Population Genetic Analyses of Helicobacter pylori Isolates from Gambian Adults and Children

Abstract

The gastric pathogen Helicobacter pylori is one of the most genetically diverse of bacterial species. Much of its diversity stems from frequent mutation and recombination, preferential transmission within families and local communities, and selection during persistent gastric mucosal infection. MLST of seven housekeeping genes had identified multiple distinct H. pylori populations, including three from Africa: hpNEAfrica, hpAfrica1 and hpAfrica2, which consists of three subpopulations (hspWAfrica, hspCAfrica and hspSAfrica). Most detailed H. pylori population analyses have used strains from non-African countries, despite Africa's high importance in the emergence and evolution of humans and their pathogens. Our concatenated sequences from seven H. pylori housekeeping genes from 44 Gambian patients (MLST) identified 42 distinct sequence types (or haplotypes), and no clustering with age or disease. STRUCTURE analysis of the sequence data indicated that Gambian H. pylori strains belong to the hspWAfrica subpopulation of hpAfrica1, in accord with Gambia's West African location. Despite Gambia's history of invasion and colonisation by Europeans and North Africans during the last millennium, no traces of Ancestral Europe1 (AE1) population carried by those people were found. Instead, admixture of 17% from Ancestral Europe2 (AE2) was detected in Gambian strains; this population predominates in Nilo-Saharan speakers of North-East Africa, and might have been derived from admixture of hpNEAfrica strains these people carried when they migrated across the Sahara during the Holocene humid period 6,000–9,000 years ago. Alternatively, shared AE2 ancestry might have resulted from shared ancestral polymorphisms already present in the common ancestor of sister populations hpAfrica1 and hpNEAfrica.

Genetic Diversity of Helicobacter pylori Strains Isolated from Patients with Gastroduodenal Diseases Using Multilocus Sequence Typing in Kermanshah

“…Of the 40 isolated strains, 38 new sequence types are present, and two pairs of isolates have the same sequence type. A study by Secka et al (35) in Gombian showed that four pairs of sequence types were the same. Given that a pair of sequence types in the present study, which has the same sequence sequences, were isolated in different days of the patients and processed in the lab, thus most likely they reflect the transmission of completely related strains by unrelated members of the community.…”

Helicobacter pylori Infection and Its Risk Factors: A Prospective Cross-Sectional Study in Resource-Limited Settings of Northwest Ethiopia

“…Children who regularly swim in rivers, streams, and pools drink stream water, or eat uncooked vegetables are more likely to be infected [ 47 ]. H. pylori have been cultured from diarrheal stools of children in Gambia, West Africa, where almost all inhabitants are infected by five years of age [ 48 ].…”

Genetic signatures for Helicobacter pylori strains of West African origin

“…These genome sequences were initially selected based on published MLST data or based on the geographic location where the strains were isolated (Europe or West Africa). Six of the 8 strains of West African origin were originally isolated in The Gambia, and previous MLST analyses showed that most strains isolated in the Gambia are classified as hspWAfrica, based on MLST analysis [ 54 ].…”