamente sano que presentó parálisis facial izquierda aislada después de una infección reciente por el virus de chikunguña en el trópico colombiano. Se describen aspectos importantes de la fisiopatología del virus y su tropismo por el sistema nervioso central y periférico, y se sugiere considerar este virus en el diagnóstico diferencial de la parálisis facial en pacientes con infección confirmada por el virus de chikunguña en regiones tropicales endémicas o en aquellos con antecedente de viajes recientes a dichas regiones.

Chikungunya Immunopathology as It Presents in Different Organ Systems

Chikungunya virus (CHIKV) is currently an urgent public health problem as high morbidity from the virus leaves populations with negative physical, social, and economic impacts. CHIKV has the potential to affect every organ of an individual, leaving patients with lifelong impairments which negatively affect their quality of life. In this review, we show the importance of CHIKV in research and public health by demonstrating the immunopathology of CHIKV as it presents in different organ systems. Papers used in this review were found on PubMed, using “chikungunya and [relevant organ system]”. There is a significant inflammatory response during CHIKV infection which affects several organ systems, such as the brain, heart, lungs, kidneys, skin, and joints, and the immune response to CHIKV in each organ system is unique. Whilst there is clinical evidence to suggest that serious complications can occur, there is ultimately a lack of understanding of how CHIKV can affect different organ systems. It is important for clinicians to understand the risks to their patients.

Vitamin D modulates the expression of Toll-like receptors and pro-inflammatory cytokines without affecting Chikungunya virus replication, in monocytes and macrophages

Chikungunya virus (CHIKV) is a zoonotic arthropod-borne virus that causes Chikungunya fever (CHIKF), a self-limiting disease characterized by myalgia and acute or chronic arthralgia. CHIKF pathogenesis has an important immunological component since higher levels of pro-inflammatory factors, including cytokines and chemokines, are detected in CHIKV-infected patients. In vitro studies, using monocytes and macrophages have shown that CHIKV infection promotes elevated production of pro-inflammatory cytokines and antiviral response factors. Vitamin D3 (VD3) has been described as an important modulator of immune response and as an antiviral factor for several viruses. Here, we aimed to study the effects of VD3 treatment on viral replication and pro-inflammatory response in CHIKV-infected human monocytes (VD3-Mon) and monocyte-derived macrophages differentiated in the absence (MDMs) or the presence of VD3 (VD3-MDMs). We found that VD3 treatment did not suppress CHIKV replication in either VD3-Mon or VD3-MDMs. However, the expression of VDR, CAMP and CYP24A1 mRNAs was altered by CHIKV infection. Furthermore, VD3 treatment alters TLRs mRNA expression and production of pro-inflammatory cytokines, including TNFα and CXCL8/IL8, but not IL1β and IL6, in response to CHIKV infection in both VD3-Mon and VD3-MDMs. While a significant decrease in CXCL8/IL8 production was observed in CHIKV-infected VD3-Mon, significantly higher production of CXCL8/IL8 was observed in CHIKV-infected VD3-MDM at 24 hpi. Altogether, our results suggest that vitamin D3 may play an important role in ameliorating pro-inflammatory response during CHIKV infection in human Mon, but not in MDMs. Although further studies are needed to evaluate the efficacy of VD3; nevertheless, this study provides novel insights into its benefits in modulating the inflammatory response elicited by CHIKV infection in humans.

Viral and Prion Infections Associated with Central Nervous System Syndromes in Brazil

Virus-induced infections of the central nervous system (CNS) are among the most serious problems in public health and can be associated with high rates of morbidity and mortality, mainly in low- and middle-income countries, where these manifestations have been neglected. Typically, herpes simplex virus 1 and 2, varicella-zoster, and enterovirus are responsible for a high number of cases in immunocompetent hosts, whereas other herpesviruses (for example, cytomegalovirus) are the most common in immunocompromised individuals. Arboviruses have also been associated with outbreaks with a high burden of neurological disorders, such as the Zika virus epidemic in Brazil. There is a current lack of understanding in Brazil about the most common viruses involved in CNS infections. In this review, we briefly summarize the most recent studies and findings associated with the CNS, in addition to epidemiological data that provide extensive information on the circulation and diversity of the most common neuro-invasive viruses in Brazil. We also highlight important aspects of the prion-associated diseases. This review provides readers with better knowledge of virus-associated CNS infections. A deeper understanding of these infections will support the improvement of the current surveillance strategies to allow the timely monitoring of the emergence/re-emergence of neurotropic viruses.

Immunopathogenesis of alphaviruses

Alphaviruses, members of the enveloped, positive-sense, single-stranded RNA Togaviridae family, represent a reemerging public health threat as mosquito vectors expand into new geographic territories. The Old World alphaviruses, which include chikungunya virus, Ross River virus, and Sindbis virus, tend to cause a clinical syndrome characterized by fever, rash, and arthritis, whereas the New World alphaviruses, which consist of Venezuelan equine encephalitis virus, eastern equine encephalitis virus, and western equine encephalitis virus, induce encephalomyelitis. Following recovery from the acute phase of infection, many patients are left with debilitating persistent joint and neurological complications that can last for years. Clues from human cases and studies using animal models strongly suggest that much of the disease and pathology induced by alphavirus infection, particularly atypical and chronic manifestations, is mediated by the immune system rather than directly by the virus. This review discusses the current understanding of the immunopathogenesis of the arthritogenic and neurotropic alphaviruses accumulated through both natural infection of humans and experimental infection of animals, particularly mice. As treatment following alphavirus infection is currently limited to supportive care, understanding the contribution of the immune system to the disease process is critical to developing safe and effective therapies.

Cytokines and Chemokines in Chikungunya Virus Infection: Protection or Induction of Pathology

Chikungunya virus (CHIKV) infection has been commonly detected in tropical countries. The clinical manifestations of CHIKV infection are similar to those of rheumatoid arthritis. Outbreaks of CHIKV infection in Thailand have been reported, and the inductions of various cytokines and chemokines in CHIKV patients during those outbreaks have been shown. Although immune responses in CHIKV infection have been increasingly reported, the mechanisms associated with pathology induction are still not clearly understood. This review focuses on cytokine and chemokine production in CHIKV infection, in association with the severity of joint inflammation. Several cytokines and chemokines involved in the induction or regulation of inflammatory responses were shown to associate with the severe and persistent symptoms in CHIKV infection. Further studies on the difference in immune responses observed in an autoimmune disease, rheumatoid arthritis, infectious disease, and CHIKV infection, would provide additional insights useful for proper CHIKV therapy, especially in patients with severe joint pains.

Prevalence of chronic chikungunya and associated risks factors in the French West Indies (La Martinique): A prospective cohort study

BACKGROUND

The chikungunya virus (CHIKV) is a re-emerging alphavirus that can cause chronic and potentially incapacitating rheumatic musculoskeletal disorders known as chronic chikungunya arthritis (CCA). We conducted a prospective cohort study of CHIKV-infected subjects during the 2013 chikungunya outbreak in Martinique. The aim of this study was to assess the prevalence of CCA at 12 months and to search for acute phase factors significantly associated with chronicity.

METHODOLOGY/PRINCIPAL FINDINGS

A total of 193 patients who tested positive for CHIKV RNA via qRT-PCR underwent clinical investigations in the acute phase (<21 days), and then 3, 6, and 12 months after inclusion. The Asian lineage was identified as the circulating genotype. A total of 167 participants were classified as either with or without CCA, and were analyzed using logistic regression models. The overall prevalence of CCA at 12 months was 52.1% (95%CI: 44.5-59.7). In univariate analysis, age (RD 9.62, 95% CI, 4.87;14.38, p<0.0001), female sex (RD 15.5, 95% CI, 1.03;30.0, p = 0.04), headache (RD 15.42, 95% CI, 0.65;30.18 p = 0.04), vertigo (RD 15.33, 95% CI, 1.47;29.19, p = 0.03), vomiting (RD 12.89, 95% CI, 1.54;24.24, p = 0.03), dyspnea (RD 13.53, 95% CI, 0.73;26.33, p = 0.04), intravenous rehydration (RD -16.12, 95% CI, -31.58; -0.66 p = 0.04) and urea (RD 0.66, 95% CI, 0.12;1.20, p = 0.02) were significantly associated with the development of CCA. For the subpopulation with data on joint involvement in the acute phase, the risk factors significantly associated with CCA were at least one 1 enthesitis (RD 16.7, 95%CI, 2.8; 30.7, p = 0.02) and at least one tenosynovitis (RD 16.8, 95% CI, 1.4-32.2, p = 0.04).

CONCLUSIONS

This cohort study conducted in Martinique confirms that CCA is a common complication of acute chikungunya disease. Our analysis emphasized the importance of age and female sex for CCA occurrence, and highlighted the aggravating role of dehydration during the acute phase. Early and adequate hydration were found to reduce the risk chronic chikungunya disorders.

TRIAL REGISTRATION

clinicaltrials.gov (NCT01099852).

A scoping review of published literature on chikungunya virus

Chikungunya virus (CHIKV) has caused several major epidemics globally over the last two decades and is quickly expanding into new areas. Although this mosquito-borne disease is self-limiting and is not associated with high mortality, it can lead to severe, chronic and disabling arthritis, thereby posing a heavy burden to healthcare systems. The two main vectors for CHIKV are Aedes aegypti and Aedes albopictus (Asian tiger mosquito); however, many other mosquito species have been described as competent CHIKV vectors in scientific literature. With climate change, globalization and unfettered urban planning affecting many areas, CHIKV poses a significant public health risk to many countries. A scoping review was conducted to collate and categorize all pertinent information gleaned from published scientific literature on a priori defined aspects of CHIKV and its competent vectors. After developing a sensitive and specific search algorithm for the research question, seven databases were searched and data was extracted from 1920 relevant articles. Results show that CHIKV research is reported predominantly in areas after major epidemics have occurred. There has been an upsurge in CHIKV publications since 2011, especially after first reports of CHIKV emergence in the Americas. A list of hosts and vectors that could potentially be involved in the sylvatic and urban transmission cycles of CHIKV has been compiled in this scoping review. In addition, a repository of CHIKV mutations associated with evolutionary fitness and adaptation has been created by compiling and characterizing these genetic variants as reported in scientific literature.

Genetic control of alphavirus pathogenesis

Alphaviruses, members of the positive-sense, single-stranded RNA virus family Togaviridae, represent a re-emerging public health concern worldwide as mosquito vectors expand into new geographic ranges. Members of the alphavirus genus tend to induce clinical disease characterized by rash, arthralgia, and arthritis (chikungunya virus, Ross River virus, and Semliki Forest virus) or encephalomyelitis (eastern equine encephalitis virus, western equine encephalitis virus, and Venezuelan equine encephalitis virus), though some patients who recover from the initial acute illness may develop long-term sequelae, regardless of the specific infecting virus. Studies examining the natural disease course in humans and experimental infection in cell culture and animal models reveal that host genetics play a major role in influencing susceptibility to infection and severity of clinical disease. Genome-wide genetic screens, including loss of function screens, microarrays, RNA-sequencing, and candidate gene studies, have further elucidated the role host genetics play in the response to virus infection, with the immune response being found in particular to majorly influence the outcome. This review describes the current knowledge of the mechanisms by which host genetic factors influence alphavirus pathogenesis and discusses emerging technologies that are poised to increase our understanding of the complex interplay between viral and host genetics on disease susceptibility and clinical outcome.

The neurological complications of chikungunya virus: A systematic review

We performed a systematic review on the neurological complications of chikungunya virus. Such complications are being reported increasingly, owing primarily to the scale of recent epidemics but also to a growing understanding of the virus' neurovirulence. We performed a thorough literature search using PubMed and Scopus databases, summating the data on all published reports of neurological disease associated with chikungunya virus. We appraised the data for each major condition in adults, children, and neonates, as well as evaluating the latest evidence on disease pathogenesis and management strategies. The review provides a comprehensive summary for clinicians, public health officials, and researchers tackling the challenges associated with this important emerging pathogen.

Chikungunya Virus Infection Alters Expression of MicroRNAs Involved in Cellular Proliferation, Immune Response and Apoptosis

OBJECTIVE(S)

Chikungunya virus (CHIKV) is a reemerging virus of significant importance that has caused large-scale outbreaks in the countries with a temperate climate. CHIKV causes debilitating arthralgia which can persist for weeks and up to a year. Fibroblast cells are the main target of CHIKV infection. In this study, we analyzed microRNA (miRNA) modulation in the fibroblast cells infected with CHIKV at an early stage of infection.

METHODS

760 miRNAs were analyzed for modulation following infection with CHIKV at 6 h after infection. Bioinformatic analysis was done to identify the signaling pathway that may be targeted by the significantly modulated miRNAs. Validation of the miRNAs was done using a singleplex miRNA assay and protein target validation of modulated miRNAs was done by Western blot analysis.

RESULTS

Computational analysis of the significantly modulated miRNAs indicated their involvement in signaling pathways such as Toll-like receptor, mTOR, JAK-STAT and Pi3-Akt pathways, which have been shown to play important roles during CHIKV infection. Topoisomerase IIβ, a target of two of the modulated miRNAs, was downregulated upon CHIKV infection.

CONCLUSION(S)

We identified several miRNAs that may play important roles in early events after CHIKV infection and can be potential therapeutic targets against CHIKV infection.

A Systematic Meta-analysis of Immune Signatures in Patients With Acute Chikungunya Virus Infection

BACKGROUND

Individuals infected with chikungunya virus (CHIKV) normally exhibit a variety of clinical manifestations during the acute phase of infection. However, studies in different patient cohorts have revealed that disease manifestations vary in frequency.

METHODS

Disease profiles between patients with acute CHIKV-infection and febrile patients without CHIKV were compared and examined to determine whether any clinical presentations were associated with the clinical outcome of CHIKV infection. Circulatory immune mediators profiles were then characterized and compared with data from 14 independent patient cohort studies. The particular immune mediator signature that defines acute CHIKV infection was determined.

RESULTS

Our findings revealed a specific pattern of clinical presentations of joint-specific arthralgia from this CHIKV cohort. More importantly, we identified an immune mediator signature dominated by proinflammatory cytokines, which include interferon α and γ and interleukin 2, 2R, 6, 7, 12, 15, 17, and 18, across different patient cohorts of CHIKV load associated with arthralgia.

CONCLUSIONS

To our knowledge, this is the first study that associated levels of CHIKV load with arthralgia as an indicator of acute CHIKV infection. Importantly, our findings also revealed specific immune mediator signatures that can be used to better define CHIKV infection.