RESUMEN
The objective of this study was to determine the etiology of febrile illnesses among patients from October 1, 1993 through September 30, 1999, in the urban community of Iquitos in the Amazon River Basin of Peru. Epidemiological and clinical data as well as blood samples were obtained from consenting patients at hospitals, health clinics and private residences. Samples were tested for arboviruses in cell cultures and for IgM and IgG antibodies by ELISA. Blood smears were examined for malaria, and sera were tested for antibodies to Leptospira spp. by ELISA and microscopic agglutination. Among 6,607 febrile patients studied, dengue viruses caused 14.6% of the cases, and Venezuelan equine encephalitis virus caused 2.5%, Oropouche virus 1.0%, Mayaro virus 0.4%, and other arboviruses caused 0.2% of the cases. Also, 22.9% of 4,844 patients tested were positive for malaria, and of 400 samples tested, 9% had evidence of acute leptospirosis. Although the study was not designed to assess the importance of these pathogens as a cause of human morbidity in the total population, these results indicate that arboviruses, leptospirosis, and malaria were the cause of approximately 50% of the febrile cases. Although the arboviruses that were diagnosed can produce asymptomatic infections, our findings increased the overall understanding of the relative health burden of these infections, as well as baseline knowledge needed for designing and implementing further studies to better assess the health impact and threat of these pathogens in the Amazon Basin of Peru.
Asunto(s)
Arbovirus , Virus de la Encefalitis Equina Venezolana , Leptospirosis , Malaria , Humanos , Perú/epidemiología , Ríos , Leptospirosis/epidemiología , Fiebre/epidemiologíaRESUMEN
Lassa virus pathogenesis is believed to involve dysregulation of cytokines. We have previously shown nuclear factor-kappaB (NF-kappaB) inhibition using a BSL-2 model for Lassa fever. Here we further define the potential mechanism for NF-kappaB inhibition as involving increased levels of repressive p50/p50 homodimers, and suggest a novel therapeutic strategy that acts via modulation of host signaling.
Asunto(s)
Infecciones por Arenaviridae/tratamiento farmacológico , Virus Defectuosos/patogenicidad , Monocitos/virología , FN-kappa B/metabolismo , Virus Pichinde/patogenicidad , Animales , Proteína Tirosina Quinasa CSK , Virus Defectuosos/fisiología , Sistemas de Liberación de Medicamentos , Técnicas In Vitro , Ratones , Subunidad p50 de NF-kappa B/metabolismo , Fosforilación , Virus Pichinde/fisiología , Procesamiento Proteico-Postraduccional , Transporte de Proteínas , Proteínas Tirosina Quinasas/metabolismo , Transducción de Señal , Factor de Transcripción ReIA/metabolismo , Transcripción Genética , Virulencia , Familia-src QuinasasRESUMEN
Viral haemorrhagic fever (VHF) is caused by a number of viruses, including arenaviruses. The pathogenesis is believed to involve dysregulation of cytokine production. The arenaviruses Lassa virus and Pichinde virus have a tropism for macrophages and other reticuloendothelial cells and both appear to suppress the normal macrophage response to virus infection. A decoy thioaptamer, XBY-S2, was developed and was found to bind to AP-1 transcription factor proteins. The P388D1 macrophage-like cell line contains members of the AP-1 family which may act as negative regulators of AP-1-controlled transcription. XBY-S2 was found to bind to Fra-2 and JunB, and enhance the induction of cytokines IL-6, IL-8 and TNF-alpha, while reducing the binding to AP-1 promoter elements. Administration of XBY-S2 to Pichinde virus-infected guinea pigs resulted in a significant reduction in Pichinde virus-induced mortality and enhanced the expression of cytokines from primary guinea pig macrophages, which may contribute to its ability to increase survival of Pichinde virus-infected guinea pigs. These data demonstrate a proof of concept that thioaptamers can be used to modulate the outcome of in vivo viral infections by arenaviruses by the manipulation of transcription factors involved in the regulation of the immune response.
Asunto(s)
Aptámeros de Nucleótidos/farmacología , Infecciones por Arenaviridae/inmunología , Citocinas/biosíntesis , Factores Inmunológicos/farmacología , Macrófagos/inmunología , Factor de Transcripción AP-1/metabolismo , Animales , Aptámeros de Nucleótidos/administración & dosificación , Aptámeros de Nucleótidos/metabolismo , Arenavirus , Línea Celular , Células Cultivadas , ADN/metabolismo , Ensayo de Cambio de Movilidad Electroforética , Antígeno 2 Relacionado con Fos/metabolismo , Cobayas , Factores Inmunológicos/administración & dosificación , Masculino , Ratones , Poli I-C/farmacología , Regiones Promotoras Genéticas , Unión Proteica , Proteínas Proto-Oncogénicas c-jun/metabolismo , Porcinos , Factor de Transcripción AP-1/genéticaRESUMEN
El virus de la Fiebre amarilla fue aislado de un mono centinela Cebus el 4 de diciembre de 1964 en el bosque Utinga, cercano a Belém, Brasil. De 30 monos silvestres, dez tenían anticuerpos del mencionado virus. Más de 1.200 muestras procedentes de otros vertebrados fueron comprobadas, sin que se obtuviera indicio alguno de relación con el virus amarílico. No se descubrieron casos humanos. El episodio hubiera quedado ignorado de no haberse ilevado a cabo una vigilancia habitual con respecto a los arbovirus.
Yellow fever virus was isolated from a sentinel Cebus monkey on 4 December 1964 in the Utinga forest near Belém, Brazil. Ten of 30 wild monkeys had Yellow fever antibody. Over 1,200 samples from other vertebrates were tested without evidence of involvement with Yellow fever virus. No human cases were found. The episode would have gone undetected if routine surveillance for arboviruses had not been in progress.
O vírus da Febre amarela foi isolado de um macaco sentinela Cebus em 4 de dezembro de 1964 no bosque Utinga, próximo a Belém, Brasil. De 30 macacos silvestres, dez tinham anticorpos da Febre amarela. Mais de 1.200 amostras procedentes de outros vertebrados foram examinadas sem que se obtivesse indício algum de relação com o vírus da doença. Não foram descobertos casos humanos. O episódio foi descoberto graças à vigilância habitual sobre os arbovírus.
Asunto(s)
Animales , Fiebre Amarilla , Virus de la Fiebre Amarilla , Cebus , Pruebas de Inhibición de Hemaglutinación , Pruebas de NeutralizaciónRESUMEN
The serological diagnosis of infection by flaviviruses is complicated by the presence of flavivirus cross-reactive antibodies that produce false-positive results for flavivirus infections, especially in regions where more than one virus is endemic. Current diagnostic reagents for tick-borne flavivirus infection have been found to cross-react with yellow fever- or dengue virus-positive sera. This study utilized recombinant flavivirus E protein domain 3 (rE-D3) as a diagnostic reagent to differentiate between infection by mosquito- and tick-borne flaviviruses. This study found that the use of rE-D3 in an enzyme-linked immunosorbent assay (ELISA)-based format allowed the differentiation between serum specific for either mosquito- or tick-borne flaviviruses, but not among the members of the tick-borne encephalitis (TBE) serocomplex of flaviviruses. Sera derived against several TBE serocomplex rE-D3 were found to cross-react with heterologous rE-D3 within the TBE serocomplex, but not with those from mosquito-borne flaviviruses, in both Western blots and ELISAs. Mouse hyperimmune sera generated against TBE serocomplex viruses were also found to react specifically with TBE serocomplex rE-D3, but not with rE-D3 from mosquito-borne viruses and vice versa. When a similar test using virus-derived antigen was performed, a loss of both specificity and sensitivity was observed. These results indicate that flavivirus rE-D3 would be a useful reagent for the detection of infection by TBE serocomplex flaviviruses, several of which are potential biothreat agents, but would not provide the ability to differentiate among infections by separate members of the serocomplex.
Asunto(s)
Culicidae/virología , Virus de la Encefalitis Transmitidos por Garrapatas/clasificación , Encefalitis Transmitida por Garrapatas/diagnóstico , Infecciones por Flavivirus/diagnóstico , Flavivirus/clasificación , Proteínas del Envoltorio Viral/análisis , Secuencia de Aminoácidos , Animales , Encéfalo/virología , Diagnóstico Diferencial , Virus de la Encefalitis Transmitidos por Garrapatas/aislamiento & purificación , Ensayo de Inmunoadsorción Enzimática , Flavivirus/aislamiento & purificación , Humanos , Ratones , Datos de Secuencia Molecular , Filogenia , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Proteínas del Envoltorio Viral/químicaRESUMEN
The ability of antisera raised against a candidate Japanese encephalitis virus (JEV) vaccine, ChimeriVax-JE, and the currently licensed vaccine, JE-VAX, to protect against strains of JEV representing the four major genotypes was assessed. Neutralization assays and passive protection studies in mice showed that greatest protection was provided against strains of genotypes II and III, although some protection was also afforded against genotypes I and IV strains. ChimeriVax-JE stimulated protection that was comparable or superior to the JE-VAX control.
Asunto(s)
Virus de la Encefalitis Japonesa (Especie)/inmunología , Encefalitis Japonesa/prevención & control , Inmunización Pasiva , Vacunas contra la Encefalitis Japonesa/inmunología , Animales , Anticuerpos Antivirales/análisis , Anticuerpos Antivirales/biosíntesis , Virus de la Encefalitis Japonesa (Especie)/genética , Encefalitis Japonesa/inmunología , Encefalitis Japonesa/virología , Genotipo , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos ICR , Pruebas de Neutralización , Proteínas Recombinantes de Fusión/inmunología , Análisis de SupervivenciaRESUMEN
Serological diagnosis of West Nile virus (WNV) infection is complicated by extensive antigenic cross-reactivity with other closely related flaviviruses, such as St. Louis encephalitis virus. Here we describe a recombinant, bacterially expressed antigen equivalent to structural domain III of the WNV envelope protein that has allowed clear discrimination of antibody responses to WNV from those against other related flaviviruses in indirect enzyme-linked immunosorbent assays using standardized control antisera and field-collected samples.
Asunto(s)
Anticuerpos Antivirales/sangre , Antígenos Virales/inmunología , Fiebre del Nilo Occidental/diagnóstico , Virus del Nilo Occidental/inmunología , Animales , Ensayo de Inmunoadsorción Enzimática , Humanos , Inmunoglobulina G/sangre , Ratones , Subunidades de Proteína , Conejos , Proteínas Recombinantes/inmunología , Pruebas SerológicasRESUMEN
In 1964, D. H. Clarke defined two antigenic subtypes of Omsk haemorrhagic fever virus (OHFV) based on polyclonal antibody absorption and haemagglutination assays. The current report defines the molecular basis for these antigenic subtypes by comparison of the complete genomes of OHFV strains Kubrin (subtype I) and Bogoluvovska (subtype II). There were six nucleotide differences between these two strains throughout the entire genome and they encoded four amino acid changes including three in the viral envelope (E) protein. Two of these changes were in solvent-exposed regions of domain 3 of the E protein, one of which lies in a region that could easily function in virus-host cell or virus-antibody interactions. These results demonstrate the minimal changes that are required to significantly alter the antigenicity of flaviviruses and also demonstrate the tremendous genetic stability of the tick-borne flaviviruses.
Asunto(s)
Virus de la Encefalitis Transmitidos por Garrapatas/inmunología , Secuencia de Aminoácidos , Virus de la Encefalitis Transmitidos por Garrapatas/clasificación , Virus de la Encefalitis Transmitidos por Garrapatas/genética , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Filogenia , Proteínas del Envoltorio Viral/química , Proteínas de la Matriz Viral/químicaRESUMEN
The Caenorhabditis elegans SEM-5 SH3 domains recognize proline-rich peptide segments with modest affinity. We developed a bivalent peptide ligand that contains a naturally occurring proline-rich binding sequence, tethered by a glycine linker to a disulfide-closed loop segment containing six variable residues. The glycine linker allows the loop segment to explore regions of greatest diversity in sequence and structure of the SH3 domain: the RT and n-Src loops. The bivalent ligand was optimized using phage display, leading to a peptide (PP-G(4)-L) with 1000-fold increased affinity for the SEM-5 C-terminal SH3 domain over that of a natural ligand. NMR analysis of the complex confirms that the peptide loop segment is targeted to the RT and n-Src loops and parts of the beta-sheet scaffold of this SH3 domain. This binding region is comparable to that targeted by a natural non-PXXP peptide to the p67(phox) SH3 domain, a region not known to be targeted in the Grb2 SH3 domain family. PP-G(4)-L may aid in the discovery of additional binding partners of Grb2 family SH3 domains.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales , Proteínas de Caenorhabditis elegans/metabolismo , Péptidos/metabolismo , Dominios Homologos src/fisiología , Secuencia de Aminoácidos , Animales , Sitios de Unión/genética , Proteínas de Caenorhabditis elegans/química , Proteínas de Caenorhabditis elegans/genética , Proteína Adaptadora GRB2 , Ligandos , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Modelos Moleculares , Datos de Secuencia Molecular , Resonancia Magnética Nuclear Biomolecular , Fragmentos de Péptidos/química , Fragmentos de Péptidos/genética , Fragmentos de Péptidos/metabolismo , Biblioteca de Péptidos , Péptidos/síntesis química , Péptidos/química , Fosfoproteínas/química , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Unión Proteica , Estructura Secundaria de Proteína , Proteínas/química , Proteínas/genética , Proteínas/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homología de Secuencia de Aminoácido , Termodinámica , Dominios Homologos src/genéticaRESUMEN
Omsk hemorrhagic fever virus (OHF) is a tick-borne flavivirus endemic to Western Siberia. This virus is the only known tick-borne flavivirus to cause hemorrhagic disease in humans in the absence of encephalitis. OHF virus circulates within a small, defined niche in which other tick-borne complex flaviviruses are also present. The objectives of this study were to genetically classify OHF virus based on its complete genome and to identify genetic determinants that might be involved in tissue tropism and viral replication leading to the disease state caused by this virus. The OHF virus genome was sequenced and phylogenetic analysis demonstrated that OHF virus falls within the tick-borne encephalitis serocomplex of flaviviruses, yet is distinct from other members of the complex, including those closely associated geographically. OHF is also distinct from Alkhurma (ALK) and Kyasanur forest disease (KFD) viruses, both of which cause disease that includes hemorrhagic and encephalitic manifestations. Several amino acid residues were found to be distinct among OHF, KFD, and ALK viruses; these residues include E-76, which is closely associated with the viral envelope protein fusion peptide. In addition, variation between the viral 5'-untranslated region of OHF and other tick-borne flaviviruses suggests potential variability in viral replication. These data demonstrate that OHF is a unique virus among the tick-borne flaviviruses and also provide insight to viral biodiversity and tropism.