RT Journal Article SR Electronic T1 Predicting evolution using frequency-dependent selection in bacterial populations JF bioRxiv FD Cold Spring Harbor Laboratory SP 420315 DO 10.1101/420315 A1 Taj Azarian A1 Pamela P Martinez A1 Brian J Arnold A1 Lindsay R Grant A1 Jukka Corander A1 Christophe Fraser A1 Nicholas J Croucher A1 Laura L Hammitt A1 Raymond Reid A1 Mathuram Santosham A1 Robert C Weatherholtz A1 Stephen D Bentley A1 Katherine L O’Brien A1 Marc Lipsitch A1 William P Hanage YR 2020 UL http://biorxiv.org/content/early/2020/02/25/420315.abstract AB Predicting how pathogen populations will change over time is challenging. Such has been the case with Streptococcus pneumoniae, an important human pathogen, and the pneumococcal conjugate vaccines (PCVs), which target only a fraction of the strains in the population. Here, we use the frequencies of accessory genes to predict changes in the pneumococcal population after vaccination, hypothesizing that these frequencies reflect negative frequency-dependent selection (NFDS) on the gene products. We find that the standardized predicted fitness of a strain estimated by an NFDS-based model at the time the vaccine is introduced enables to predict whether the strain increases or decreases in prevalence following vaccination. Further, we are able to forecast the equilibrium post-vaccine population composition and assess the invasion capacity of emerging lineages. Overall, we provide a method for predicting the impact of an intervention on pneumococcal populations with potential application to other bacterial pathogens in which NFDS is a driving force.