RESUMEN
In 1998, Nipah virus (NV) emerged in peninsular Malaysia, causing fatal encephalitis in humans and a respiratory disease in swine. NV is most closely related to Hendra virus (HV), a paramyxovirus that was identified in Australia in 1994, and it has been proposed that HV and NV represent a new genus within the family Paramyxoviridae. This report describes the analysis of the sequences of the polymerase gene (L) and genomic termini of NV as well as a comparison of the full-length, genomic sequences of HV and NV. The L gene of NV is predicted to be 2244 amino acids in size and contains the six domains found within the L proteins of all nonsegmented, negative-stranded (NNS) RNA viruses. However, the GDNQ motif found in most NNS RNA viruses was replaced by GDNE in both NV and HV. The 3' and 5' termini of the NV genome are nearly identical to the genomic termini of HV and share sequence homology with the genomic termini of other members of the subfamily Paramyxovirinae. At 18,246 nucleotides, the genome of NV is 12 nucleotides longer than the genome of HV and they have the largest genomes within the family Paramyxoviridae. The comparison of the structures of the genomes of HV and NV is now complete and this information will help to establish the taxonomic position of these novel viruses within the family Paramyxoviridae.
Asunto(s)
ARN Polimerasas Dirigidas por ADN/genética , Genoma Viral , Paramyxovirinae/genética , Proteínas Virales/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Chlorocebus aethiops , ARN Polimerasas Dirigidas por ADN/química , Humanos , Malasia , Datos de Secuencia Molecular , Paramyxovirinae/clasificación , Paramyxovirinae/enzimología , Filogenia , Técnica del ADN Polimorfo Amplificado Aleatorio , Porcinos , Células Vero , Proteínas Virales/químicaRESUMEN
The structure and genetic organization of Hendra and Nipah viruses places them in the subfamily Paramyxovirinae. However, low homology with other subfamily members and several novel biological and molecular features such as genome length and F(0 )cleavage site suggest classification in a new genus within the Paramyxovirinae.
Asunto(s)
Genoma Viral , Paramyxovirinae/clasificación , Paramyxovirinae/genética , Proteínas Virales/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Genes Virales , Humanos , Datos de Secuencia Molecular , Filogenia , Análisis de Secuencia de ADN , Proteínas Virales/química , Proteínas Virales/metabolismoRESUMEN
Recently, a new paramyxovirus, now known as Nipah virus (NV), emerged in Malaysia and Singapore, causing fatal encephalitis in humans and a respiratory syndrome in pigs. Initial studies had indicated that NV is antigenically and genetically related to Hendra virus (HV). We generated the sequences of the N, P/C/V, M, F, and G genes of NV and compared these sequences with those of HV and other members of the family Paramyxoviridae. The intergenic regions of NV were identical to those of HV, and the gene start and stop sequences of NV were nearly identical to those of HV. The open reading frames (ORFs) for the V and C proteins within the P gene were found in NV, but the ORF encoding a potential short basic protein found in the P gene of HV was not conserved in NV. The N, P, C, V, M, F, and G ORFs in NV have nucleotide homologies ranging from 88% to 70% and predicted amino acid homologies ranging from 92% to 67% in comparison with HV. The predicted fusion cleavage sequence of the F protein of NV had a single amino acid substitution (K to R) in comparison with HV. Phylogenetic analysis demonstrated that although HV and NV are closely related, they are clearly distinct from any of the established genera within the Paramyxoviridae and should be considered a new genus.
Asunto(s)
Paramyxovirinae/genética , Secuencia de Aminoácidos , Animales , Chlorocebus aethiops , Clonación Molecular , Glicoproteínas/genética , Ratones , Datos de Secuencia Molecular , Nucleoproteínas/genética , Paramyxovirinae/clasificación , Fosfoproteínas/genética , Filogenia , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Transcripción Genética , Células Vero , Proteínas Virales de Fusión/genética , Proteínas de la Matriz Viral/genética , Proteínas Virales/genéticaRESUMEN
A paramyxovirus virus termed Nipah virus has been identified as the etiologic agent of an outbreak of severe encephalitis in people with close contact exposure to pigs in Malaysia and Singapore. The outbreak was first noted in late September 1998 and by mid-June 1999, more than 265 encephalitis cases, including 105 deaths, had been reported in Malaysia, and 11 cases of encephalitis or respiratory illness with one death had been reported in Singapore. Electron microscopic, serologic, and genetic studies indicate that this virus belongs to the family Paramyxoviridae and is most closely related to the recently discovered Hendra virus. We suggest that these two viruses are representative of a new genus within the family Paramyxoviridae. Like Hendra virus, Nipah virus is unusual among the paramyxoviruses in its ability to infect and cause potentially fatal disease in a number of host species, including humans.
Asunto(s)
Encefalitis Viral/virología , Infecciones por Paramyxoviridae/epidemiología , Infecciones por Paramyxoviridae/virología , Paramyxovirinae , Animales , Anticuerpos Antivirales/sangre , Brotes de Enfermedades , Encefalitis Viral/epidemiología , Endotelio Vascular/patología , Endotelio Vascular/virología , Genes Virales , Células Gigantes/patología , Células Gigantes/virología , Humanos , Malasia/epidemiología , Microscopía Electrónica , Datos de Secuencia Molecular , Nucleocápside/ultraestructura , Infecciones por Paramyxoviridae/transmisión , Infecciones por Paramyxoviridae/veterinaria , Paramyxovirinae/clasificación , Paramyxovirinae/genética , Paramyxovirinae/aislamiento & purificación , Paramyxovirinae/ultraestructura , Filogenia , Sistema Respiratorio/virología , Infecciones del Sistema Respiratorio/epidemiología , Infecciones del Sistema Respiratorio/veterinaria , Infecciones del Sistema Respiratorio/virología , Análisis de Secuencia de ADN , Singapur/epidemiología , Porcinos , Enfermedades de los Porcinos/epidemiología , Enfermedades de los Porcinos/virología , Vasculitis/virología , Proteínas Virales/genéticaRESUMEN
Ebola virus infection is highly lethal and leads to severe immunosuppression. In this study, we demonstrate that infection of human umbilical vein endothelial cells (HUVECs) with Ebola virus Zaire (EZ) suppressed basal expression of the major histocompatibility complex class I (MHC I) family of proteins and inhibited the induction of multiple genes by alpha interferon (IFN-alpha) and IFN-gamma, including those coding for MHC I proteins, 2'-5' oligoadenylate synthetase [2'-5'(A)N], and IFN regulatory factor 1 (IRF-1). Induction of interleukin-6 (IL-6) and ICAM-1 by IL-1beta was not suppressed by infection with EZ, suggesting that the inhibition of IFN signaling is specific. Gel shift analysis demonstrated that infection with EZ blocked the induction by IFNs of nuclear proteins that bind to IFN-stimulated response elements, gamma activation sequences, and IFN regulatory factor binding site (IRF-E). In contrast, infection with EZ did not block activation of the transcription factor NF-kappaB by IL-1beta. The events that lead to the blockage of IFN signaling may be critical for Ebola virus-induced immunosuppression and would play a role in the pathogenesis of Ebola virus infection.
Asunto(s)
Antivirales/farmacología , Ebolavirus/genética , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/virología , Regulación Viral de la Expresión Génica , Fiebre Hemorrágica Ebola/tratamiento farmacológico , Fiebre Hemorrágica Ebola/genética , Interferón-alfa/farmacología , Interferón gamma/farmacología , Interleucina-1/farmacología , Antivirales/uso terapéutico , Células Cultivadas , Resistencia a Medicamentos , Humanos , Interferón-alfa/uso terapéutico , Interferón gamma/uso terapéutico , Interleucina-1/uso terapéuticoRESUMEN
The expression of intercellular adhesion molecule 1 (ICAM-1) by endothelial cells is important for the regulation of adhesion and transendothelial migration of a variety of leukocytes that express the integrins lymphocyte function-associated antigen 1 (LFA-1) and/or Mac-1. Here, we demonstrate strain-specific differences in the ability of measles virus (MV) to induce ICAM-1 expression. The vaccine strain Moraten (Mor) rapidly induced high levels of ICAM-1 mRNA and protein expression, whereas the vaccine strain CAM-70 and the Edmonston wild type (Ed-wt) strain were far less effective, even when they were used at very high multiplicities of infection (MOIs). Strain-specific differences in the induction were not a consequence of differences in the ability to infect ECs. Furthermore, induction of ICAM-1 by Mor was not dependent on de novo expression of MV or cellular proteins. Dual-immunofluorescence analysis indicated that there was no association between the expression of either MV nucleocapsid or hemagglutinin protein and the induction of ICAM-1 expression. Some human umbilical vein endothelial cells (HUVECs) that expressed high nucleocapsid protein in response to either Mor or CAM-70 failed to express elevated ICAM-1, whereas some HUVECs that were incubated with Mor expressed high ICAM-1 prior to expression of MV nucleocapsid protein. Strain-specific differences in the ability of Mor and CAM-70 to induce ICAM-1 correlated with their ability to activate the latent transcription factor NF-kappaB. These studies suggest a preexisting component of MV particles that leads to strain-specific differences in the activation of NF-kappaB and the induction of ICAM-1 gene expression.
Asunto(s)
Endotelio Vascular/metabolismo , Molécula 1 de Adhesión Intercelular/metabolismo , Virus del Sarampión/metabolismo , Venas Umbilicales/metabolismo , Animales , Northern Blotting , Chlorocebus aethiops , Endotelio Vascular/citología , Ensayo de Inmunoadsorción Enzimática , Células Epiteliales/metabolismo , Células Epiteliales/virología , Técnica del Anticuerpo Fluorescente , Hemaglutininas Virales/metabolismo , Humanos , Virus del Sarampión/crecimiento & desarrollo , Glicoproteínas de Membrana/análisis , Glicoproteínas de Membrana/metabolismo , FN-kappa B/metabolismo , Proteínas de la Nucleocápside/metabolismo , ARN Mensajero/metabolismo , Venas Umbilicales/citología , Células Vero , Proteínas Virales/metabolismo , Vacunas Virales/farmacologíaRESUMEN
Fatal cases of filoviral infection are accompanied by a marked immunosuppression. Endothelial cells play a vital role in the host immune response through the expression of several immunomodulatory genes in addition to the expression of the antiviral genes, 2',5'-oligoadenylate synthetase [2'-5'(A)N], and the double-stranded RNA (dsRNA)-activated protein kinase (PKR). dsRNA, an intermediate generated during viral replication and gene transcription of many viruses, leads to the induction of immunomodulatory genes in endothelial cells. In this report, we show that induction of the major histocompatibility complex class I family of genes, 2'-5'(A)N, interleukin-6 (IL-6), PKR, interferon (IFN)-regulatory factor-1, and intercellular adhesion molecule-1 (ICAM-1) by dsRNA in human umbilical vein endothelial cells is suppressed by infection with the filovirus Ebola-Zaire (EZ). In contrast, induction of IL-6 and ICAM-1 by IL-1 is intact in EZ-infected cells. Gel shift analysis demonstrates that dsRNA-induced protein binding to IFN-responsive elements is strongly suppressed by EZ-IFN, whereas NF-kappa B activation by dsRNA remains intact. We previously reported that IFN signaling is suppressed by EZ infection, and these data strongly suggest that elements shared between IFN and dsRNA signaling are being inhibited by EZ. Inhibition of IFN and dsRNA responsiveness could play a role in the immunosuppression seen in EZ infections and would play a role in the pathogenesis of disease caused by EZ.