Novel 180- and 480-Base-Pair Insertions in African and African-American Strains of Helicobacter pylori

Abstract

Helicobacter pylori is a genetically diverse bacterial species that chronically infects human stomachs and sometimes causes severe gastroduodenal disease. Studies of polymorphic DNA sequences can suggest geographic origins of individual strains. Here, we describe a 180-bp insertion (ins180), which is just after the translation stop of a gene of unknown function, near the promoter of jhp0152-jhp0151 two-component signal transduction genes in strain J99, and absent from this site in strain 26695. This ins180 insertion was found in 9 of 9 Gambian (West African), 9 of 20 (45%) South African, and 9 of 40 (23%) Spanish strains but in only 2 of 20 (10%) North American strains and none of 20 Lithuanian, 20 Indian, and 20 Japanese strains. Four South African isolates that lacked ins180 and that belonged to an unusual outlier group contained a 480-bp insertion at this site (ins480), whereas none of 181 other strains screened contained ins480. In further tests 56% (10 of 18) of strains from African Americans but only 17% (3 of 18) of strains from Caucasian Americans carried ins180 (P < 0.05). Thus, the H. pylori strains of modern African Americans seem to retain traces of African roots, despite the multiple generations since their ancestors were taken from West Africa. Fragmentary ins180-like sequences were found at numerous sites in H. pylori genomes, always between genes. Such sequences might affect regulation of transcription and could facilitate genome rearrangement by homologous recombination. Apparent differences between African-American and Caucasian-American H. pylori gene pools may bear on our understanding of H. pylori transmission and disease outcome.

Neighborhood socio-economic characteristics, African ancestry, and Helicobacter pylori sero-prevalence

“…In fact, conservation of H. pylori genotype by race in the United States has been found before, and findings indicate that transmission occurs primarily through the family; thus, genotypes of the bacteria could be conserved through multiple human generations [35, 36]. In addition, the host genetics in families will be more similar.…”

Isolation and characterization of Helicobacter pylori recovered from gastric biopsies under anaerobic conditions

“…A PCR reaction amplified an intergenic region from the H. pylori genome as previously reported [25]. Based on the product size amplified, we could identify H. pylori strains of African origin by the distinctive 180bp insert that they carry in this intergenic region [25].…”

“…Based on the product size amplified, we could identify H. pylori strains of African origin by the distinctive 180bp insert that they carry in this intergenic region [25]. …”

Polymorphisms of the acid sensing histidine kinase gene arsS in Helicobacter pylori populations from anatomically distinct gastric sites

“…For each gastric population, 3 separate genomic DNA isolations were performed via CTAB extraction as previously described [20, 21]. Each DNA extraction was used in triplicate to amplify a ~300 base pair region encoding the 3′ end of arsS , including the homopolymeric cytosine tract, and part of the 5′ end of downstream gene hemB .…”