The Gut Microbiota Facilitates Drifts in the Genetic Diversity and Infectivity of Bacterial Viruses

Publication date: 13 December 2017
Source:Cell Host & Microbe, Volume 22, Issue 6
Author(s): Luisa De Sordi, Varun Khanna, Laurent Debarbieux
The intestinal microbiota and human health are intimately linked, but interactions between bacteria and bacteriophages in the context of the mammalian intestine remain largely unexplored. We used comparative population genomics to study a tripartite network consisting of a virulent bacteriophage, its bacterial host, and a phage-insensitive bacterial strain both in vitro and within the murine gut. The bacteriophage adapted to infect the insensitive strain when the three partners co-existed in the gut of conventional mice, but not in dixenic mice or in planktonic cultures. The molecular changes associated with modifications in the bacteriophage host spectrum included single amino acid substitutions and an unusual homologous intragenomic recombination event within the genome of the bacteriophage. An intermediate bacterial host isolated from the murine microbiota mediated bacteriophage adaptation. Our data indicate that by offering access to new hosts, the microbiota shifts the genetic diversity of bacteriophages, thereby promoting long-term persistence of bacteriophage populations.

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Teaser

The mechanisms underlying the dynamic co-evolution of bacteriophages and bacteria within the gut microbiota remain unclear. By coupling in vitro and animal experiments, De Sordi et al. show that the diverse bacterial community within the gut is an evolutionary force that promotes diversification of bacteriophage infectivity including host jumps.


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