AUTHOR=Mendoza-Elizalde Sandra , Arteaga-Resendiz Nancy K. , Valencia-Mayoral Pedro , Luna Raúl C. , Moreno-Espinosa Sarbelio , Arenas-Huertero Francisco , Zúñiga Gerardo , Velázquez-Guadarrama Norma 

TITLE=Diversification of the vacAs1m1 and vacAs2m2 Strains of Helicobacter pylori in Meriones unguiculatus

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.01758

DOI=10.3389/fmicb.2016.01758

ISSN=1664-302X

ABSTRACT=<p>The bacterium <italic>Helicobacter pylori</italic> exhibits great genetic diversity, and the pathogenic roles of its virulence factors have been widely studied. However, the evolutionary dynamics of <italic>H. pylori</italic> strains during stomach colonization are not well-characterized. Here, we analyzed the microevolutionary dynamics of the toxigenic strain <italic>vacAs1m1</italic>, the non-toxigenic strain <italic>vacAs2m2</italic>, and a combination of both strains in an animal model over time. <italic>Meriones unguiculatus</italic> were inoculated with the following bacteria: group 1-toxigenic strain <italic>vacAs1m1/cagA+/cagE+/babA2+</italic>; ST181, group 2-non-toxigenic strain <italic>vacAs2m2/cagA+/cagE+/babA2+</italic>; ST2901, and group 3-both strains. The gerbils were euthanized at different time points (3, 6, 12, and 18 months). In group 1, genetic alterations were observed at 6 and 12 months. With the combination of both strains, group 3 also exhibited genetic alterations at 3 and 18 months; moreover, a chimera, <italic>vacA m1-m2</italic>, was detected. Additionally, four new sequence types (STs) were reported in the PubMLST database for <italic>H. pylori</italic>. Synonymous and non-synonymous mutations were analyzed and associated with alterations in amino acids. Microevolutionary analysis of the STs (PHYLOViZ) identified in each group revealed many mutational changes in the toxigenic (<italic>vacAs1m1</italic>) and non-toxigenic (<italic>vacAs2m2</italic>) strains. Phylogenetic assessments (eBURST) did not reveal clonal complexes. Our findings indicate that the toxigenic strain, <italic>vacAs1m1</italic>, and a combination of toxigenic and non-toxigenic strains acquired genetic material by recombination. The allelic combination, <italic>vacAs2m1</italic>, displayed the best adaptation in the animal model over time, and a chimera, <italic>m1-m2</italic>, was also identified, which confirmed previous reports.</p>