Diversity in immune systems can slow down or even prevent disease (pathogens) from spreading. We already know that diversity matters, for example in protecting crops and endangered wild populations from pathogens. However, it’s not entirely clear what drives this effect of diversity. It could be due to how diversity “dilutes” hosts, making them harder to infect; it could be because new pathogens are less likely to evolve when diversity is high; and it could be a combination of both.

To help answer why diversity matters for disease spread, we did an experiment with bacteria and their viruses. We found that diversity matters because the bacteria a virus can infect gets more diluted, which slows and eventually stops the virus. This effect also makes it harder for phage to evolve and infect new bacteria in the population. This is important because it gives us a better idea of how to limit diseases in already threatened populations.

Jack Common, SWBio DTP student

Paper: Diversity in CRISPR‐based immunity protects susceptible genotypes by restricting phage spread and evolution by Jack Common, David Walker‐Sünderhauf, Stineke van Houte and Edze R. Westra in Journal Of Evolutionary Biology.