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1.
Mem Inst Oswaldo Cruz ; 102(2): 203-8, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17426886

RESUMO

Among the flaviviruses, dengue, with its four serotypes, has spread throughout the tropics. The most advanced vaccines developed so far include live attenuated viruses, which have been tested in humans but none has been licensed. Preclinical testing of dengue vaccine candidates is performed initially in mice and in nonhuman primates. In the latter the main criteria used to assay protection are neutralizing antibodies elicited by the vaccine candidate and the magnitude and duration of peripheral viremia upon challenge of previously immunized animals. Towards the identification of wild-type viruses that could be used in challenge experiments a total of 31 rhesus monkeys were inoculated subcutaneously of wild dengue types 1, 2, and 3 viruses. The viremia caused by the different viruses was variable but it was possible to identify dengue viruses useful as challenge strains.


Assuntos
Vírus da Dengue , Dengue/virologia , Viremia/virologia , Animais , Chlorocebus aethiops , Dengue/prevenção & controle , Vacinas contra Dengue/uso terapêutico , Vírus da Dengue/classificação , Vírus da Dengue/imunologia , Vírus da Dengue/patogenicidade , Modelos Animais de Doenças , Feminino , Humanos , Macaca mulatta/virologia , Masculino , Células Vero/virologia
2.
Mem. Inst. Oswaldo Cruz ; 102(2): 203-208, Mar. 2007.
Artigo em Inglês | LILACS | ID: lil-447559

RESUMO

Among the flaviviruses, dengue, with its four serotypes, has spread throughout the tropics. The most advanced vaccines developed so far include live attenuated viruses, which have been tested in humans but none has been licensed. Preclinical testing of dengue vaccine candidates is performed initially in mice and in nonhuman primates. In the latter the main criteria used to assay protection are neutralizing antibodies elicited by the vaccine candidate and the magnitude and duration of peripheral viremia upon challenge of previously immunized animals. Towards the identification of wild-type viruses that could be used in challenge experiments a total of 31 rhesus monkeys were inoculated subcutaneously of wild dengue types 1, 2, and 3 viruses. The viremia caused by the different viruses was variable but it was possible to identify dengue viruses useful as challenge strains.


Assuntos
Humanos , Animais , Masculino , Feminino , Vírus da Dengue/classificação , Vírus da Dengue/patogenicidade , Viremia/virologia , Chlorocebus aethiops , Modelos Animais de Doenças , Macaca mulatta/virologia , Células Vero/virologia
3.
Artigo em Inglês | MEDLINE | ID: mdl-10582318

RESUMO

Several amplicons with approximately 120 bp each, obtained from the upstream domain of Schistosoma mansoni female-specific gene F-10, were coupled to Dynabeads M-280 streptavidin. The beads were used as a matrix for affinity purification of nuclear proteins obtained from mixed populations of adult worms. A protein of approximately 12 kDa, bound to the DNA in a sequence-independent manner. In contrast, when the DNA matrix was narrowed down to smaller synthetic oligonucleotides, bearing sequences corresponding to the TATA box and the CAAT box, band-shift assays revealed that different nuclear proteins from either adult male or female worms formed complexes with the DNA adduct. In order to characterise the bound proteins, the same oligonucleotides were UV cross-linked to the male and female protein extracts. Whilst the band shift experiments showed that the proteins from each sex produced a distinct mobility pattern when the TATA box sequences were tested and a similar one when the CAAT box sequences were added to the proteins, UV cross-linking experiments revealed clear qualitative differences between both, male and female proteins and also between the proteins binding to the two motifs. These results are compatible with a model in which the differential expression of the F-10 gene might depend on individual sub-sets of proteins.


Assuntos
Proteínas de Ligação a DNA/genética , Schistosoma mansoni/genética , Animais , Sequência de Bases , Cromatografia de Afinidade , Proteínas do Ovo/genética , Eletroforese em Gel de Poliacrilamida , Feminino , Genes de Helmintos/genética , Proteínas de Helminto/genética , Masculino , Dados de Sequência Molecular , Proteínas Nucleares/metabolismo , Proteínas Nucleares/efeitos da radiação , Oligonucleotídeos/metabolismo , Oligonucleotídeos/efeitos da radiação , Oogênese/genética , Regiões Promotoras Genéticas/genética , Schistosoma mansoni/química , Raios Ultravioleta
4.
Mem Inst Oswaldo Cruz ; 90(2): 179-84, 1995.
Artigo em Inglês | MEDLINE | ID: mdl-8531654

RESUMO

Incubation of total protein extracts of Schistosoma mansoni with 3H 17-beta-estradiol and 20-hydroxyecdysone, revealed steroid binding proteins in both, male and female worms. The interaction of nuclear proteins with restriction fragments of the gender and stage-specific gene F-10 was investigated using the "Band-Shift" technique. Distinct male and female nuclear proteins bound to the fragments of this gene. Among the nuclear proteins, only those rich in cysteine residues bound to DNA. In vitro incubation of live worms with the estrogen antagonist Tamoxifen, altered the pattern of the DNA binding proteins, producing in females, a band profile similar to that obtained with male worm protein extracts. When Tamoxifen was injected into schistosome infected mice, the eggs produced by females presented an abnormal morphology, compatible with non-viable eggs. These results suggest that the regulation of transcription of the F-10 gene might involve steroid receptors.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas do Ovo/metabolismo , Proteínas de Helminto/metabolismo , Schistosoma mansoni/metabolismo , Animais , Cricetinae , Feminino , Genes de Helmintos , Masculino , Proteínas Nucleares/metabolismo , Ligação Proteica , Schistosoma mansoni/genética , Caracteres Sexuais
5.
Parasitology ; 110 ( Pt 2): 155-61, 1995 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-7885734

RESUMO

By incubating total protein extracts of Schistosoma mansoni with 3H-17-beta-estradiol and 20-hydroxyecdysone, steroid binding proteins were detected in both male and female worms. The interaction of nuclear proteins with a restriction fragment of the gender and stage-specific gene F-10 was investigated using the 'band-shift' technique. Male and female nuclear proteins bound in a distinct way to the fragment of this gene containing putative regulatory consensus motifs. Among the nuclear proteins, only those rich in cysteine residues bound to DNA. In vitro incubation of live worms with the oestrogen antagonist Tamoxifen, altered the pattern of the DNA binding proteins, producing in females a profile similar to that obtained with male worm protein extracts. This effect of Tamoxifen could not be correlated to inhibition of protein biosynthesis. These results suggest that the regulation of transcription of the F-10 gene might involve steroid receptors.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas do Ovo/metabolismo , Proteínas de Helminto/metabolismo , Schistosoma mansoni/metabolismo , Animais , Ecdisterona/metabolismo , Estradiol/metabolismo , Feminino , Regulação da Expressão Gênica , Genes de Helmintos/genética , Masculino , Proteínas Nucleares/metabolismo , Ligação Proteica , Receptores de Esteroides/metabolismo , Schistosoma mansoni/genética , Caracteres Sexuais , Tamoxifeno/metabolismo
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