Biodiversity Research Seminar Series (BRS)
BRS Caroline Colijn: Balancing selection, strain replacement and vaccine design in the pneumococcus
November 6, 2024, 12:00 pm to 1:00 pm
A recording of the seminar can be found here:
Passcode: WQj&65.J
Host: Otto Lab
Speaker: Caroline Colijn
Title: Balancing selection, strain replacement and vaccine design in the pneumococcus
Abstract: Streptococcus pneumoniae, or “the pneumococcus”, is a bacteria that often resides in the respiratory tract without causing disease, but it may cause serious illnesses. Large-scale genomic studies have suggested that there is widespread negative frequency-dependent selection (NFDS); accessory genes (those not present in all isolates) occur at approximately the same frequencies in pre- and post-vaccine populations and in geographically separated populations, suggesting selection maintaining that variation. In this talk, I use models to explore how to design pneumococcal vaccines with the NFDS effect in mind, such that vaccines leave a more benign post-vaccine population of bacteria. We found that vaccines optimized for the pneumococcal populations found in the West are far from optimal for populations found in SE Asia. We also found that there are diminishing returns to adding more and more serotypes to conjugate vaccines.