Cheating and imperfect vaccines as drivers of bacterial evolution

Florian Lecorvaisier , Thomas Louis Philippe Martin

Cheating is an ubiquitous evolutionary strategy, appearing everywhere throughout the tree of life. Among bacteria, cheating appears mostly through the consumption of public good without participation in their production. Some vaccines, because they specifically target these public goods, may alter the eco-evolutionary dynamics of cheating in bacterial populations of pathogenic species such as Corynebacterium diphtheriae, the etiological agent of diphtheria, which produces a public virulence factor. We expand a series of fitness models to assess how the use of vaccines targeting a public good can impact the selective value of its production, alter the ecological dynamics between producers and non-producers, and select for novel phenotypes. Our results show that producers are counter-selected when a vaccine is used but only when the public good is non-mandatory for the growth and survival of the bacteria, and that the presence of non-producers facilitates the eradication of producers. These results advocate for comprehensive studies of the eco-evolutionary consequences of vaccines and illustrate how the competition between non-producers and producers can be useful in the eradication of public virulence factors producers.