RESUMO
One mechanism by which dengue (DEN) virus may cause cell death is apoptosis. In this study, we investigated whether the genetic determinants responsible for acquisition by DEN type 1 (DEN-1) virus of mouse neurovirulence interfere with the induction of apoptosis. Neurovirulent variant FGA/NA d1d was generated during the adaptation of the human isolate of DEN-1 virus strain FGA/89 to grow in newborn mouse brains and mosquito cells in vitro [Desprès, P. Frenkiel, M. -P. Ceccaldi, P.-E. Duarte Dos Santos, C. and Deubel, V. (1998) J. Virol., 72: 823-829]. Genetic determinants possibly responsible for mouse neurovirulence were studied by sequencing the entire genomes of both DEN-1 viruses. Three amino acid differences in the envelope E protein and one in the nonstructural NS3 protein were found. The cytotoxicity of the mouse-neurovirulent DEN-1 variant was studied in different target cells in vitro and compared with the parental strain. FGA/NA d1d was more pathogenic for mouse neuroblastoma cells and attenuated for human hepatoma cells. Changes in virus replicative functions and virus assembly may account, in a large part, for the differences in the induction of apoptosis. Our data suggest that identified amino acid substitutions in the envelope E protein and viral RNA helicase NS3 may influence DEN-1 virus pathogenicity by altering viral growth.
Assuntos
Apoptose , Vírus da Dengue/patogenicidade , RNA Helicases/química , RNA Helicases/metabolismo , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Chlorocebus aethiops , Culicidae , Vírus da Dengue/enzimologia , Vírus da Dengue/genética , Vírus da Dengue/crescimento & desenvolvimento , Células Epiteliais/patologia , Células Epiteliais/virologia , Glicoproteínas/metabolismo , Humanos , Cinética , Fusão de Membrana , Modelos Moleculares , Dados de Sequência Molecular , Mutação/genética , Neurônios/patologia , Neurônios/virologia , Conformação Proteica , Processamento de Proteína Pós-Traducional , RNA Helicases/genética , RNA Viral/biossíntese , Proteínas do Envelope Viral/genética , Proteínas Virais/biossíntese , Proteínas Virais/metabolismo , Virulência , Replicação ViralRESUMO
Yellow fever was presumably imported to the Americas from West-Africa from the 16th to the 19th century. American and African genotypes of the virus are distinguishable, indicating separate evolution in different vector/host cycles. The complete nucleotide sequence of the yellow fever virus strain TRINID79A, isolated in Trinidad in 1979, has been established. It exhibits extensive homology with those of current West-African strains and attenuated strain FNV. However, a unique deletion of the 3' non-coding region (NCR) of the viral RNA has been identified. It indicates that RYF1 and RYF2 repeated sequences of the 3' NCR are not necessary to the replication of the virus.
Assuntos
Genoma Viral , Filogenia , Vírus da Febre Amarela/genética , Regiões 3' não Traduzidas/genética , Sequência de Bases , DNA Complementar , Dados de Sequência Molecular , RNA Viral/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Trinidad e Tobago , Vírus da Febre Amarela/classificaçãoRESUMO
The first case of yellow fever in French Guiana since 1902 was reported in March 1998. The yellow fever virus genome was detected in postmortem liver biopsies by seminested polymerase chain reaction. Sequence analysis showed that this strain was most closely related to strains from Brazil and Ecuador.
Assuntos
Febre Amarela/epidemiologia , Vírus da Febre Amarela/genética , DNA Viral/análise , Evolução Fatal , Feminino , Guiana Francesa/epidemiologia , Humanos , Fígado/virologia , Filogenia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNA , Febre Amarela/virologia , Vírus da Febre Amarela/isolamento & purificaçãoRESUMO
Thousands of cases of dengue fever (DF) and several cases of dengue haemorrhagic fever were recorded in French Guiana during the recent outbreak of dengue-2 virus (1991-1992) and in subsequent years. One case with clinical signs typical of classical DF with neurological complications is reported in this study. The neurological features (encephalitis) appeared during the acute phase, 2 days after the onset of fever. Dengue-2 virus was detected in both the cerebrospinal fluid and blood sample. This case was fatal. This first reported case of classical DF with encephalitis in French Guiana is a new demonstration of the potential neurovirulence of dengue viruses.
Assuntos
Vírus da Dengue/isolamento & purificação , Dengue/virologia , Encefalite Viral/virologia , Aedes/virologia , Animais , Técnicas de Cultura de Células , Criança , DNA Viral/análise , Dengue/epidemiologia , Vírus da Dengue/genética , Encefalite Viral/epidemiologia , Evolução Fatal , Guiana Francesa/epidemiologia , Humanos , Insetos Vetores/virologia , Masculino , RNA Viral/sangue , RNA Viral/líquido cefalorraquidiano , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Dengue is a human disease which may be fatal in its hemorrhagic form. How dengue virus- and host-specified factors underlie virulence and pathogenesis is poorly understood. An immunological disorder is thought to be involved in dengue physiological symptoms. Whether the immune response is deleterious or beneficial to the host remains a matter of debate. In this review, we summarized developments in research on viral pathogenesis in the context of apoptosis triggered by dengue virus infection. Apoptosis, an active process of cell destruction, is one of the important consequences of dengue virus infection in vitro and in vivo. Dengue virus replication induces apoptosis in mouse neurons and human hepatocytes. The ability to activate this genetically programmed cell death pathway is dependent on both viral and cellular determinants.
Assuntos
Apoptose , Vírus da Dengue/patogenicidade , Dengue/patologia , Animais , Dengue/virologia , Vírus da Dengue/fisiologia , Humanos , Fígado/virologia , Replicação ViralRESUMO
In 1981, an epidemic of dengue hemorrhagic fever (DHF) caused by dengue-2 virus occurred in Cuba. This was the first DHF epidemic reported in the Western Hemisphere. In this study, we have analyzed four dengue-2 Cuban strains for two short genomic fragments: one on the envelope (E) glycoprotein and one at the E/nonstructural protein-1 (NS1) gene junction. The E segment of these 1981 Cuban isolates were more closely related to older dengue-2 virus strains such as New Guinea C 1944, Thailand 1964, Sri Lanka 1968, and Burma 1976 than to more recent isolates of this virus from Jamaica and Vietnam. More than 9% of the divergence with strains isolated from Jamaica and Vietnam was observed at the E/NS1 gene junction. One nucleotide change was observed between the first strain isolated during the epidemic and the rest of the Cuban strains. This mutation induced a nonconserved amino acid change from phenylalanine to leucine at position 43 that was not observed in any of the other strains with which it was compared.
Assuntos
Vírus da Dengue/genética , Dengue/virologia , Proteínas do Envelope Viral/genética , Proteínas não Estruturais Virais/genética , Sequência de Aminoácidos , Sequência de Bases , Pré-Escolar , Análise por Conglomerados , Cuba/epidemiologia , Primers do DNA/química , DNA Complementar/química , Dengue/epidemiologia , Vírus da Dengue/química , Vírus da Dengue/classificação , Surtos de Doenças , Feminino , Genes Virais , Genoma Viral , Humanos , Lactente , Leucina/química , Masculino , Dados de Sequência Molecular , Fenilalanina/química , Filogenia , Reação em Cadeia da Polimerase , RNA Viral/genética , Software , Proteínas do Envelope Viral/química , Proteínas não Estruturais Virais/químicaRESUMO
From July 1991 to October 1992, an outbreak of dengue spread into the main urban areas of French Guiana, where 90% of the country's 114,808 inhabitants live. In mid-July 1991 dengue-2 virus was identified as being responsible for most cases, while dengue-1 virus was rarely isolated and circulated at a low level. The number of dengue cases during this period was unknown because there was no clinically based dengue surveillance system. The only available data were for the number of suspected cases as indicated by the number of patients for whom blood samples were submitted to a laboratory for dengue diagnosis. Eight hundred forty-seven of the 2,948 suspected cases were diagnosed in the laboratory as dengue cases. Six fatal cases were reported. This outbreak was marked by the appearance of the first clinical cases of dengue hemorrhagic fever (DHF) in French Guiana. Forty cases met the World Health Organization definition of clinical DHF: 32 were grade II, seven were grade III, and one was grade IV and fatal. Eighteen cases were confirmed in the laboratory and 12 were probable; there was no proof of the dengue etiology for the remaining patients.
Assuntos
Dengue/epidemiologia , Surtos de Doenças , Anticorpos Antivirais/sangue , Sequência de Bases , Sequência Consenso , Primers do DNA/química , DNA Viral/química , Dengue/virologia , Vírus da Dengue/classificação , Vírus da Dengue/genética , Vírus da Dengue/imunologia , Guiana Francesa/epidemiologia , Testes de Inibição da Hemaglutinação , Humanos , Imunoglobulina M/sangue , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , RNA Viral/sangue , RNA Viral/genética , Estudos Retrospectivos , Sorotipagem , Transcrição GênicaRESUMO
The determination of amino acid changes in the envelope protein by direct sequencing of either genomic RNA or PCR-amplified cDNA fragments provides useful informations for assessing the genetic variability and the geographic distribution of the actually most widespread dengue-2 serotype. The possible link of variations in the envelope protein-gene and virus virulence is discussed.
Assuntos
Vírus da Dengue/genética , Dengue/microbiologia , Dengue/epidemiologia , Genótipo , HumanosRESUMO
The sequence of the 5'-end of the genome of dengue 2 (Jamaica genotype) virus has been previously reported (V. Deubel, R. M. Kinney, and D. W. Trent, 1986, Virology 155, 365-377). We have now cloned and sequenced the remaining 75% of the genomic RNA that encodes the nonstructural proteins. The complete genome is 10,723 bases in length with a single open reading frame extending from nucleotides 97 to 10,269 encoding 3391 amino acids. The 3'-noncoding extremity presents a stem- and loop-structure and contains a repeated oligonucleotide sequence. Comparisons of the nucleotide sequences of the genomes of dengue 2 viruses of different topotypes reveal 90-95% similarity, with 64-66% similarity evident between dengue viruses of different serotypes. The amino acid sequence of the polyprotein of dengue 2 Jamaica virus shows 97, 68, 50, and 44% similarity with those of other dengue 2, dengue 1, or dengue 4, West Nile, and yellow fever viruses, respectively. Despite amino acid sequence divergence, the hydrophobic profile of the flavivirus proteins is highly conserved. Proteins NS1, NS3, and NS5 are the most conserved. Conserved amino acid stretches present in all flavivirus proteins may be involved in common essential biological functions.
Assuntos
Vírus da Dengue/genética , Genes Virais , Sequência de Aminoácidos , Sequência de Bases , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Homologia de Sequência do Ácido NucleicoRESUMO
Four geographic variants (topotypes) of yellow fever (YF) virus from Africa and South America previously determined by RNA oligonucleotide mapping were analyzed for their structural, antigenic and virulence characteristics. The electrophoretic migration mobility and carbohydrate content of the envelope protein E characterized YF virus strains of South America. The NS 1 protein of South American and Central African YF virus strains was not precipitated by anti-NS 1 monoclonal antibodies (MAB) that precipitated NS 1 of West African strains. No distinction could be made among the YF virus strains on the basis of the neutralizing capacity of available MAB. South American, but not African YF virus strains were virulent for 8-day-old mice upon intraperitoneal inoculation. The results permitted characterization of topotypes of Central Africa and South America but failed to differentiate YF strains from West Africa.
Assuntos
Proteínas Virais/análise , Vírus da Febre Amarela/análise , África , Animais , Antígenos Virais/análise , Antígenos Virais/imunologia , Eletroforese em Gel de Poliacrilamida , Epitopos/imunologia , Camundongos , Peso Molecular , América do Sul , Proteínas do Envelope Viral/análise , Proteínas do Envelope Viral/imunologia , Proteínas não Estruturais Virais , Proteínas Virais/imunologia , Virulência , Vírus da Febre Amarela/imunologia , Vírus da Febre Amarela/patogenicidadeRESUMO
The nucleotide sequence of the 5'-terminal 2469 bases of dengue 2 (Jamaica genotype) virus has been determined and the encoded proteins compared with those of yellow fever and West Nile viruses, which belong to different flavivirus serogroups. The cDNA clone which was sequenced contains a 5'-noncoding region of 96 nucleotides followed by a single open reading frame coding for the structural proteins 5'-C-prM(M)-E-3' and the beginning of the NS1 nonstructural protein. The amino acid sequence homology between the structural polyprotein precursor of dengue 2 virus and those of yellow fever and West Nile viruses is 36.5 and 42%, respectively. The dengue virus structural proteins are similar in size and composition to those of the other flaviviruses. The basic capsid protein and the membrane and envelope proteins have hydrophobic regions at their C termini. The dengue 2 capsid C, membrane M, and envelope E proteins share 13, 36, and 43% homology, respectively, with the cognate proteins of yellow fever virus, and 33, 32, and 47% homology with the cognate proteins of West Nile virus. All 6 cysteine residues in the dengue 2 premembrane protein and all 12 cysteine residues in the dengue 2 envelope protein are conserved in the cognate proteins of yellow fever and West Nile viruses.
Assuntos
Vírus da Dengue/genética , Proteínas Virais/genética , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , Códon , DNA/genética , Vírus da Dengue/classificação , Flavivirus/genética , Conformação Proteica , SolubilidadeRESUMO
Isolates of yellow fever (YF) virus from Africa (Senegambia, Central African Republic, Ivory Coast, Burkina Faso) and from South America (Panama, Ecuador, Trinidad) were examined by oligonucleotide fingerprinting of the 40S genome RNA. Geographically isolated and epidemiologically unrelated viruses were very distinct. On the basis of the T1 oligonucleotide fingerprints of each isolate, four geographical variants (topotypes) of YF virus isolated within the same period of time have been established. The Ivory Coast and Burkina Faso topotypes were similar. In the Central African Republic, two variants could be found exhibiting 70 to 75% homology to one another. In South America, the three analysed strains exhibited only about 70% homology, but could be classified in the same topotype. The oligonucleotide fingerprints of the genome RNA offered a useful tool for the understanding of YF virus variability.