Tropical arthritogenic alphaviruses. / Alfavirus tropicales artritogénicos.

Tropical alphaviruses have special tropism for bone and joint tissue. Patients can develop chronic rheumatic disorders similar to rheumatoid arthritis and ankylosing spondylitis. The prototype is Chikungunya virus, although other lesser known viruses in our environment such as Sindbis, Ross River, Mayaro, O'nyong nyong and Barmah Forest viruses have the potential to be sped through vectors and cause chronic rheumatic disease. International population movements have increased the numbers of patients diagnosed with these tropical viruses in areas in which they are not endemic. Since they can leave persistent symptoms and affect the quality of life of the patients, it is important that we be aware of them. Changes in ecosystems have favored the expansion of competent mosquitoes, making fears of local transmission in southern Europe a reality. The objective of this review is to provide a clinical approach to the different arthritogenic tropical alphaviruses, especially those in which chronic rheumatic disease is more frequent.

Ross River virus disease clinical presentation, pathogenesis and current therapeutic strategies.

Ross River virus (RRV) is an arthitogenic alphavirus capable of causing outbreaks of debilitating musculoskeletal inflammatory disease in humans. RRV is the most common mosquito-borne disease in Australia, with outbreaks of RRV generally occurring during seasonal wet and warm conditions. Patients with Ross River virus disease (RRVD) typically present with fever, polyarthralgia, myalgia and a maculopapular erythematous rash. Treatment of the disease is usually palliative with no licensed vaccines or antiviral therapies currently available. In an effort to better inform therapeutic design, much progress has been made to understand the pathogenesis of RRVD. Progress has been largely driven by clinical evaluations supported by research using established murine models of RRVD, able to accurately replicate human disease. In this review we describe RRVD pathogenesis and the role of the host immune response, with particular focus on insights from studying animal models. We also discuss prospects for effective vaccines, preclinical development of therapeutic strategies and raise important questions for future RRV research.

Broadly Neutralizing Alphavirus Antibodies Bind an Epitope on E2 and Inhibit Entry and Egress.

We screened a panel of mouse and human monoclonal antibodies (MAbs) against chikungunya virus and identified several with inhibitory activity against multiple alphaviruses. Passive transfer of broadly neutralizing MAbs protected mice against infection by chikungunya, Mayaro, and O'nyong'nyong alphaviruses. Using alanine-scanning mutagenesis, loss-of-function recombinant proteins and viruses, and multiple functional assays, we determined that broadly neutralizing MAbs block multiple steps in the viral lifecycle, including entry and egress, and bind to a conserved epitope on the B domain of the E2 glycoprotein. A 16 Å resolution cryo-electron microscopy structure of a Fab fragment bound to CHIKV E2 B domain provided an explanation for its neutralizing activity. Binding to the B domain was associated with repositioning of the A domain of E2 that enabled cross-linking of neighboring spikes. Our results suggest that B domain antigenic determinants could be targeted for vaccine or antibody therapeutic development against multiple alphaviruses of global concern.

Chikungunya viruses that escape monoclonal antibody therapy are clinically attenuated, stable, and not purified in mosquitoes.

UNLABELLED: Chikungunya virus (CHIKV) is a reemerging mosquito-transmitted alphavirus that causes epidemics of debilitating polyarthritis in humans. A prior study identified two anti-CHIKV monoclonal antibodies ([MAbs] CHK-152 and CHK-166) against the E2 and E1 structural proteins, which had therapeutic efficacy in immunocompetent and immunocompromised mice. Combination MAb therapy was required as administration of a single MAb resulted in the rapid selection of neutralization escape variants and treatment failure in mice. Here, we initially evaluated the efficacy of combination MAb therapy in a nonhuman primate model of CHIKV infection. Treatment of rhesus macaques with CHK-152 and CHK-166 reduced viral spread and infection in distant tissue sites and also neutralized reservoirs of infectious virus. Escape viruses were not detected in the residual viral RNA present in tissues and organs of rhesus macaques. To evaluate the possible significance of MAb resistance, we engineered neutralization escape variant viruses (E1-K61T, E2-D59N, and the double mutant E1-K61T E2-D59N) that conferred resistance to CHK-152 and CHK-166 and tested them for fitness in mosquito cells, mammalian cells, mice, and Aedes albopictus mosquitoes. In both cell culture and mosquitoes, the mutant viruses grew equivalently and did not revert to wild-type (WT) sequence. All escape variants showed evidence of mild clinical attenuation, with decreased musculoskeletal disease at early times after infection in WT mice and a prolonged survival time in immunocompromised Ifnar1(-/-) mice. Unexpectedly, this was not associated with decreased infectivity, and consensus sequencing from tissues revealed no evidence of reversion or compensatory mutations. Competition studies with CHIKV WT also revealed no fitness compromise of the double mutant (E1-K61T E2-D59N) neutralization escape variant in WT mice. Collectively, our study suggests that neutralization escape viruses selected during combination MAb therapy with CHK-152 plus CHK-166 retain fitness, cause less severe clinical disease, and likely would not be purified during the enzootic cycle. IMPORTANCE: Chikungunya virus (CHIKV) causes explosive epidemics of acute and chronic arthritis in humans in Africa, the Indian subcontinent, and Southeast Asia and recently has spread to the New World. As there are no approved vaccines or therapies for human use, the possibility of CHIKV-induced debilitating disease is high in many parts of the world. To this end, our laboratory recently generated a combination monoclonal antibody therapy that aborted lethal and arthritogenic disease in wild-type and immunocompromised mice when administered as a single dose several days after infection. In this study, we show the efficacy of the antibody combination in nonhuman primates and also evaluate the significance of possible neutralization escape mutations in mosquito and mammalian cells, mice, and Aedes albopictus vector mosquitoes. Our experiments show that escape viruses from combination antibody therapy cause less severe CHIKV clinical disease, retain fitness, and likely would not be purified by mosquito vectors.

Administration of E2 and NS1 siRNAs inhibit chikungunya virus replication in vitro and protects mice infected with the virus.

BACKGROUND: Chikungunya virus (CHIKV) has reemerged as a life threatening pathogen and caused large epidemics in several countries. So far, no licensed vaccine or effective antivirals are available and the treatment remains symptomatic. In this context, development of effective and safe prophylactics and therapeutics assumes priority. METHODS: We evaluated the efficacy of the siRNAs against ns1 and E2 genes of CHIKV both in vitro and in vivo. Four siRNAs each, targeting the E2 (Chik-1 to Chik-4) and ns1 (Chik-5 to Chik-8) genes were designed and evaluated for efficiency in inhibiting CHIKV growth in vitro and in vivo. Chik-1 and Chik-5 siRNAs were effective in controlling CHIKV replication in vitro as assessed by real time PCR, IFA and plaque assay. CONCLUSIONS: CHIKV replication was completely inhibited in the virus-infected mice when administered 72 hours post infection. The combination of Chik-1 and Chik-5 siRNAs exhibited additive effect leading to early and complete inhibition of virus replication. These findings suggest that RNAi capable of inhibiting CHIKV growth might constitute a new therapeutic strategy for controlling CHIKV infection and transmission.

[The tropical disease Chikungunya fever has come to Europe]. / Tropesygdommen chikungunya-feber er kommet til Europa.

Chikungunya fever is an acute febrile illness associated with severe, often debilitating polyarthralgias. The disease is caused by the Chikungunya virus (CHIKV), an arthropod-borne virus that is transmitted to humans primarily via the bite of an infected mosquito. Since a re-emergence of CHIKV in 2004 in the Indian Ocean islands, the virus has spread into novel locations such as Europe. In Italy, an outbreak occurred in 2007. A mutation in CHIKV (E1-A226V) appears to improve virus survival in Ae. albopictus and also increase its virulence. Further attention should be given the disease since it is emerging in Europe.

[Feedback from primary care practitioners two years after the chikungunya epidemic on Reunion Island, 2005-2006]. / Retour d'expérience des médecins généralistes deux ans après l'épidémie de chikungunya de 2005-2006 à La Réunion.

Primary care practitioners constitute key stakeholders in the surveillance and control of epidemic-prone infectious diseases. We carried out a survey in Reunion Island two years after the 2006 chikungunya epidemic using a purposive random sample of 100 general practitioners (GP). The objective was to describe and identity factors associated to GP involvement in case notification during the 2006 chikungunya epidemic. The methods were: administered face-to-face questionnaire and identification of notification determinants by univariate and multivariate analyses. Nearly 60% of participants declared having failed to join the case notification procedure. The main impeding factor was the acknowledgment of limited capacities consecutive to massive influx of patients. Inversely, practicing in group organization tended to show a favorable effect on case notification. In addition, most responders reported the relevance of the information provided by health authorities, despite a perceived limited efficacy of the procedure in the field. Primary care practitioners' involvement in the surveillance of epidemic infectious diseases requires to be reinforced by a preestablished partnership within a proactive network. This goal comprehends relevant training and preparation for epidemic surveillance.

Development of a highly protective combination monoclonal antibody therapy against Chikungunya virus.

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that causes global epidemics of a debilitating polyarthritis in humans. As there is a pressing need for the development of therapeutic agents, we screened 230 new mouse anti-CHIKV monoclonal antibodies (MAbs) for their ability to inhibit infection of all three CHIKV genotypes. Four of 36 neutralizing MAbs (CHK-102, CHK-152, CHK-166, and CHK-263) provided complete protection against lethality as prophylaxis in highly susceptible immunocompromised mice lacking the type I IFN receptor (Ifnar(-/-) ) and mapped to distinct epitopes on the E1 and E2 structural proteins. CHK-152, the most protective MAb, was humanized, shown to block viral fusion, and require Fc effector function for optimal activity in vivo. In post-exposure therapeutic trials, administration of a single dose of a combination of two neutralizing MAbs (CHK-102+CHK-152 or CHK-166+CHK-152) limited the development of resistance and protected immunocompromised mice against disease when given 24 to 36 hours before CHIKV-induced death. Selected pairs of highly neutralizing MAbs may be a promising treatment option for CHIKV in humans.

Photochemical inactivation of chikungunya virus in human apheresis platelet components by amotosalen and UVA light.

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that recently re-emerged in Africa and rapidly spread into countries of the Indian Ocean basin and South-East Asia. The mean viremic blood donation risk for CHIKV on La Réunion reached 1.5% at the height of the 2005-2006 outbreaks, highlighting the need for development of safety measures to prevent transfusion-transmitted infections. We describe successful inactivation of CHIKV in human platelets and plasma using photochemical treatment with amotosalen and long wavelength UVA illumination. Platelet components in additive solution and plasma units were inoculated with two different strains of high titer CHIKV stock (6.0-8.0 logs/mL), and then treated with amotosalen and exposure to 1.0-3.0 J/cm² UVA. Based on in vitro assays of infectious virus pre- and post-treatment to identify endpoint dilutions where virus was not detectable, mean viral titers could effectively be reduced by > 6.4 ± 0.6 log10 TCID50/mL in platelets and ≥ 7.6 ± 1.4 logs in plasma, indicating this treatment has the capacity to prevent CHIKV transmission in human blood components collected from infected donors in or traveling from areas of CHIKV transmission.

Use of human monoclonal antibodies to treat Chikungunya virus infection.

Chikungunya virus (CHIKV) is an alphavirus prevalent in tropical regions. It causes an acute febrile disease that, in elderly individuals and newborns, is often associated with severe complications. We previously reported the isolation and characterization of 2 human monoclonal antibodies neutralizing CHIKV in vitro: 5F10 and 8B10. Here, we tested their efficacy in vivo as prophylactic and therapeutic treatments of CHIKV infection in AGR129 mice. In both settings, 5F10 and 8B10 were able to significantly delay CHIKV-driven lethality. Our results support the development of prophylactic and therapeutic treatments for CHIKV infection, using a combination of 5F10 and 8B10.

Genetic ablation of arginase 1 in macrophages and neutrophils enhances clearance of an arthritogenic alphavirus.

Chikungunya virus (CHIKV) and Ross River virus (RRV) cause a debilitating, and often chronic, musculoskeletal inflammatory disease in humans. Macrophages constitute the major inflammatory infiltrates in musculoskeletal tissues during these infections. However, the precise macrophage effector functions that affect the pathogenesis of arthritogenic alphaviruses have not been defined. We hypothesized that the severe damage to musculoskeletal tissues observed in RRV- or CHIKV-infected mice would promote a wound-healing response characterized by M2-like macrophages. Indeed, we found that RRV- and CHIKV-induced musculoskeletal inflammatory lesions, and macrophages present in these lesions, have a unique gene-expression pattern characterized by high expression of arginase 1 and Ym1/Chi3l3 in the absence of FIZZ1/Relmα that is consistent with an M2-like activation phenotype. Strikingly, mice specifically deleted for arginase 1 in neutrophils and macrophages had dramatically reduced viral loads and improved pathology in musculoskeletal tissues at late times post-RRV infection. These findings indicate that arthritogenic alphavirus infection drives a unique myeloid cell activation program in inflamed musculoskeletal tissues that inhibits virus clearance and impedes disease resolution in an arginase 1-dependent manner.

[The messenger syndrome]. / Le syndrome du messager.

Since mid 2005 pediatricians of the Groupe hospitalier Sud Reunion de Saint-Pierre have observed a self-imposed requirement to test for mother-to-child transmission of chikungunya. Sanitary authorities refuse to consider such testing as necessary. The risk of mother-to-child transmission was not mentioned in literature of the time.

["Emergency measures"]. / "Les mesures d'urgence".

This article deals with the impact of health crisis on governance of public health. It tries to show that, in accordance with the thought of Michel Foucault, emergency measures issued during health crisis are akin to those issued during wartime.

[Critical analysis of requirements for scientific assessment as a basis for good governance: case of the chikungunya epidemic on Reunion Island and Mayotte in 2005 and 2006]. / L'analyse critique du respect des conditions de bonne gouvernance en matière d'evaluation scientifique des risques: le cas de l'epidémie de chikungunya a La Réunion et a Mayotte en 2005 et 2006.

The constitutional precautionary principle as applied in laws governing health care at the community level requires rigorous scientific assessment. The goal of this assessment is to provide authorities with sound evidence as a basis for implementing precautionary measures in function of degree of risk and other parameters such as the level of public health protection that is high in the EU. As the political authority, the government can act independently of conclusions issued by scientific commissions provided that the commission's level of expertise meets national and European standards and that research methodology and findings are consistent with scientific data published in the international literature. These requirements were not meet for the chikungunya pandemic that struck France on Reunion Island and Mayotte from 2004 to 2006. This epidemic that was preceded by many outbreaks in Indonesia between 2001 and 2003 began in Africa and then swept across the Indian Ocean to India and Asia. After an overview of the scientific assessment, this article raises arguments supporting possible allegations of gross misgovernance by the state and experts.

[Chikungunya on Reunion Island. Experience, opinion, and proposals of general practitioners: poorly understood symptoms, lack of treatment protocol, exaggerated sequels, neglected players]. / Chikungunya a la Réunion. une symptomatologie mal connue, un traitement a découvrir, des séquelles exagérées, des acteurs négligés: les médecins de terrain constatent, s'expriment et proposent....

In 2005-2006 the Chikungunya caused a major sanitary crisis in Reunion for which neither the authorities, nor the healthcare professionals were prepared, as the symptoms were poorly defined, the treatment not validated and the sequels underestimated. General practioners described "in vivo" clinical and therapeutic facts and help conducted three ground studies. They were indeed the doctors of first recourse for painful and feverish patients. Have we drawn all lessons of this sanitary crisis that struck nearly the third of the population? Are we better prepared to face the acute and the chronic forms of a forthcoming epidemic? Efforts and indisputable institutional progress were made, but "Everything" still remains to be made combining all health professional efforts with a better consideration of the professionals of ground.

[Severe forms of chikungunya virus infection in a pediatric intensive care unit on Reunion Island]. / Infections graves a virus chikungunya en réanimation pédiatrique a l'ile de La Réunion.

UNLABELLED: In 2005-2006, an unexpected, massive outbreak of chikungunya occurred on Reunion Island, a French overseas territory in the Indian Ocean. This arboviral infection transmitted by a mosquito of the Aedes genus is usually benign. A surprising feature of the Reunion Island epidemic was the occurrence of rare severe forms involving adults as well as children. OBJECTIVES: The purpose of this report is to describe severe forms of chikungunya observed in children hospitalized in a pediatric intensive care unit. PATIENTS AND METHODS: This retrospective single-center study was conducted from January 1st to April 30th, 2006. Children between 1 month and 15 years admitted to the pediatric intensive care unit with proven chikungunya infection were included. RESULTS: A total of 9 children were included. The main manifestations were extensive skin blisters in 5 cases, neurological symptoms (encephalopathy) in 4, cardiac complications (myocarditis, hemodynamic disorders) in 5 and bleeding in 1. Two children died. The causes of death were circulatory failure associated with coma and massive hemorrhage in one case and post-infectious encephalitis in the other. Three survivors present long-term neurologic or dermatologic sequels. DISCUSSION: Severe cases of chikungunya in children provide a stark reminder of the cardiac and neurological tropism of the virus and its hemorrhagic forms with high potential mortality and morbidity. These cases underline the need for personal protection measures and for research to develop specific antiviral therapy and vaccines to prevent potentially lethal forms of the disease.

[Five-year outcome of mother-to-child transmission of chikungunya virus]. / Devenir a 5 ans des infections materno-foetales a virus chikungunya.

Chikungunya virus is an arbovirus (alphavirus) transmitted by Aedes albopictus in Reunion Island. A huge chikungunya outbreak swept Reunion Island in 2005- 2006. We report the first case of chikungunya neonatal infection and the 5-years outcome of the 18 neonates hospitalized in neonatal intensive care unit between June 2005 and March 2006.

[Coverage of the chikungunya epidemic on Reunion Island in 2006 by the French healthcare system]. / Prise en charge de l'épidémie de chikungunya de 2006 a l'île de la réunion par l'Assurance Maladie.

The chikungunya epidemic that occurred on Reunion Island between 2005 and 2006 was covered by the French health insurance system. This coverage involved a major increase in the number of paid sick leave days and prescription drug refunds in the first quarter of 2006. Special governmental measures such as full reimbursement of certain medications and waiving of the waiting period for sick leave in case of relapse greatly reduced the impact of the epidemic. Five years after, the database of the health insurance systems indicates a low incidence of chronic forms. Only cases managed on an outpatient basis were included in this study.

[Judicial or administrative settlement of medical malpractice claims. Update on medical liability]. / Recours juridictionnels ou administratifs en cas d'accident médical l'actualité de la responsabilité médicale.

Settlement of medical malpractice claims was radically changed by the Kouchner Law that set up a rapid, effective system of indemnification. Victims can choose between conventional court proceedings and a non-judicial conciliation procedure. Choice between the two processes depends on the circumstances of the case.