Evolution of defensive and pathogenic microbes in their host.

Defensive microbes that protect host organisms from pathogens are widespread in nature. To elucidate the consequences of microbe-mediated defence on pathogen virulence evolution, defensive and pathogenic microbes were co-passaged through a Caenorhabditis elegans host. Enterococcus faecalis were used in the host-protective role while Staphylococcus aureus were used as a virulent pathogen owing to their respective known properties.