Search results for "Base Sequence"
showing 10 items of 1146 documents
vacA Genotypes and Genetic Diversity in Clinical Isolates of Helicobacter pylori
1998
ABSTRACT Genetic diversity in Helicobacter pylori strains may affect the function and antigenicity of virulence factors associated with bacterial infection and, ultimately, disease outcome. In this study, DNA diversity of H. pylori isolates was examined by analysis of vacA genotypes and by restriction fragment length polymorphism (RFLP) analysis of H. pylori -associated genes ( vacA , cagA , flaA , ureAB , and ureCD ). Thirty-seven H. pylori isolates from 26 patients were successfully classified into distinct vacA allelic genotypes. The signal sequence allele s1 (31 of 37) predominated over the s2 allele (6 of 37) and was significantly associated with the occurrence (past or present) of gas…
Characterizations of adenovirus type 41 isolates from children with acute gastroenteritis in Japan, Vietnam, and Korea.
2004
ABSTRACT Genetic and antigenic characterizations of 70 strains of adenovirus type 41 (Ad41), isolated between 1998 and 2001 from children in Japan, Vietnam, and Korea, were done by DNA restriction enzyme (RE) analysis, sequencing analysis, and monoclonal antibody (MAb)-based enzyme-linked immunosorbent assay (ELISA). Eight genome types were observed in the present study, among which D25, D26, D27, and D28 were novel genome types. These eight genome types were divided into two genome-type clusters (GTCs) based on phylogenetic analysis of the hypervariable regions (HVRs) of the hexon. GTC1 includes D1, D25, D26, D27, and D28, and the GTC2 contains D4, D12, and D22. The amino acid homologies a…
Mutation rate of bacteriophage ΦX174 modified through changes in GATC sequence context
2011
Bacteriophage ΦX174 has a relatively high mutation rate of 10⁻⁶ substitutions per nucleotide per strand copying. A thirty-fold reduction in the mutation rate was achieved by introducing seven GATC sequences in its genome. This motif allows for methyl-directed mismatch repair and is strongly avoided in nature by ΦX174 and other phages.
Major histocompatibility complex class II binding site for streptococcal pyrogenic (erythrogenic) toxin A.
1994
Streptococcal pyrogenic exotoxin A (SPEA) is an important pathogenicity factor of group A streptococci. It is a member of the family of „superantigens” produced by Staphylococcus aureus and Streptococcus pyogenes and its T lymphocyte stimulating activity is involved into the pathogenesis of certain diseases caused by pyogenic streptococci. In this study we have produced and characterized recombinant SPEA molecules in Escherichia coli. These molecules are indistinguishable from natural SPEA in both T cell stimulatory and HLA class II binding activities. Human class II molecules are more efficient than mouse class II molecules in presenting SPEA to T cells. In binding tests to major histocomp…
Multidrug and broad-spectrum cephalosporin resistance among Salmonella enterica serotype enteritidis clinical isolates in southern Italy.
2002
ABSTRACT From 1992 to 1997, only six sporadic isolates of Salmonella enterica serotype Enteritidis from patients with cases of gastroenteritis in southern Italy exhibited resistance to broad-spectrum cephalosporins. Five isolates produced SHV-12, and one isolate encoded a class C β-lactamase. The bla SHV-12 gene was located in at least two different self-transferable plasmids, one of which also carried a novel class 1 integron.
Lineage diversification and recombination in type-4 human astroviruses.
2013
Abstract Human astroviruses (HAstVs) are important enteric pathogens and can be classified genetically and antigenically into eight types. During surveillance of HAstVs in Italy, type-4 HAstVs were detected only sporadically and found to cluster into two distinct genetic groups. Upon sequence analysis of the 3′ end of the polymerase gene (ORF1b) and of the full-length ORF2, the 2008 type-4 HAstV strains were characterised as a novel ORF2 genetic lineage, designated as 4c. The 2008 type-4 HAstVs also shared the ORF1b gene with similar HAstV-4c strains detected globally, thus displaying a conserved ORF1b/ORF2 asset. By interrogation of the databases, this novel lineage 4c accounted for 60.8% …
Systematics of Mepraia (Hemiptera-Reduviidae): cytogenetic and molecular variation.
2009
The haematophagous insects of the subfamily Triatominae (Hemiptera-Reduviidae) have great epidemiological importance as vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Mepraia was originally described as a monotypic genus comprised of Mepraia spinolai, distributed along coastal areas of northern Chile (from Region I to the Metropolitan Region). Recently, some M. spinolai populations have been ranked as a new species named Mepraia gajardoi. Several populations along the distribution range of the genus were sampled, and genetic differentiation was studied based upon the analysis of three molecular markers: cytogenetics (karyotype and chromosome behaviour during meiosis us…
Nuclear rDNA pseudogenes in Chagas disease vectors: Evolutionary implications of a new 5.8S+ITS-2 paralogous sequence marker in triatomines of North,…
2013
A pseudogene, paralogous to rDNA 5.8S and ITS-2, is described in Meccus dimidiata dimidiata, M. d. capitata, M. d. maculippenis, M. d. hegneri, M. sp. aff. dimidiata, M. p. phyllosoma, M. p. longipennis, M. p. pallidipennis, M. p. picturata, M. p. mazzottii, Triatoma mexicana, Triatoma nitida and Triatoma sanguisuga, covering North America, Central America and northern South America. Such a nuclear rDNA pseudogene is very rare. In the 5.8S gene, criteria for pseudogene identification included length variability, lower GC content, mutations regarding the functional uniform sequence, and relatively high base substitutions in evolutionary conserved sites. At ITS-2 level, criteria were the shor…
Identifying four Trypanosoma cruzi I isolate haplotypes from different geographic regions in Colombia
2007
Abstract Trypanosoma cruzi has been classified into the groups T. cruzi I and T. cruzi II. The latter is subdivided into five smaller lineages based on multilocus enzyme electrophoresis and random amplified polymorphic DNA, designated as IIa-IIe, which shows correspondence with rRNA/mini-exon lineages. Twelve previously characterised T. cruzi isolates from different hosts, including humans, Didelphis marsupialis, and triatomines were analysed to establish genetic variability in T. cruzi group T. cruzi I isolates from different geographical regions of Colombia. DNA samples were sequenced based on the mini-exon gene intergenic region. Sequences were analysed using Clustal W, Staden 1.5 and ME…
Identification of Shigella sonnei biotype g isolates carrying class 2 integrons in Italy in 2001-2003
2005
ABSTRACT Phenotyping and genotyping have been carried out on 64 epidemic and sporadic isolates of Shigella sonnei identified in Italy in the years 2001 to 2003. Class 2 integron carriage has been also investigated. Isolates from four of the five outbreaks and four of six sporadic cases were biotype g , pulsed-field gel electrophoresis type B, and class 2 integron positive, suggesting emergence and spread of an epidemic clone in Italy.