Bubonic plague has a lasting effect on human immunity, according to a new study.
Researchers analyzed 36 remains of people who died from bubonic plague in 16th-century Germany and found the first evidence of an evolutionary adaptation to the disease. The team at the University of Colorado and the Max Planck Institute collected DNA samples from the deceased’s inner ear bones in a mass grave in the town of Ellwangene, southern Germany , where the plague raged.
They also took DNA samples from the city’s 50 current residents. This allowed scientists to compare the frequency spectrum – the distribution of genetic variants – among the dead and in the local population. Among the current living inhabitants, the researchers found evidence of the pathogen caused by Yersinia pestis, which causes DNA changes.
Lead author of the study, Dr Paul Norman, associate professor in the Department of Personalized Medicine at the University of Colorado School of Medicine, said: “We found that markers of innate immunity were increased. in the population of the population present in the city compared to the victims of the plague, suggesting that these spots may have evolved to resist the plague.
We suggest that these frequency changes could be due to exposure to the plague Y. pestis in the 16th century. This discovery is the first to show that Y. pestis can cause changes in the evolutionary process, shaping genes linked to immunity across generations.
According to the University of Colorado, since the bubonic plague raged across Europe for 5,000 years, researchers think: “Immune genes may have long been selected in the population, but were recently selected during epidemic events ”. The study, published in the journal Molecular Biology and Evolution, said: “Although the lethal potential of bubonic plague is very high if left untreated, it is still possible that specific individuals are protected by the plague: polymorphisms in the determinants of innate immunity.
In this case, any change in allele frequencies that occurred during a given epidemic crisis could turn out to be a genetic adaptation and is detectable in individuals today. This natural selection is likely to lead to frequency changes in DNA, according to the simulations. “
Dr Norman added: “I think this study shows that we can focus on these same gene families to examine immunity in modern pandemics. We know that these genes are largely involved in promoting resistance to infection. They highlight our own evolution. “
However, researchers don’t want people to get the wrong impression, especially when we’re in a pandemic like today. Dr Norman said: “I don’t want to encourage everyone to take the existing pandemic vaccine. But it’s a much safer bet than relying on your genes to save you.”
