Chloroquine enhances replication of Semliki Forest virus and encephalomyocarditis virus in mice

Multiple Factors Involved in Bone Damage Caused by Chikungunya Virus Infection

Chronic cases of chikungunya fever represent a public health problem in countries where the virus circulates. The disease is prolonged, in some cases, for years, resulting in disabling pain and bone erosion among other bone and joint problems. As time progresses, tissue damage is persistent, although the virus has not been found in blood or joints. The pathogenesis of these conditions has not been fully explained. Additionally, it has been considered that there are multiple factors that might intervene in the viral pathogenesis of the different conditions that develop. Other mechanisms involved in osteoarthritic diseases of non-viral origin could help explain how damage is produced in chronic conditions. The aim of this review is to analyze the molecular and cellular factors that could be involved in the tissue damage generated by different infectious conditions of the chikungunya virus.

Antivirals and the Potential Benefits of Orally Inhaled Drug Administration in COVID-19 Treatment

Coronavirus Disease 2019 (COVID-19) pandemic has been on the agenda of humanity for more than 2 years. In the meantime, the pandemic has caused economic shutdowns, halt of daily lives and global mobility, overcrowding of the healthcare systems, panic, and worse, more than 6 million deaths. Today, there is still no specific therapy for COVID-19. Research focuses on repurposing of antiviral drugs that are licensed or currently in the research phase, with a known systemic safety profile. However, local safety profile should also be evaluated depending on the new indication, administration route and dosage form. Additionally, various vaccines have been developed. But the causative virus, Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), has undergone multiple variations, too. The premise that vaccines may suffice to eradicate new and all variants is unreliable, as they are based on earlier versions of the virus. Therefore, a specific medication therapy for COVID-19 is crucial and needed in order to prevent severe complications of the disease. Even though there is no specific drug that inhibits the replication of the disease-causing virus, among the current treatment options, systemic antivirals are the most medically appropriate. As SARS-CoV-2 directly targets the lungs and initiates lung damage, treating COVID-19 with inhalants can offer many advantages over the enteral/parenteral administration. Inhaled drug delivery provides higher drug concentration, specifically in the pulmonary system. This enables the reduction of systemic side effects and produces a rapid clinical response. In this article, the most frequently (systemically) used antiviral compounds are reviewed including Remdesivir, Favipiravir, Molnupiravir, Lopinavir-Ritonavir, Umifenovir, Chloroquine, Hydroxychloroquine and Heparin. A comprehensive literature search was conducted to provide insight into the potential inhaled use of these antiviral drugs and the current studies on inhalation therapy for COVID-19 was presented. A brief evaluation was also made on the use of inhaler devices in the treatment of COVID-19. Inhaled antivirals paired with suitable inhaler devices should be considered for COVID-19 treatment options.

G6PD deficiency, redox homeostasis, and viral infections: implications for SARS-CoV-2 (COVID-19)

The COVID-19 pandemic has so far affected more than 45 million people and has caused over 1 million deaths worldwide. Infection with SARS-CoV-2, the pathogenic agent, which is associated with an imbalanced redox status, causes hyperinflammation and a cytokine storm, leading to cell death. Glucose-6-phosphate dehydrogenase (G6PD) deficient individuals may experience a hemolytic crisis after being exposed to oxidants or infection. Individuals with G6PD deficiency are more susceptible to coronavirus infection than individuals with normally functioning G6PD. An altered immune response to viral infections is found in individuals with G6PD deficiency. Evidence indicates that G6PD deficiency is a predisposing factor of COVID-19.

Chloroquine commonly induces hormetic dose responses

The use of chloroquine in the treatment of COVID-19 has received considerable attention. The recent intense focus on this application of chloroquine stimulated an investigation into the effects of chloroquine at low doses on highly biologically-diverse models and whether it may induce hormetic-biphasic dose response effects. The assessment revealed that hormetic effects have been commonly induced by chloroquine, affecting numerous cell types, including tumor cell lines (e.g. human breast and colon) and non-tumor cell lines, enhancing viral replication, sperm motility, various behavioral endpoints as well as decreasing risks of convulsions, and enhancing a spectrum of neuroprotective responses within a preconditioning experimental framework. These diverse and complex findings indicate that hormetic dose responses commonly occur with chloroquine treatment with a range of biological models and endpoints. These findings have implications concerning study design features including the number and spacing of doses, and suggest a range of possible clinical concerns and opportunities depending on the endpoint considered.

Hydroxychloroquine is associated with slower viral clearance in clinical COVID-19 patients with mild to moderate disease

ABSTRACT

There are conflicting data regarding the use of hydroxychloroquine (HCQ) in COVID-19 hospitalized patients. The objective of this study was to assess the efficacy of HCQ in increasing SARS-CoV-2 viral clearance.Hospitalized adult patients with confirmed SARS-CoV-2 infection were retrospectively included in the study. The primary outcome was the time from a confirmed positive nasopharyngeal swab to turn negative. A negative nasopharyngeal swab conversion was defined as a confirmed SARS-CoV-2 case followed by 2 negative results using RT-PCR assay with samples obtained 24 hours apart. Multiple linear regression analysis was used to adjust for potential confounders.Thirty-four confirmed COVID-19 patients completed the study. Nineteen (55.9%) patients presented with symptoms, and 14 (41.2%) had pneumonia. Only 21 (61.8%) patients received HCQ. The time to SARS-CoV-2 negativity nasopharyngeal test was significantly longer in patients who received HCQ than those who did not receive HCQ [17 (13-21) vs 10 (4-13) days, P = .023]. HCQ was independently associated with time to negativity test after adjustment for potential confounders (symptoms, comorbidities, antiviral drugs, pneumonia, or oxygen therapy) in multivariable Cox proportional hazards regression analysis (hazard ratio = 0.33, 95% confidence interval: 0.13-0.9, P = .024). On day 14, 47.8% (14/23) patients tested negative in the HCQ group compared with 90.9% (10/11) patients who did not receive HCQ (P = .016).HCQ was associated with a slower viral clearance in COVID-19 patients with mild to moderate disease. Data from ongoing randomized clinical trials with HCQ should provide a definitive answer regarding the efficacy and safety of this treatment.

Chloroquine and hydroxychloroquine in the treatment of malaria and repurposing in treating COVID-19

Chloroquine (CQ) and Hydroxychloroquine (HCQ) have been commonly used for the treatment and prevention of malaria, and the treatment of autoimmune diseases for several decades. As their new mechanisms of actions are identified in recent years, CQ and HCQ have wider therapeutic applications, one of which is to treat viral infectious diseases. Since the pandemic of the coronavirus disease 2019 (COVID-19), CQ and HCQ have been subjected to a number of in vitro and in vivo tests, and their therapeutic prospects for COVID-19 have been proposed. In this article, the applications and mechanisms of action of CQ and HCQ in their conventional fields of anti-malaria and anti-rheumatism, as well as their repurposing prospects in anti-virus are reviewed. The current trials and future potential of CQ and HCQ in combating COVID-19 are discussed.

Small-Molecule Inhibitors of Chikungunya Virus: Mechanisms of Action and Antiviral Drug Resistance

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that has spread to more than 60 countries worldwide. CHIKV infection leads to a febrile illness known as chikungunya fever (CHIKF), which is characterized by long-lasting and debilitating joint and muscle pain. CHIKV can cause large-scale epidemics with high attack rates, which substantiates the need for development of effective therapeutics suitable for outbreak containment. In this review, we highlight the different strategies used for developing CHIKV small-molecule inhibitors, ranging from high-throughput cell-based screening to in silico screens and enzymatic assays with purified viral proteins.

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that has spread to more than 60 countries worldwide. CHIKV infection leads to a febrile illness known as chikungunya fever (CHIKF), which is characterized by long-lasting and debilitating joint and muscle pain. CHIKV can cause large-scale epidemics with high attack rates, which substantiates the need for development of effective therapeutics suitable for outbreak containment. In this review, we highlight the different strategies used for developing CHIKV small-molecule inhibitors, ranging from high-throughput cell-based screening to in silico screens and enzymatic assays with purified viral proteins. We further discuss the current status of the most promising molecules, including in vitro and in vivo findings. In particular, we focus on describing host and/or viral targets, mode of action, and mechanisms of antiviral drug resistance and associated mutations. Knowledge of the key molecular determinants of drug resistance will aid selection of the most promising antiviral agent(s) for clinical use. For these reasons, we also summarize the available information about drug-resistant phenotypes in Aedes mosquito vectors. From this review, it is evident that more of the active molecules need to be evaluated in preclinical and clinical models to address the current lack of antiviral treatment for CHIKF.

VHSV IVb infection and autophagy modulation in the rainbow trout gill epithelial cell line RTgill-W1

Autophagy modulation influences the success of intracellular pathogens, and an understanding of the mechanisms involved might offer practical options to reduce the impact of infectious disease. Viral haemorrhagic septicaemia virus (VHSV) can cause high mortality and economic loss in some commercial fish species. VHSV IVb was used to infect a rainbow trout gill cell line, RTgill-W1, followed by the treatment of the cells with different autophagy-modulating reagents. LC3II protein using Western blot was significantly (p < .05) decreased for two days following VHSV infection, and immunofluorescence confirmed that LC3II-positive intracytoplasmic puncta were also decreased. Infection with VHSV resulted in significantly decreased expression of the autophagy-related (Atg) genes atg4, at12, atg13 and becn1 after one day using quantitative PCR. Both viral gene copy number and VHSV N protein were significantly decreased by treating the cells with autophagy-blocking (chloroquine) and autophagy-inhibiting reagents (deoxynivalenol and 3-methyladenine) after three days, while autophagy induction (restricted nutrition and rapamycin) had limited effect. Only treatment of RTgill-W1 with deoxynivalenol resulted in a significant increase in expression of type I interferon. Therefore, the suppression of autophagy initially occurs after VHSV IVb infection, but the modulation of autophagy can also inhibit VHSV IVb infection in RTgill-W1 after three days.

Immunomodulatory Effects of Hydroxychloroquine and Chloroquine in Viral Infections and Their Potential Application in Retinal Gene Therapy

Effective treatment of retinal diseases with adeno-associated virus (AAV)-mediated gene therapy is highly dependent on the proportion of successfully transduced cells. However, due to inflammatory reactions at high vector doses, adjunctive treatment may be necessary to enhance the therapeutic outcome. Hydroxychloroquine and chloroquine are anti-malarial drugs that have been successfully used in the treatment of autoimmune diseases. Evidence suggests that at high concentrations, hydroxychloroquine and chloroquine can impact viral infection and replication by increasing endosomal and lysosomal pH. This effect has led to investigations into the potential benefits of these drugs in the treatment of viral infections, including human immunodeficiency virus and severe acute respiratory syndrome coronavirus-2. However, at lower concentrations, hydroxychloroquine and chloroquine appear to exert immunomodulatory effects by inhibiting nucleic acid sensors, including toll-like receptor 9 and cyclic GMP-AMP synthase. This dose-dependent effect on their mechanism of action supports observations of increased viral infections associated with lower drug doses. In this review, we explore the immunomodulatory activity of hydroxychloroquine and chloroquine, their impact on viral infections, and their potential to improve the efficacy and safety of retinal gene therapy by reducing AAV-induced immune responses. The safety and practicalities of delivering hydroxychloroquine into the retina will also be discussed.

Therapeutic use of chloroquine and hydroxychloroquine in COVID-19 and other viral infections: A narrative review

The rapidly spreading Coronavirus Disease (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2), represents an unprecedented serious challenge to the global public health community. The extremely rapid international spread of the disease with significant morbidity and mortality made finding possible therapeutic interventions a global priority. While approved specific antiviral drugs against SARS-CoV-2 are still lacking, a large number of existing drugs are being explored as a possible treatment for COVID-19 infected patients. Recent publications have re-examined the use of Chloroquine (CQ) and/or Hydroxychloroquine (HCQ) as a potential therapeutic option for these patients. In an attempt to explore the evidence that supports their use in COVID-19 patients, we comprehensively reviewed the previous studies which used CQ or HCQ as an antiviral treatment. Both CQ and HCQ demonstrated promising in vitro results, however, such data have not yet been translated into meaningful in vivo studies. While few clinical trials have suggested some beneficial effects of CQ and HCQ in COVID-19 patients, most of the reported data are still preliminary. Given the current uncertainty, it is worth being mindful of the potential risks and strictly rationalise the use of these drugs in COVID-19 patients until further high quality randomized clinical trials are available to clarify their role in the treatment or prevention of COVID-19.

Chloroquine paradox may cause more damage than help fight COVID-19

Novel coronavirus disease 2019 (COVID-19) pandemic is the most recent health care crisis without specific prophylactic or therapeutic drugs. Antimalarial drug chloroquine (CHL) and its safer derivative hydroxychloroquine (HCHL) have been proposed to be repurposed to treat SARS coronavirus-2 (SARS-CoV-2), the causative agent of COVID-19. CHL/HCHL have anti-inflammatory activity and are used to treat rheumatoid arthritis, osteoarthritis and lupus. Although, CHL/HCHL have an anti-viral activity against several viruses in cell-cultures, the anti-viral activity in-vivo is questionable. Repurposing of CHL/HCHL to treat SARS-CoV-2 infection is appealing. However, there is empirical evidence from animal studies with other viruses suggesting that CHL/HCHL may have an untoward paradoxical effect. One thus cannot exclude the possibility that CHL may increase the severity of the disease and prove deleterious both for the patients and public health efforts to contain the highly contagious and explosive spread of SARS-CoV-2.

Of chloroquine and COVID-19

Recent publications have brought attention to the possible benefit of chloroquine, a broadly used antimalarial drug, in the treatment of patients infected by the novel emerged coronavirus (SARS-CoV-2). The scientific community should consider this information in light of previous experiments with chloroquine in the field of antiviral research.

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In vitro data suggest that chloroquine inhibits SARS Cov-2 replication.

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In past research, chloroquine has shown in vitro activity against many different viruses, but no benefit in animal models.

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Chloroquine has been proposed several times for the treatment of acute viral diseases in humans without success.

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The outcomes of some current clinical trials of chloroquine in China have been announced, without access to the data.

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Peer review of the results and an independent assessment of the potential benefit for patients are essential.

Regioselective convergent synthesis of 2-arylidene thiazolo[3,2-a]pyrimidines as potential anti-chikungunya agents

Convergent and convenient regioselective synthesis of novel thiazolo[2,3-a]pyrimidine derivatives was accomplished using the one-pot reaction of 6-ethylthiouracil, bromoacetic acid, anhydrous sodium acetate, acetic anhydride, acetic acid and suitable aldehyde. X-ray crystallographic study reveals the presence of the Z configuration of only one regioisomer confirmed by computational studies as being the most likely isomer present.

Convergent and convenient regioselective synthesis of novel thiazolo[2,3-a]pyrimidines was accomplished using the one-pot reaction of 6-ethylthiouracil, bromoacetic acid, anhydrous sodium acetate, acetic anhydride, acetic acid and suitable aldehyde.

In Vivo Evaluation of Withania somnifera-Based Indian Traditional Formulation ( Amukkara Choornam), Against Chikungunya Virus-Induced Morbidity and Arthralgia

Chikungunya viral fever results in extreme morbidity and arthralgia in affected individuals. Currently, modern medicines providing symptomatic relief for the acute febrile phase and the chronic arthritic phase are only options available. Traditional Indian medical system, however, uses specific formulations for treatment of this infection; one such polyherbal formulation used to treat the postpyretic phase of chikungunya is amukkara choornam. The current study was undertaken to study the efficacy of amukkara choornam in the treatment of chikungunya in C57BL/6J mice. The formulation when administered to chikungunya-infected mice relieved morbidity and joint swelling. Analysis of virus clearance in brain and joint tissues on formulation treatment revealed a direct correlation of viral load in brain to morbidity during infection; likewise, joint swelling receded prior to complete viral clearance explaining possible immunomodulatory effect of amukkara choornam. This study provides insight into the possible mode of action of amukkara choornam during chikungunya.

A compendium of small molecule direct-acting and host-targeting inhibitors as therapies against alphaviruses

Alphaviruses were amongst the first arboviruses to be isolated, characterized and assigned a taxonomic status. They are globally widespread, infecting a large variety of terrestrial animals, birds, insects and even fish. Moreover, they are capable of surviving and circulating in both sylvatic and urban environments, causing considerable human morbidity and mortality. The re-emergence of Chikungunya virus (CHIKV) in almost every part of the world has caused alarm to many health agencies throughout the world. The mosquito vector for this virus, Aedes, is globally distributed in tropical and temperate regions and capable of thriving in both rural and urban landscapes, giving the opportunity for CHIKV to continue expanding into new geographical regions. Despite the importance of alphaviruses as human pathogens, there is currently no targeted antiviral treatment available for alphavirus infection. This mini-review discusses some of the major features in the replication cycle of alphaviruses, highlighting the key viral targets and host components that participate in alphavirus replication and the molecular functions that were used in drug design. Together with describing the importance of these targets, we review the various direct-acting and host-targeting inhibitors, specifically small molecules that have been discovered and developed as potential therapeutics as well as their reported in vitro and in vivo efficacies.

Paradoxical Effect of Chloroquine Treatment in Enhancing Chikungunya Virus Infection

Since 2005, Chikungunya virus (CHIKV) re-emerged and caused numerous outbreaks in the world, and finally, was introduced into the Americas in 2013. The lack of CHIKV-specific therapies has led to the use of non-specific drugs. Chloroquine, which is commonly used to treat febrile illnesses in the tropics, has been shown to inhibit CHIKV replication in vitro. To assess the in vivo effect of chloroquine, two complementary studies were performed: (i) a prophylactic study in a non-human primate model (NHP); and (ii) a curative study "CuraChik", which was performed during the Reunion Island outbreak in 2006 in a human cohort. Clinical, biological, and immunological data were compared between treated and placebo groups. Acute CHIKV infection was exacerbated in NHPs treated with prophylactic administration of chloroquine. These NHPs displayed a higher viremia and slower viral clearance (p < 0.003). Magnitude of viremia was correlated to the type I IFN response (Rho = 0.8, p < 0.001) and severe lymphopenia (Rho = 0.8, p < 0.0001), while treatment led to a delay in both CHIKV-specific cellular and IgM responses (p < 0.02 and p = 0.04, respectively). In humans, chloroquine treatment did not affect viremia or clinical parameters during the acute stage of the disease (D1 to D14), but affected the levels of C-reactive Protein (CRP), IFNα, IL-6, and MCP1 over time (D1 to D16). Importantly, no positive effect could be detected on prevalence of persistent arthralgia at Day 300. Although inhibitory in vitro, chloroquine as a prophylactic treatment in NHPs enhances CHIKV replication and delays cellular and humoral response. In patients, curative chloroquine treatment during the acute phase decreases the levels of key cytokines, and thus may delay adaptive immune responses, as observed in NHPs, without any suppressive effect on peripheral viral load.

Inhibition of chikungunya virus replication by hesperetin and naringenin

Chikungunya virus (CHIKV) is an emerging arbovirus, which has recently become globally important.

Chloroquine enhances replication of influenza A virus A/WSN/33 (H1N1) in dose-, time-, and MOI-dependent manners in human lung epithelial cells A549

Anti-malaria drug, chloroquine, has been reported to be effective against influenza A virus (IAV) in vitro and used in in-vivo experiments and clinical trial for prevention or treatment of influenza. In this study, it has been shown by immunofluorescence, hemagglutination, and plaque assays that chloroquine enhanced A/WSN/33 (H1N1) replication with pronounced cytopathic effect in dose-, time-, and MOI-dependent manners in human lung epithelial cells A549. Time-of-addition assay showed that inhibitory effect on virus replication by chloroquine pre-treatment was indistinctive, and virus productions were enhanced when the drug was applied after viral adsorption. The effectiveness of chloroquine as an anti-influenza drug is questioned, and caution in its use is recommended.

Antiviral perspectives for chikungunya virus

Chikungunya virus (CHIKV) is a mosquito-borne pathogen that has a major health impact in humans and causes acute febrile illness in humans accompanied by joint pains and, in many cases, persistent arthralgia lasting for weeks to years. CHIKV reemerged in 2005-2006 in several parts of the Indian Ocean islands and India after a gap of 32 years, causing millions of cases. The re-emergence of CHIKV has also resulted in numerous outbreaks in several countries in the eastern hemisphere, with a threat to further expand in the near future. However, there is no vaccine against CHIKV infection licensed for human use, and therapy for CHIKV infection is still mainly limited to supportive care as antiviral agents are yet in different stages of testing or development. In this review we explore the different perspectives for chikungunya treatment and the effectiveness of these treatment regimens and discuss the scope for future directions.

Approaches to the treatment of disease induced by chikungunya virus

Chikungunya virus, a re-emerging mosquito-borne alphavirus, causes fever, rash and persistent arthralgia/arthritis in humans. Severe outbreaks have occurred resulting in infections of millions of people in Southeast Asia and Africa. Currently there are no antiviral drugs or vaccines for prevention and treatment of chikungunya infections. Herein we report the current status of research on antiviral drugs and vaccines for chikungunya virus infections.

Chikungunya virus: emerging targets and new opportunities for medicinal chemistry

Chikungunya virus is an emerging arbovirus that is widespread in tropical regions and is spreading quickly to temperate climates with recent epidemics in Africa and Asia and documented outbreaks in Europe and the Americas. It is having an increasingly major impact on humankind, with potentially life-threatening and debilitating arthritis. There is no treatment available, and only in the past 24 months have lead compounds for development as potential therapeutics been reported. This Perspective discusses the chikungunya virus as a significant, new emerging topic for medicinal chemistry, highlighting the key viral target proteins and their molecular functions that can be used in drug design, as well as the most important ongoing developments for anti-chikungunya virus research. It represents a complete picture of the current medicinal chemistry of chikungunya, supporting the development of chemotherapeutics through drug discovery and design targeting this virus.

Chikungunya fever: epidemiology, clinical syndrome, pathogenesis and therapy

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Chikungunya fever is caused by a mosquito-borne alphavirus originating in East Africa.

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During the past 7 years, the disease has spread to islands of the Indian Ocean, Asia and Europe.

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Its spread has been facilitated by a mutation favouring replication in the mosquito Ae. albopictus.

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No vaccines or antiviral drugs are available to prevent or treat chikungunya fever.

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This paper provides an extensive review of the virus and disease, including Supplementary Tables.

Chikungunya virus (CHIKV) is the aetiological agent of the mosquito-borne disease chikungunya fever, a debilitating arthritic disease that, during the past 7 years, has caused immeasurable morbidity and some mortality in humans, including newborn babies, following its emergence and dispersal out of Africa to the Indian Ocean islands and Asia. Since the first reports of its existence in Africa in the 1950s, more than 1500 scientific publications on the different aspects of the disease and its causative agent have been produced. Analysis of these publications shows that, following a number of studies in the 1960s and 1970s, and in the absence of autochthonous cases in developed countries, the interest of the scientific community remained low. However, in 2005 chikungunya fever unexpectedly re-emerged in the form of devastating epidemics in and around the Indian Ocean. These outbreaks were associated with mutations in the viral genome that facilitated the replication of the virus in Aedes albopictus mosquitoes. Since then, nearly 1000 publications on chikungunya fever have been referenced in the PubMed database. This article provides a comprehensive review of chikungunya fever and CHIKV, including clinical data, epidemiological reports, therapeutic aspects and data relating to animal models for in vivo laboratory studies. It includes Supplementary Tables of all WHO outbreak bulletins, ProMED Mail alerts, viral sequences available on GenBank, and PubMed reports of clinical cases and seroprevalence studies.

Emergence and clinical insights into the pathology of Chikungunya virus infection

Major epidemics of Chikungunya have re-emerged with millions of cases worldwide. What was once largely a tropical disease in poorer countries is now recognized as a major global health issue. The disease is perpetuated by the alphavirus Chikungunya, and is transmitted by Aedes mosquitoes. The infection is highly symptomatic, with fever, skin rash and incapacitating arthralgia, which can evolve to chronic arthritis and rheumatism in elderly patients. Mother-to-child transmission, encephalitis, Guillain-Barré syndrome and deaths have been noted. In this article, we will highlight the epidemiological, clinical, virological and immunological aspects of the disease and mention the therapies that have been used during recent epidemics. Novel prevention measures to control the mosquito and a new vaccine are highly warranted.

Chloroquine and its derivatives exacerbate B19V-associated anemia by promoting viral replication

Background

An unexpectedly high seroprevalence and pathogenic potential of human parvovirus B19 (B19V) have been observed in certain malaria-endemic countries in parallel with local use of chloroquine (CQ) as first-line treatment for malaria. The aims of this study were to assess the effect of CQ and other common antimalarial drugs on B19V infection in vitro and the possible epidemiological consequences for children from Papua New Guinea (PNG).

Methodology/Principal Findings

Viral RNA, DNA and proteins were analyzed in different cell types following infection with B19V in the presence of a range of antimalarial drugs. Relationships between B19V infection status, prior 4-aminoquinoline use and anemia were assessed in 200 PNG children <10 years of age participating in a case-control study of severe infections. In CQ-treated cells, the synthesis of viral RNA, DNA and proteins was significantly higher and occurred earlier than in control cells. CQ facilitates B19V infection by minimizing intracellular degradation of incoming particles. Only amodiaquine amongst other antimalarial drugs had a similar effect. B19V IgM seropositivity was more frequent in 111 children with severe anemia (hemoglobin <50 g/L) than in 89 healthy controls (15.3% vs 3.4%; P = 0.008). In children who were either B19V IgM or PCR positive, 4-aminoquinoline use was associated with a significantly lower admission hemoglobin concentration.

Conclusions/Significance

Our data strongly suggest that 4-aminoquinoline drugs and their metabolites exacerbate B19V-associated anemia by promoting B19V replication. Consideration should be given for choosing a non-4-aminoquinoline drug to partner artemisinin compounds in combination antimalarial therapy.

Human parvovirus B19 (B19V) is typically associated with a childhood febrile illness known as erythema infectiosum. The infection usually resolves without consequence in healthy individuals. However, in patients with immunologic and/or hematologic disorders, B19V can cause a significant pathology. The virus infects and kills red cell precursors but anemia rarely supervenes unless there is pre-existing anemia such as in children living in malaria-endemic regions. The link between B19V infection and severe anemia has, however, only been confirmed in certain malaria-endemic countries in parallel with chloroquine (CQ) usage. This raises the possibility that CQ may increase the risk of severe anemia by promoting B19V infection. To test this hypothesis, we examined the direct effect of CQ and other commonly used antimalarial drugs on B19V infection in cultured cell lines. Additionally, we examined the correlation between B19V infection, hemoglobin levels and use of CQ in children from Papua New Guinea hospitalized with severe anemia. The results suggest strongly that CQ and its derivatives aggravate B19V-associated anemia by promoting B19V replication. Hence, careful consideration should be given in choosing the drug partnering artemisinin compounds in combination antimalarial therapy in order to minimize contribution of B19V to severe anemia.

Understanding the alphaviruses: recent research on important emerging pathogens and progress towards their control

The alphaviruses were amongst the first arboviruses to be isolated, characterized and assigned a taxonomic status. They are globally very widespread, infecting a large variety of terrestrial animals, insects and even fish, and circulate both in the sylvatic and urban/peri-urban environment, causing considerable human morbidity and mortality. Nevertheless, despite their obvious importance as pathogens, there are currently no effective antiviral drugs with which to treat humans or animals infected by any of these viruses. The EU-supported project-VIZIER (Comparative Structural Genomics of Viral Enzymes Involved in Replication, FP6 PROJECT: 2004-511960) was instigated with an ultimate view of contributing to the development of antiviral therapies for RNA viruses, including the alphaviruses [Coutard, B., Gorbalenya, A.E., Snijder, E.J., Leontovich, A.M., Poupon, A., De Lamballerie, X., Charrel, R., Gould, E.A., Gunther, S., Norder, H., Klempa, B., Bourhy, H., Rohayemj, J., L'hermite, E., Nordlund, P., Stuart, D.I., Owens, R.J., Grimes, J.M., Tuckerm, P.A., Bolognesi, M., Mattevi, A., Coll, M., Jones, T.A., Aqvist, J., Unger, T., Hilgenfeld, R., Bricogne, G., Neyts, J., La Colla, P., Puerstinger, G., Gonzalez, J.P., Leroy, E., Cambillau, C., Romette, J.L., Canard, B., 2008. The VIZIER project: preparedness against pathogenic RNA viruses. Antiviral Res. 78, 37-46]. This review highlights some of the major features of alphaviruses that have been investigated during recent years. After describing their classification, epidemiology and evolutionary history and the expanding geographic distribution of Chikungunya virus, we review progress in understanding the structure and function of alphavirus replicative enzymes achieved under the VIZIER programme and the development of new disease control strategies.

On chikungunya acute infection and chloroquine treatment

In recent issues, the efficacy of chloroquine (and the dosage that may be used) in the treatment of acute chikungunya infections was discussed. We have conducted a double-blind placebo-controlled randomized trial on the French Reunion Island (Indian Ocean), in which 27 patients received chloroquine and 27 patients received a placebo treatment. The chloroquine treatment consisted of 600 mg at day 1, 600 mg at days 2 and 3, and 300 mg at days 4 and 5. No significant difference between groups could be identified regarding the duration of febrile arthralgia or the decrease of viremia between day 1 and day 3. However, at day 200, patients who received chloroquine complained more frequently of arthralgia than those who received placebo (p < 0.01). In conclusion, our results suggest that there is currently no justification for the use of chloroquine to treat acute chikungunya infections.

Optimization of adenoviral production in human embryonic kidney cells using response surface methodology

Adenoviruses are the most commonly used vectors in clinical trials for gene therapy. How to efficiently produce abundant and high-quality adenoviral vectors for therapeutic research is a challenge for biochemical engineers. A recombinant adenovirus carrying a green fluorescent protein (GFP) gene together with an anchorage-dependent 293 cell line is used as a model system for evaluating the effects of chemicals on adenoviral production in this study. Our aim is to develop a formulation to be added to an infection medium that could enhance the in vitro production of adenoviral vectors. Eleven ingredients obtained from a literature survey were screened for their stimulatory effects on adenoviral production using the 50% tissue culture infectious dose (TCID(50)) method. Among these ingredients, sucrose and mannitol when supplemented to the infection medium significantly increased adenovirus titer. Central composite design and response surface methodology were also adopted to determine the optimal concentrations of sucrose and mannitol. The formulation developed, which is composed of DMEM/F12 medium plus 0.54 M sucrose and 0.37 M mannitol, can significantly increase adenoviral production by 13-fold that of the control (DMEM/F12 medium).

The pathway of feline calicivirus entry

The requirement for a low pH-dependent step during feline calicivirus (FCV) entry into Crandell-Reese feline kidney cells was investigated. Chloroquine, a lysosomotropic agent that prevents acidification of intracellular vesicles, inhibited the production of infectious virus when present during adsorption and the initial stages of FCV replication, but had little effect when added after 2 h post infection. The effect of chloroquine was reversible, allowing the virus growth curve to proceed when removed from the culture. In the presence of chloroquine small amounts of viral RNA were detected at 4, 6, and 8 h post infection, compared to untreated infected cells. These results suggest that entry of feline calicivirus into cells requires a low pH-dependent step.

Chloroquine induces empty capsid formation during poliovirus eclipse

The poliovirus capsid (160S) is modified during eclipse in HeLa cells, which results in at least three types of particles having sedimentation coefficients of 135, 110, and 80S. The lysosomotropic agent chloroquine redirected the production of eclipse products from 135 and 110S particles (containing RNA) to 80S particles (without RNA). The effect started at 5 microM and was fully developed with 20 microM chloroquine. Viral protein synthesis and virion production remained unaffected. The results show that chloroquine can redirect the processing of input virions without interfering with productive uncoating.