RESUMEN
Crimean-Congo haemorrhagic fever (CCHF) is one of the most widespread arboviroses in the world. It is present in Africa, south-east Europe, the Middle East and Asia. It is caused by a nairovirus (Bunyaviridae family) transmitted by several species of ticks. The geographical distribution of the disease coincides with the distribution of Hyalomma ticks. While infected livestock do not show signs of illness, humans are severely affected, with a high mortality rate. The most common symptoms are high fever, dizziness, headache, vomiting and haemorrhages. Pathogenesis studies in interferon-receptor-deficient mice indicated that the interferon response is crucial in controlling virus propagation and in protecting against the disease. Detection of the virus in biological material is currently performed by reverse-transcription polymerase chain reaction. Enzyme-linked immunosorbent assay and indirect immunofluorescence are used to detect the presence of CCHF virus-specific antibodies. In the 1970s, a formalin-inactivated vaccine prepared from suckling mouse brain was used in Eastern Europe and the former Soviet Union, but its efficacy remains to be proven. Treatment of patients with ribavirin is recommended by the World Health Organization, but it should be administered as early as possible. Although important progress has been made over the last few decades, many questions about the pathogenesis and epidemiology of the disease are still to be addressed and there is a need to develop efficient vaccines and antivirals.
Asunto(s)
Virus de la Fiebre Hemorrágica de Crimea-Congo , Fiebre Hemorrágica de Crimea/veterinaria , Animales , Antivirales/uso terapéutico , Enfermedades Transmisibles Emergentes , Virus de la Fiebre Hemorrágica de Crimea-Congo/genética , Fiebre Hemorrágica de Crimea/tratamiento farmacológico , Fiebre Hemorrágica de Crimea/epidemiología , Fiebre Hemorrágica de Crimea/virología , Humanos , Ribavirina/uso terapéuticoRESUMEN
The large variation in individual response to infection with Rift Valley fever virus (RVFV) suggests that host genetic determinants play a role in determining virus-induced disease outcomes. These genetic factors are still unknown. The systemic inoculation of mice with RVFV reproduces major pathological features of severe human disease, notably the hepatitis and encephalitis. A genome scan performed on 546 (BALB/c × MBT) F2 progeny identified three quantitative trait loci (QTLs), denoted Rvfs-1 to Rvfs-3, that were associated with disease susceptibility in MBT/Pas mice. Non-parametric interval-mapping revealed one significant and two suggestive linkages with survival time on chromosomes 2 (Rvfs-1), 5 (Rvfs-3) and 11 (Rvfs-2) with respective logarithm of odds (LOD) scores of 4.58, 2.95 and 2.99. The two-part model, combining survival time and survival/death, identified one significant linkage to Rvfs-2 and one suggestive linkage to Rvfs-1 with respective LOD scores of 5.12 and 4.55. Under a multiple model, with additive effects and sex as a covariate, the three QTLs explained 8.3% of the phenotypic variance. Sex had the strongest influence on susceptibility. The contribution of Rvfs-1, Rvfs-2 and Rvfs-3 to survival time of RVFV-infected mice was further confirmed in congenic mice.
Asunto(s)
Predisposición Genética a la Enfermedad , Fiebre del Valle del Rift/genética , Fiebre del Valle del Rift/virología , Virus de la Fiebre del Valle del Rift , Animales , Modelos Animales de Enfermedad , Susceptibilidad a Enfermedades , Femenino , Marcadores Genéticos , Estudio de Asociación del Genoma Completo , Haplotipos , Escala de Lod , Masculino , Ratones , Fenotipo , Polimorfismo Genético , Sitios de Carácter Cuantitativo , Fiebre del Valle del Rift/mortalidadRESUMEN
Rift Valley fever virus (RVFV) is a re-emerging zoonotic bunyavirus of the genus Phlebovirus. A natural isolate containing a large attenuating deletion in the small (S) genome segment previously yielded a highly effective vaccine virus, named Clone 13. The deletion in the S segment abrogates expression of the NSs protein, which is the major virulence factor of the virus. To develop a vaccine of even higher safety, a virus named R566 was created by natural laboratory reassortment. The R566 virus combines the S segment of the Clone 13 virus with additional attenuating mutations on the other two genome segments M and L, derived from the previously created MP-12 vaccine virus. To achieve the same objective, a nonspreading RVFV (NSR-Gn) was created by reverse-genetics, which not only lacks the NSs gene but also the complete M genome segment. We have now compared the vaccine efficacies of these two next-generation vaccines and included the Clone 13 vaccine as a control for optimal efficacy. Groups of eight lambs were vaccinated once and challenged three weeks later. All mock-vaccinated lambs developed high fever and viremia and three lambs did not survive the infection. As expected, lambs vaccinated with Clone 13 were protected from viremia and clinical signs. Two lambs vaccinated with R566 developed mild fever after challenge infection, which was associated with low levels of viral RNA in the blood, whereas vaccination with the NSR-Gn vaccine completely prevented viremia and clinical signs.
Asunto(s)
Fiebre del Valle del Rift/prevención & control , Enfermedades de las Ovejas/prevención & control , Vacunas Virales/inmunología , Animales , Anticuerpos Antivirales/sangre , Pruebas de Neutralización , ARN Viral/sangre , Distribución Aleatoria , Virus Reordenados/inmunología , Virus de la Fiebre del Valle del Rift/inmunología , Ovinos/inmunología , Enfermedades de las Ovejas/virología , Vacunas Atenuadas/inmunología , ViremiaRESUMEN
Vaccination continues to be the most effective way to control Rift Valley fever (RVF), a zoonotic insect-borne viral disease of livestock. The irregular, cyclical and persistent nature of RVF in its occurrence in enzootic situations suggests that the vaccination strategy to be considered for these regions should be different from what is envisaged for free from risk regions. Currently available RVF vaccines have been extensively used for the control of the disease. However, these vaccines have shortcomings that have encouraged many research groups to develop new vaccine candidates that would address a large number of the current challenges, and be suitable for use both in disease-free regions and in different contingency and emergency preparedness strategies. The characteristics of different RVF vaccines and vaccination strategies are discussed in this report.
Asunto(s)
Brotes de Enfermedades/veterinaria , Fiebre del Valle del Rift/veterinaria , Vacunas Virales/inmunología , Animales , Brotes de Enfermedades/prevención & control , Salud Global , Humanos , Esquemas de Inmunización , Fiebre del Valle del Rift/diagnóstico , Fiebre del Valle del Rift/prevención & control , VacunaciónRESUMEN
Rift Valley fever virus (RVFV) is a Phlebovirus (Bunyaviridae family) transmitted by mosquitoes. It infects humans and ruminants, causing dramatic epidemics and epizootics in Africa, Yemen, and Saudi Arabia. While recent studies demonstrated the importance of the nonstructural protein NSs as a major component of virulence in vertebrates, little is known about infection of mosquito vectors. Here we studied RVFV infection in three different mosquito cell lines, Aag2 cells from Aedes aegypti and U4.4 and C6/36 cells from Aedes albopictus. In contrast with mammalian cells, where NSs forms nuclear filaments, U4.4 and Aag2 cells downregulated NSs expression such that NSs filaments were never formed in nuclei of U4.4 cells and disappeared at an early time postinfection in the case of Aag2 cells. On the contrary, in C6/36 cells, NSs nuclear filaments were visible during the entire time course of infection. Analysis of virus-derived small interfering RNAs (viRNAs) by deep sequencing indicated that production of viRNAs was very low in C6/36 cells, which are known to be Dicer-2 deficient but expressed some viRNAs presenting a Piwi signature. In contrast, Aag2 and U4.4 cells produced large amounts of viRNAs predominantly matching the S segment and displaying Dicer-2 and Piwi signatures. Whereas 21-nucleotide (nt) Dicer-2 viRNAs were prominent during early infection, the population of 24- to 27-nt Piwi RNAs (piRNAs) increased progressively and became predominant later during the acute infection and during persistence. In Aag2 and U4.4 cells, the combined actions of the Dicer-2 and Piwi pathways triggered an efficient antiviral response permitting, among other actions, suppression of NSs filament formation and allowing establishment of persistence. In C6/36 cells, Piwi-mediated RNA interference (RNAi) appeared to be sufficient to mount an antiviral response against a secondary infection with a superinfecting virus. This study provides new insights into the role of Dicer and Piwi in mosquito antiviral defense and the development of the antiviral response in mosquitoes.
Asunto(s)
Aedes/virología , Proteínas Argonautas/metabolismo , Proteínas de Insectos/metabolismo , ARN Helicasas/metabolismo , Interferencia de ARN , Virus de la Fiebre del Valle del Rift/inmunología , Aedes/inmunología , Animales , Línea Celular , Regulación hacia Abajo , Perfilación de la Expresión Génica , Secuenciación de Nucleótidos de Alto Rendimiento , ARN Viral/biosíntesis , ARN Viral/genética , Virus de la Fiebre del Valle del Rift/genética , Proteínas no Estructurales Virales/biosíntesisRESUMEN
Nuclear architecture as well as gene nuclear positioning can modulate gene expression. In this work, we have analyzed the nuclear position of the interferon-ß (IFN-ß) locus, responsible for the establishment of the innate antiviral response, with respect to pericentromeric heterochromatin (PCH) in correlation with virus-induced IFN-ß gene expression. Experiments were carried out in two different cell types either non-infected (NI) or during the time course of three different viral infections. In NI cells, we showed a monoallelic IFN-ß promoter association with PCH that strongly decreased after viral infection. Dissociation of the IFN-ß locus away from these repressive regions preceded strong promoter transcriptional activation and was reversible within 12 h after infection. No dissociation was observed after infection with a virus that abnormally maintained the IFN-ß gene in a repressed state. Dissociation induced after virus infection specifically targeted the IFN-ß locus without affecting the general structure and nuclear distribution of PCH clusters. Using cell lines stably transfected with wild-type or mutated IFN-ß promoters, we identified the proximal region of the IFN-ß promoter containing YY1 DNA-binding sites as the region regulating IFN-ß promoter association with PCH before as well as during virus infection.
Asunto(s)
Heterocromatina/química , Interferón beta/genética , Factor de Transcripción YY1/metabolismo , Animales , Sitios de Unión , Línea Celular , ADN Satélite/análisis , Ratones , Virus de la Enfermedad de Newcastle/fisiología , Regiones Promotoras Genéticas , Virus de la Fiebre del Valle del Rift/fisiología , Activación TranscripcionalRESUMEN
OBJECTIVES: To detect the presence of Toscana virus (TOSV) circulation in Tunisia and to study its role in viral meningo-encephalitis. PATIENTS AND METHODS: A total of 315 (167 sera and 178 cerobrospinal fluid [CSF]) samples was investigated. These samples are colleted from Tunisian patients with neurological diseases during the period between January 2003 and December 2009. All samples were tested negative for enterovirus, Herpes Simplex virus and West Nile virus. Detection for IgM and IgG specific to TOSV was done by ELISA tests. RESULTS: Specific IgM for TOSV were detected in 10 % of patients with neurological diseases (31 cases). These recent infections were distributed throughout the study period and predominated during summer and automn. Patients were originated, in the majority from the coastal region. IgG were isolated in 22 cases (7 %) corresponding to previous infection. CONCLUSION: This is the first report of TOSV circulating in Tunisia and its frequent implication in neurological diseases. These results incited to include TOSV as one of the viral etiologies to target in the diagnosis of viral meningitis and encephalitis in the country.
Asunto(s)
Encefalitis/etiología , Meningitis/etiología , Virus de Nápoles de la Fiebre de la Mosca de los Arenales/fisiología , Adolescente , Adulto , Anciano , Infecciones por Bunyaviridae/complicaciones , Infecciones por Bunyaviridae/virología , Niño , Preescolar , Encefalitis/epidemiología , Encefalitis/virología , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Meningitis/epidemiología , Meningitis/virología , Meningitis Viral/complicaciones , Meningitis Viral/virología , Persona de Mediana Edad , Virus de Nápoles de la Fiebre de la Mosca de los Arenales/aislamiento & purificación , Estaciones del Año , Estudios Seroepidemiológicos , Caracteres Sexuales , Factores de Tiempo , Túnez/epidemiología , Adulto JovenRESUMEN
During the last decade Crimean-Congo hemorrhagic fever (CCHF) emerged and/or re-emerged in several Balkan countries, Turkey, southwestern regions of the Russian Federation, and the Ukraine, with considerable high fatality rates. Reasons for re-emergence of CCHF include climate and anthropogenic factors such as changes in land use, agricultural practices or hunting activities, movement of livestock that may influence host-tick-virus dynamics. In order to be able to design prevention and control measures targeted at the disease, mapping of endemic areas and risk assessment for CCHF in Europe should be completed. Furthermore, areas at risk for further CCHF expansion should be identified and human, vector and animal surveillance be strengthened.
Asunto(s)
Fiebre Hemorrágica de Crimea/epidemiología , Animales , Europa (Continente)/epidemiología , Fiebre Hemorrágica de Crimea/diagnóstico , Fiebre Hemorrágica de Crimea/tratamiento farmacológico , Fiebre Hemorrágica de Crimea/mortalidad , Fiebre Hemorrágica de Crimea/prevención & control , Humanos , Vigilancia de la Población , Medición de Riesgo , Garrapatas/microbiologíaRESUMEN
Rift Valley fever virus (RVFV) is an emerging, highly pathogenic virus; RVFV infection can lead to encephalitis, retinitis, or fatal hepatitis associated with hemorrhagic fever in humans, as well as death, abortions, and fetal deformities in animals. RVFV nonstructural NSs protein, a major factor of the virulence, forms filamentous structures in the nuclei of infected cells. In order to further understand RVFV pathology, we investigated, by chromatin immunoprecipitation, immunofluorescence, fluorescence in situ hybridization, and confocal microscopy, the capacity of NSs to interact with the host genome. Our results demonstrate that even though cellular DNA is predominantly excluded from NSs filaments, NSs interacts with some specific DNA regions of the host genome such as clusters of pericentromeric gamma-satellite sequence. Targeting of these sequences by NSs was correlated with the induction of chromosome cohesion and segregation defects in RVFV-infected murine, as well as sheep cells. Using recombinant nonpathogenic virus rZHDeltaNSs210-230, expressing a NSs protein deleted of its region of interaction with cellular factor SAP30, we showed that the NSs-SAP30 interaction was essential for NSs to target pericentromeric sequences, as well as for induction of chromosome segregation defects. The effect of RVFV upon the inheritance of genetic information is discussed with respect to the pathology associated with fetal deformities and abortions, highlighting the main role played by cellular cofactor SAP30 on the establishment of NSs interactions with host DNA sequences and RVFV pathogenesis.
Asunto(s)
Centrómero/genética , ADN Satélite/metabolismo , Interacciones Huésped-Patógeno , Virus de la Fiebre del Valle del Rift/patogenicidad , Proteínas no Estructurales Virales/metabolismo , Animales , Línea Celular , Chlorocebus aethiops , Inmunoprecipitación de Cromatina , Segregación Cromosómica/fisiología , ADN Satélite/genética , Técnica del Anticuerpo Fluorescente , Histona Desacetilasas/metabolismo , Hibridación Fluorescente in Situ , Ratones , Microscopía Confocal , Virus de la Fiebre del Valle del Rift/genética , Virus de la Fiebre del Valle del Rift/metabolismo , Ovinos , Células Vero , Proteínas no Estructurales Virales/genética , VirulenciaRESUMEN
Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease described in more than 30 countries in Europe, Asia and Africa. The causative agent is the Crimean-Congo hemorrhagic fever virus (CCHFV) that is a member of the genus Nairovirus of the family Bunyaviridae. CCHFV that is characterized by a high genetic variability is transmitted to humans by tick bites or contact with fluids from an infected individual or animal. The initial symptoms of CCHF are nonspecific and gradually progress to a hemorrhagic phase that can be lethal (case-fatality rate: 10 to 50%). Characteristic laboratory findings of CCHF are thrombocytopenia, elevated liver and muscle enzymes, and coagulation defects. The pathogenesis of CCHF remains unclear but might involve excessive pro-inflammatory cytokine production and dysfunction of the innate immune response. Diagnosis of CCHF is based mainly on isolation of the virus, identification of the viral genome by molecular techniques (RT-PCR), and serological detection of anti-CCHFV antibodies. There is currently no specific treatment for CCHFV infection and the efficacy of ribavirin is controversial. In absence of an effective vaccine, prevention is based mainly on vector control, protection measures, and information to increase the awareness of the population and of healthcare workers.
Asunto(s)
Fiebre Hemorrágica de Crimea/diagnóstico , Fiebre Hemorrágica de Crimea/transmisión , Animales , Antivirales/uso terapéutico , Vectores Arácnidos/virología , Diagnóstico Diferencial , Virus de la Fiebre Hemorrágica de Crimea-Congo/patogenicidad , Fiebre Hemorrágica de Crimea/tratamiento farmacológico , Fiebre Hemorrágica de Crimea/epidemiología , Humanos , Ribavirina/uso terapéutico , Garrapatas/virologíaRESUMEN
Arboviruses are arthropod-borne viruses, which include West Nile fever virus (WNFV), a mosquito-borne virus, Rift Valley fever virus (RVFV), a mosquito-borne virus, and Crimean-Congo haemorrhagic fever virus (CCHFV), a tick-borne virus. These arthropod-borne viruses can cause disease in different domestic and wild animals and in humans, posing a threat to public health because of their epidemic and zoonotic potential. In recent decades, the geographical distribution of these diseases has expanded. Outbreaks of WNF have already occurred in Europe, especially in the Mediterranean basin. Moreover, CCHF is endemic in many European countries and serious outbreaks have occurred, particularly in the Balkans, Turkey and Southern Federal Districts of Russia. In 2000, RVF was reported for the first time outside the African continent, with cases being confirmed in Saudi Arabia and Yemen. This spread was probably caused by ruminant trade and highlights that there is a threat of expansion of the virus into other parts of Asia and Europe. In the light of global warming and globalisation of trade and travel, public interest in emerging zoonotic diseases has increased. This is especially evident regarding the geographical spread of vector-borne diseases. A multi-disciplinary approach is now imperative, and groups need to collaborate in an integrated manner that includes vector control, vaccination programmes, improved therapy strategies, diagnostic tools and surveillance, public awareness, capacity building and improvement of infrastructure in endemic regions.
Asunto(s)
Infecciones por Arbovirus/prevención & control , Vectores Artrópodos , Enfermedades Transmisibles Emergentes/prevención & control , Agencias Internacionales/organización & administración , Zoonosis/epidemiología , África/epidemiología , Animales , Infecciones por Arbovirus/epidemiología , Infecciones por Arbovirus/transmisión , Asia/epidemiología , Comercio , Enfermedades Transmisibles Emergentes/epidemiología , Enfermedades Transmisibles Emergentes/transmisión , Enfermedades Endémicas , Europa (Continente)/epidemiología , Educación en Salud , Fiebre Hemorrágica de Crimea/epidemiología , Fiebre Hemorrágica de Crimea/prevención & control , Fiebre Hemorrágica de Crimea/transmisión , Humanos , Control de Mosquitos/organización & administración , Vigilancia de la Población , Fiebre del Valle del Rift/epidemiología , Fiebre del Valle del Rift/prevención & control , Fiebre del Valle del Rift/transmisión , Rumiantes , Fiebre del Nilo Occidental/epidemiología , Fiebre del Nilo Occidental/prevención & control , Fiebre del Nilo Occidental/transmisiónRESUMEN
Epidemiological data from bank voles, Myodes glareolus, naturally infected by the hantavirus Puumala (PUUV) were collected by a capture-mark-recapture protocol from 2000 to 2002 in the French department of Ardennes. Four monitored trapping sites were established in two forests located in two cantons (Flize and Monthermé). We captured 912 bank voles corresponding to 557 different individuals during 8820 trapping nights for an overall trapping success of 10.34%. The average PUUV seroprevalence was 22.4%. Characteristics of the system reported in North European countries are confirmed in France. PUUV seroprevalence and abundance of rodents appeared weakly linked. Adult voles were more frequently antibody-positive, but no difference between sexes was established. Anti-PUUV seropositive voles were captured and high seroprevalence was observed from both forests, without human infection reported in Flize canton during the study. One site among the four exhibited peculiar infection dynamics, where vole weight and infection risk were negatively correlated.
Asunto(s)
Arvicolinae/virología , Fiebre Hemorrágica con Síndrome Renal/veterinaria , Virus Puumala/fisiología , Animales , Anticuerpos Antivirales/sangre , Demografía , Femenino , Francia/epidemiología , Fiebre Hemorrágica con Síndrome Renal/epidemiología , Masculino , Densidad de Población , Estudios Seroepidemiológicos , Factores de TiempoRESUMEN
Crimean-Congo hemorrhagic fever virus (CCHFV) is transmitted to humans by ticks or by direct contact with infected blood. It causes severe, often fatal, hemorrhagic diseases in humans but infection in animals is asymptomatic. CCHFV can spread from person to person and has caused many nosocomial outbreaks. Because the virus is very pathogenic for humans it must be manipulated in a biosafety level 4 (BSL4) laboratory, rendering the production of antigen for serological diagnosis difficult. To replace the native antigen, we produced a recombinant nucleoprotein expressed in mammalian cells via the recombinant Semliki Forest alphavirus replicon and developed an indirect immunofluorescence assay (IFA) as well as an enzyme-linked immunosorbent assay (ELISA) by immunocapture to detect IgM and IgG in human and animal serum. Using these methods, we analyzed clinical samples from human patients and sera from domestic animals collected in Iran and we show that this novel antigen provides a novel, sensitive and specific tool for CCHF diagnosis.
Asunto(s)
Virus de la Fiebre Hemorrágica de Crimea-Congo/inmunología , Fiebre Hemorrágica de Crimea/diagnóstico , Inmunoglobulina G/sangre , Inmunoglobulina M/sangre , Animales , Anticuerpos Antivirales/sangre , Antígenos Virales , Ensayo de Inmunoadsorción Enzimática/métodos , Virus de la Fiebre Hemorrágica de Crimea-Congo/química , Fiebre Hemorrágica de Crimea/epidemiología , Humanos , Irán/epidemiología , Proteínas Recombinantes/inmunología , Virus de los Bosques Semliki/metabolismo , Sensibilidad y EspecificidadRESUMEN
This paper describes the production and characterization of RVFV monoclonal antibodies. The characteristics of 32 out of 55 ELISA and/or IFA positive monoclonal antibodies were determined, including the RVFV components against which they are directed. One monoclonal antibody recognized the nucleoprotein, 15 the Gc and 16 the Gn. Among the latter ones, five monoclonal antibodies possess another specificity and recognized both Gn and either the nucleoprotein (four of them) or the NSs protein (one). To validate the use of these monoclonal antibodies for diagnosis tests, a pool of monoclonal antibodies reacting with the structural proteins was prepared and used successfully to detect RVFV from cell culture as well as viral antigen-antibody complex in ELISA.
Asunto(s)
Anticuerpos Antivirales/biosíntesis , Fiebre del Valle del Rift/diagnóstico , Virus de la Fiebre del Valle del Rift/inmunología , Virus de la Fiebre del Valle del Rift/aislamiento & purificación , Animales , Anticuerpos Monoclonales/biosíntesis , Anticuerpos Monoclonales/inmunología , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/inmunología , Especificidad de Anticuerpos , Complejo Antígeno-Anticuerpo/análisis , Antígenos Virales/inmunología , Ensayo de Inmunoadsorción Enzimática/métodos , Femenino , Humanos , Inmunoglobulina G , Inmunoglobulina M , Ratones , Ratones Endogámicos BALB C , Nucleoproteínas/inmunología , Fiebre del Valle del Rift/sangre , Fiebre del Valle del Rift/virologíaRESUMEN
Puumala virus (Bunyaviridae family, Hantavirus genus) causes a mild form of hemorrhagic fever with renal syndrome (HFRS) called nephropathia epidemica in northern and central Europe. Serological tests are used for diagnosis, but antigen production is difficult because the virus grows poorly in tissue culture. We expressed the N protein (nucleoprotein) of Puumala virus via the Semliki Forest virus (SFV) replicon in mammalian cells and compared its antigenic properties with those of the native antigen derived from Puumala virus-infected cells. Detection of immunoglobulin G or immunoglobulin M by enzyme-linked immunosorbent assay (ELISA), micro -capture ELISA, and indirect immunofluorescence assay was (at least) as effective with the recombinant antigen as with the native antigen when HFRS patient sera or organ washes from wild rodents were tested. No nonspecific reaction was observed. Thus, the SFV-expressed N protein of Puumala virus appears as a valid antigen, specific and sensitive for serological investigations.
Asunto(s)
Anticuerpos Antivirales/análisis , Antígenos Virales/biosíntesis , Ensayo de Inmunoadsorción Enzimática , Fiebre Hemorrágica con Síndrome Renal/diagnóstico , Inmunoglobulina G/análisis , Inmunoglobulina M/análisis , Nucleocápside/biosíntesis , Virus Puumala/genética , Virus de los Bosques Semliki/genética , Animales , Anticuerpos Antivirales/inmunología , Especificidad de Anticuerpos , Antígenos Virales/genética , Antígenos Virales/inmunología , Arvicolinae/virología , Cricetinae , Reservorios de Enfermedades , Fiebre Hemorrágica con Síndrome Renal/sangre , Fiebre Hemorrágica con Síndrome Renal/virología , Humanos , Inmunoglobulina G/inmunología , Inmunoglobulina M/inmunología , Microscopía Fluorescente , Nucleocápside/genética , Proteínas de la Nucleocápside , Proteínas Recombinantes de Fusión/biosíntesis , Proteínas Recombinantes de Fusión/genética , ReplicónRESUMEN
For three years the arbovirus surveillance unit of the Tropical Medicine Institute of the French Army Medical Corps (French acronym IMTSSA) in Marseille, France has been investigating causes of benign non-malarial febrile syndromes in French military personnel serving outside mainland France. The methodology used in N'Djamena consisted of sending frozen specimens collected concomitant with viremia, to Marseille for culture. During the rainy season of 2001, specimens were collected from a total of 50 febrile soldiers. Cultures allowed isolation and identification of two strains of Rift Valley virus. The risk of contamination exists not only in the field but also in mainland hospital departments treating infected patients. Routine serological diagnosis for Rift Valley fever must be DISCUSSED for all patients in the field or returning from Africa.
Asunto(s)
Brotes de Enfermedades , Personal Militar , Fiebre del Valle del Rift/epidemiología , Adulto , África , Francia , Hospitales Militares , Humanos , Fiebre del Valle del Rift/diagnóstico , Pruebas SerológicasRESUMEN
Reverse transcriptase PCR (RT-PCR) for diagnosis of Rift Valley fever (RVF) was evaluated by using 293 human and animal sera sampled during an RVF outbreak in Mauritania in 1998. Results of the RT-PCR diagnostic method were compared with those of virus isolation (VI) and detection of immunoglobulin M (IgM) antibodies. Our results showed that RT-PCR is a specific, sensitive tool for RVF diagnosis in the early phase of the disease and that its results do not differ significantly from those obtained by VI. Moreover, the combined results of RT-PCR and IgM antibody detection were in 100% concordance with the results of VI.
Asunto(s)
Brotes de Enfermedades , ARN Viral/sangre , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Fiebre del Valle del Rift/diagnóstico , Animales , Anticuerpos Antivirales/inmunología , Camelus , Bovinos , Línea Celular , Francia/epidemiología , Cabras , Humanos , Inmunoglobulina M/inmunología , ADN Polimerasa Dirigida por ARN , Fiebre del Valle del Rift/epidemiología , Fiebre del Valle del Rift/veterinaria , Fiebre del Valle del Rift/virología , Virus de la Fiebre del Valle del Rift/genética , Virus de la Fiebre del Valle del Rift/inmunología , Virus de la Fiebre del Valle del Rift/aislamiento & purificación , Ovinos , Proteínas no Estructurales Virales/genéticaRESUMEN
The Rift Valley fever virus (RVFV), a member of the genus Phlebovirus (family Bunyaviridae) is an enveloped negative-strand RNA virus with a tripartite genome. Until 2000, RVFV circulation was limited to the African continent, but the recent deadly outbreak in the Arabian Peninsula dramatically illustrated the need for rapid diagnostic methods, effective treatments, and prophylaxis. A method for quantifying the small RNA segment by a real-time detection reverse transcription (RT)-PCR using TaqMan technology and targeting the nonstructural protein-coding region was developed, and primers and a probe were designed. After optimization of the amplification reaction and establishment of a calibration curve with synthetic RNA transcribed in vitro from a plasmid containing the gene of interest, real-time RT-PCR was assessed with samples consisting of RVFV from infected Vero cells. The method was found to be specific for RVFV, and it was successfully applied to the detection of the RVFV genome in animal sera infected with RVFV as well as to the assessment of the efficiency of various drugs (ribavirin, alpha interferon, 6-azauridine, and glycyrrhizin) for antiviral activity. Altogether, the results indicated a strong correlation between the infectious virus titer and the amount of viral genome assayed by real time RT-PCR. This novel method could be of great interest for the rapid diagnosis and screening of new antiviral compounds, as it is sensitive and time saving and does not require manipulation of infectious material.
Asunto(s)
Antivirales/farmacología , ARN Viral , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Fiebre del Valle del Rift/virología , Virus de la Fiebre del Valle del Rift/efectos de los fármacos , Virus de la Fiebre del Valle del Rift/aislamiento & purificación , Animales , Línea Celular , Chlorocebus aethiops , Humanos , Ratones , Pruebas de Sensibilidad Microbiana , ARN Viral/análisis , ARN Viral/sangre , Virus de la Fiebre del Valle del Rift/genética , Células VeroRESUMEN
An increasing number of clinical cases of Hantavirus infections have been reported from various regions in Asia, Europe and North America. Hantaviruses (family Bunyaviridae, genus Hantavirus) are enveloped and possess a single-stranded trisegmented RNA genome of negative polarity. Rodents or insectivores are natural hosts of hantaviruses and transmit the virus to humans chiefly by aerosolisation. These viruses are the causative agents of haemorrhagic fever with renal and pulmonary syndromes. In the northeast of France, Puumala hantavirus causes, every year, more than 150 mild forms of haemorrhagic fever with a renal syndrome known as nephropathia epidemica. Serological tests may lack sensitivity for diagnosing early stages of infection and virus isolation is limited because it grows poorly in cell culture. Since reverse transcription (RT)-PCR amplification is an efficient method for detecting viral genomes in patient specimens, we developed an assay using a Taqman probe and compared it with the classical RT-PCR amplification. To achieve this goal, a Puumala strain was grown in Vero E6 cells and RNA extracted from the culture supernatant. We found that the semi-nested RT-PCR detected a minimal amount of 300 TCID(50) mL(-1), while the Taqman PCR allowed detection of less than 10 TCID(50) mL(-1 )and provided a quantitative analysis.