Population genetic analysis of Helicobacter pylori by multilocus enzyme electrophoresis: extensive allelic diversity and recombinational population structure

Abstract

Genetic diversity and relationships in 74 Helicobacter pylori isolates recovered from patients assigned to distinct clinical categories were estimated by examination of allelic variation in six genes encoding metabolic housekeeping enzymes by multilocus enzyme electrophoresis. Seventy-three distinct allele profiles, representing multilocus chromosomal genotypes, were identified. All six loci were highly polymorphic, with an average of 11.2 alleles per locus. The mean genetic diversity in the sample was 0.735, a value that exceeds the level of diversity recorded in virtually all bacterial species studied by multilocus enzyme electrophoresis. A high frequency of occurrence of null alleles (lack of enzyme activity) was identified and warrants further investigation at the molecular level. Lack of linkage disequilibrium (nonrandom association of alleles over loci) indicates that horizontal transfer and recombination of metabolic enzyme genes have contributed to the generation of chromosomal diversity in H. pylori. In this sample of isolates, there was no statistically significant association of multilocus enzyme electrophoretic types or cluster of related chromosomal types and disease category.

Investigation of Association between oipA and iceA1/iceA2 Genotypes of Helicobacter pylori and Gastric Cancer in Iran

“…Several investigations have suggested that genetic diversity and substantial heterogeneity of H pylori has major contribution in pathogenesis of this bacterium, as each genotype leads to different type of diseases (Go et al, 1996;Marshall et al, 1996). For instance, cagA gene of H pylori is revealed to be involved in pathogenesis of Gastric cancer (Graham and Yamaoka, 1998;Zhang et al, 2013).…”

Immunoblotting for the serodiagnosis of Helicobacter pylori infection in Brazilian patients with and without gastric carcinoma

“…In addition, as the antibodies react with defined antigens, the test allows the simultaneous detection of bacterium virulence factors. However, as there is a high degree of genetic heterogeneity among H. pylori strains and, consequently, in the proteins that are surface-exposed or secreted (Go et al 1996, Herbrink & van Doorn 2000, the assay must be validated for the population being studied (Mitchell et al 1996, Aucher et al 1998, Yamaoka et al 1998, Figueiredo et al 2001.…”

Análise das impressões digitais de DNA e de fatores de virulência de linhagens de Helicobacter pylori

“…Isolados clínicos obtidos de diferentes pacientes têm mostrado grande diversidade genética (25,34) . Nesse sentido, estudos baseados nas seqüências genômicas de duas cepas de H. pylori (26695 e J99) revelaram que 22% dos genes não são essenciais e aproximadamente 6% são únicos a cada linhagem (7,50) .…”

“…Atualmente, o microrganismo é considerado o mais importante agente causador de gastrite, fator essencial na gênese da úlcera péptica e fator de risco para o desenvolvimento de câncer gástrico (19) . Há, ainda, evidências de sua associação com o linfoma MALT (linfoma do tecido linfóide associado à mucosa) e com o linfoma não-Hodgkin gástrico (15) .Isolados clínicos obtidos de diferentes pacientes têm mostrado grande diversidade genética (25,34) . Nesse sentido, estudos baseados nas seqüências genômicas de duas cepas de H. pylori (26695 e J99) revelaram que 22% dos genes não são essenciais e aproximadamente 6% são únicos a cada linhagem (7,50) .…”