pylori and man co-evolution since the settlement of modern man (and H. pylori) in Asia, and posterior settlement in American land between 10,000 and 25,000 years ago, when a land bridge (the

Bering Strait) connected Siberia and Alaska during the last ice age [4]. The expression of M. HpyCH4III in African and American strains, but not in the Asian ones, suggests that this MTase was acquired later and that the corresponding strains gained access PS-341 purchase to America in a second wave of migration of African slaves [4]. It should be pointed out that most of the American strains analysed are from South and FG-4592 chemical structure Central American countries, which also experienced human traffic of African origin, although to a smaller extent when Elafibranor in vivo compared with other countries, such as Brazil. FokI’s resistance to cleavage, which in the present study associated with Asian and American strains, has been previously reported for American and Asian strains, but not

European and African [29], which is in agreement with the present study. Likewise, M. Hpy99I and M. Hpy188I associated with the American strains and were first isolated from the strains J99 and J188, also of American origin [18, 61]. Only M. HpyCH4III, which is associated with American strains and not with Asian strains in the present study, was first isolated from a Chinese strain [31]. However, only strains from Singapore where considered in the Asian group, which is a limitation of this study. Nine out of ten of the Singapore strains (strains id. 33, 35-37, 39, 40, 42-43, available at Helicobacter pylori MLST Databases [62]) were common with the study of Falush et al. After the sequence of eight genes (including vacA, which presents allelic diversity) the majority of these strains were assigned to the hspEastAsia subpopulation [5]. This is in accordance with present results, since both studies clearly isolate these strains. For European, American Atorvastatin and African strains, the dimension and diversity of these subgroups is higher, yielding more robust results. It is thought that intra-familiar transmission plays

a more important role in urban families than in rural families, where the horizontal transmission (for instance via non-parental caretakers) is predominant [63]. H. pylori appears to have established a long lasting colonization of its human host [64], probably being transmitted to subsequent human hosts by close human contact, e.g. between family or community members [63, 65], depending on the genetic and social-cultural habits of each population. Our study supports previous reports on the co-evolution of H. pylori and man, in the sense that H. pylori reflects human migrations [3], being transmitted among individuals who have close contact with each other, but are not necessarily family members. The biologic role of R-M systems is not completely understood. It remains an enigma if the increased number of MTases present in the H.