Asunto(s)
Proteínas Bacterianas/inmunología , Proteínas de la Membrana/inmunología , Streptococcus agalactiae/inmunología , Antígenos Bacterianos/química , Antígenos Bacterianos/genética , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Clonación Molecular , Femenino , Genes Bacterianos , Humanos , Immunoblotting , Recién Nacido , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Embarazo , Infecciones Estreptocócicas/etiología , Infecciones Estreptocócicas/inmunología , Streptococcus agalactiae/genética , Streptococcus agalactiae/patogenicidad , Virulencia/genética , Virulencia/inmunologíaRESUMEN
The group B Streptococcus (GBS) causes the majority of life-threatening bacterial infections in newborn children. Most GBS strains isolated from such infections express a surface protein, designated Rib, that confers protective immunity and therefore is of interest for analysis of pathogenetic mechanisms. Sequence analysis demonstrated that Rib has an exceptionally long signal peptide (55 amino acid residues) and 12 repeats (79 amino acid residues each) that account for >80% of the sequence of the mature protein. The repeats are identical even at the DNA level, indicating that an efficient mechanism operates to maintain a highly repetitive structure in Rib. The structure of Rib is similar to that of alpha, a previously characterized surface protein that is common among GBS strains lacking Rib. However, highly purified preparations of Rib and alpha did not cross-react immunologically, although the two proteins show extensive amino acid residue identity (47% in the repeat region). When analyzed in Western blots, Rib and alpha give rise to a regularly spaced ladder pattern, apparently due to hydrolysis of acid-labile Asp-Pro bonds in the repeats. We conclude that Rib and alpha are members of a novel family of streptococcal surface proteins with unusual repetitive structure.
Asunto(s)
Antígenos Bacterianos , Proteínas de la Membrana Bacteriana Externa/química , Proteínas de la Membrana Bacteriana Externa/genética , Proteínas Bacterianas , Proteínas de la Membrana , Streptococcus agalactiae/genética , Secuencia de Aminoácidos , Proteínas de la Membrana Bacteriana Externa/inmunología , Secuencia de Bases , Clonación Molecular , Cartilla de ADN/genética , ADN Bacteriano/genética , Genes Bacterianos , Humanos , Inmunoquímica , Recién Nacido , Datos de Secuencia Molecular , Estructura Molecular , Peso Molecular , Reacción en Cadena de la Polimerasa , Señales de Clasificación de Proteína/química , Señales de Clasificación de Proteína/genética , Secuencias Repetitivas de Ácidos Nucleicos , Homología de Secuencia de Aminoácido , Infecciones Estreptocócicas/etiología , Streptococcus agalactiae/aislamiento & purificación , Streptococcus agalactiae/patogenicidadRESUMEN
cDNA fragments encoding the putative structural genes of the hepatitis C genome were isolated from a plasma pool of Japanese non-A, non-B hepatitis patients and from sera of individual Spanish patients. From the Japanese plasma pool a series of E1 clones was obtained that showed 88-98% homology among each other, both at the nucleotide and amino acid level. Compared to the sequences published by the Chiron Corporation and Takeuchi et al., the amino acid homology was 75-79% and 91-94%, respectively. Analysis of the core and E2/NS1 genes showed a high conservation of the core sequence and a high sequence variation in the 5' end of the E2/NS1 gene. The E1 gene of one Spanish isolate showed greater homology to the Chiron than to the Japanese sequence. Another Spanish isolate was more homologous to the Japanese sequence indicating that both hepatitis C genotypes are present in Europe. Analysis of the E1 gene of an isolate derived from a single patient with a 5-year interval revealed nine nucleotide and five amino acid changes.
Asunto(s)
Genes Virales , Hepacivirus/genética , Proteínas del Envoltorio Viral/genética , Proteínas Estructurales Virales/genética , Secuencia de Aminoácidos , Clonación Molecular , Genoma Viral , Hepacivirus/aislamiento & purificación , Humanos , Japón , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa/métodos , Mapeo Restrictivo , Homología de Secuencia de Ácido Nucleico , EspañaRESUMEN
A host/vector system suitable for large-scale production of HBsAg has been constructed and optimized in terms of the expression plasmid and yeast host strain in order to permit fermentation to very high cell densities. The final expression plasmid contains the coding sequence of the major HBsAg protein (P24) flanked by the promoter sequences from a glycolytic gene and by the transcription-termination region of the ARG3 gene. The host/vector system was found to be genetically stable under large-scale fermentation conditions as demonstrated by nucleotide sequencing and restriction mapping experiments. The P24 protein is recovered from yeast as particles whose physiochemical properties are very similar to those of plasma-derived HBsAg.