RESUMEN
We have cloned and sequenced ten Helicobacter pylori genes from a Chilean strain (CH-CTX1) including: a cytotoxin VacA fragment, a CagA fragment (A17), a species-specific protein (TsaA), urease subunits (UreA, UreB), a flagellin subunit (FlaB), heat shock proteins (HspA and HspB), adhesin (HpaA) and a lipoprotein (Lpp20). We compared their deduced amino acid sequences with the corresponding sequences from three unrelated H. pylori strains, including fully sequenced strains 26695(UK) and J99(USA), and found that eight of them (UreA, UreB, FlaB, HspA, HspB, Lpp20, TsaA and HpaA) presented more than 97.3% identity. In contrast, VacA partial sequence showed lower identity values (93.2-94.9%). Moreover, we found major differences in the A17 region respect to the number and arrangement of the internal repeated elements when sequences from different strains were aligned. The A17 regions from strains CH-CTX1 and 26695 are very similar (91.8% identity) but lacked 6 repeated elements when compared to the Australian strains ATCC 43526 and NCTC 11637. The CCUG 17874 A17 region showed the largest deletion involving 9 repeats. A17 size differences between strains CCUG 17874 and CH-CTX1 were verified by PCR and polypeptide size. Such differences may explain variations in virulence among H. pylori strains as well as diversity in serum immunoreactivity.
Asunto(s)
Proteínas Bacterianas , Clonación Molecular , Variación Genética , Helicobacter pylori , Alelos , Secuencia de Aminoácidos , Secuencia de Bases , Western Blotting , Cartilla de ADN , Genes , Helicobacter pylori , Reacción en Cadena de la Polimerasa , VirulenciaRESUMEN
Mediante técnicas de ingeniería genética se ha logrado obtener líneas estables de células animales que sintetizan y secretan eficientemente partículas de antígeno de superficie del virus de la hepatitis B. Estas partículas presentan al microscopio electrónico un tamaño de 22 nm y son estructuralmente e inmunogénicamente similares a las obtenidas de plasma de enfermos crónicos, por lo que constituyen una excelente fuente de antígeno para la elaboración de una vacuna contra el virus