Browsing by Author "Müller, I"

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    Cloning and comparison of ten gene sequences of a Chilean H-pylori strain with other H-pylori strains revealed higher variability for VacA and CagA virulence factors
    (2002) Müller, I; Medina-Selby, A; Palacios, JL; Martinez, P; Opazo, P; Bruce, E; Mancilla, M; Valenzuela, P; Yudelevich, A; Venegas, A
    We have cloned and sequenced ten Helicobacter pylori genes from a Chilean strain (CH-CTX1) including: a cytotoxin VacA fragment, a CagA fragment (A 17), 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 A] 7 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. A 17 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.
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    Complete sequence of the genome of the human isolate of Andes virus CHI-7913
    (2003) Tischler, ND; Fernández, J; Müller, I; Martínez, R; Galeno, H; Villagra, E; Mora, J; Ramírez, E; Rosemblatt, M; Valenzuela, PDT
    We report here the complete genomic sequence of the Chilean human isolate of Andes virus CHI-7913. The S, M. and L genome segment sequences of this isolate are 1,802, 3,641 and 6,466 bases in length, with an overall GC content of 38.7%. These genome segments code for a nucleocapsid protein of 428 amino acids, a glycoprotein precursor protein of 1,138 amino acids and a RNA-dependent RNA polymerase of 2,152 amino acids. In addition, the genome also has other ORFs coding for putative proteins of 34 to 103 amino acids. The encoded proteins have greater than 98% overall similarity with the proteins of Andes virus isolates AH-1 and Chile R123. Among other sequenced Hantavirus, CHI-7913 is more closely related to Sin Nombre virus, with an overall protein similarity of 92%. The characteristics of the encoded proteins of this isolate, such as hydrophobic domains, glycosylation sites, and conserved amino acid motifs shared with other Hantavirus and other members of the Bunyaviridae family, are identified and discussed.
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    Serological response to Helicobacter pylori recombinant antigens in Chilean infected patients with duodenal ulcer, non-ulcer dyspepsia and gastric cancer
    (1999) Opazo, P; Müller, I; Rollán, A; Valenzuela, P; Yudelevich, A; García-de la Guarda, R; Urra, S; Venegas, A
    We have previously cloned 10 Helicobacter pylori antigen genes from a Chilean strain including: cytotoxin VacA, a truncated region of CagA (called A17), a species-specific protein (Ag26), urease subunits (UreA, UreB), a flagellin, (FlaB), heat shock proteins (HspA and HspB), an adhesin (HpaA) and a lipoprotein (Lpp20). Immunogenicity of these antigens was tested by immunoblot with sera of Chilean infected patients, revealing that HpaA, A17, HspB and VacA were more frequently recognized (86%, 820/o, 68% and 68%, respectively). According to the clinical condition, it was determined that Lpp20 was preferentially recognized by sera from non-ulcer dyspepsia patients (80%), A17 and VacA by patients with duodenal ulcer (92% and 83% respectively), and HspB by patients with duodenal ulcer (83%) and gastric cancer (90%). An ELISA was developed with a purified mixture of A17 and VacA antigens to test the different groups of patients. It was found that sera from duodenal ulcer patients showed higher values than those from non-ulcer dyspepsia patients, but this difference was not significant (p<0.2). Moreover, sera from gastric cancer patients showed values lower than those from non-ulcer dyspepsia patients (p<0.019). These results indicate that, in the Chilean population, antibodies raised against VacA and A17 are not markers either for duodenal ulcer or for gastric cancer.