Scientists examining the remains of 36 bubonic plague victims from a 16th-century mass grave found evidence that evolutionary adaptive processes—driven by the organism—may have conferred immunity on later generations of people (Mol Biol Evol 2021 May 18. doi:10.1093/molbev/msab147).
“We found that innate immune markers increased in frequency in modern people from the town compared with plague victims,” said Paul Norman, PhD, an associate professor at the University of Colorado School of Medicine, Anschutz Medical Campus, in Aurora. “This suggests these markers might have evolved to resist the plague.”
The researchers collected DNA samples from bones of people in a mass grave in Ellwangen, Germany, which experienced plague outbreaks in the 16th and 17th centuries. They also took DNA samples from 50 current Ellwangen residents and compared their frequency spectra—the distribution of gene variants in a given sample—for a large panel of immunity-related genes.
Among the current inhabitants, the team found evidence that a pathogen, likely Yersinia pestis, prompted changes in the allele distribution for two innate pattern-recognition receptors and four human leukocyte antigen molecules, which initiate and direct immune response to infection.
“We propose that these frequency changes could have resulted from Y. pestis plague exposure during the 16th century,” Dr. Norman said.
The evolutionary processes, prompted by Y. pestis, may have been shaping certain human immunity-relevant genes in Ellwangen, and possibly throughout Europe, for generations and may offer some protection during the COVID-19 pandemic.
Later simulations showed that natural selection likely drove these allele frequency changes.
“I think this study shows that we can focus on these same families of genes in looking at immunity in modern pandemics,” Dr. Norman explained. “We know these genes were heavily involved in driving resistance to infections.”
Although these genetic changes might help provide some protection during this pandemic, Dr. Norman said, people should be vaccinated against COVID-19. “It’s a much safer bet than counting on your genes to save you.”
This article is from the June 2021 print issue.