Here’s How Black Death Affected Your Immune System

Here’s How Black Death Affected Your Immune System
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The bubonic plague, also known as the “Black Death,” was a pandemic that swept through Western Eurasia and North Africa between the years 1346 and 1353. It is estimated that between 75 and 200 million people lost their lives as a result of the pandemic, making it the worst epidemic in recorded human history. The plague was responsible for huge religious, societal, and economic changes, all of which had a considerable impact on the development of history in Europe.
New evidence has been revealed through research that suggests one of the most difficult times in known human history exerted a significant amount of selective pressure on the human population. This altered the frequency of specific immune-related genetic variations and has an effect on our vulnerability to disease in the present day.

In the span of fewer than five years, the Black Death was responsible for the deaths of as much as half of Europe’s population, making it the single deadliest epidemic in all of recorded history. New research has found evidence that one of the most difficult times in recorded human history exerted a significant selective pressure on the human population. This pressure altered the frequency of certain immune-related genetic variants and affected our susceptibility to disease in the present day.

The findings of the research, which were compiled by researchers from the University of Chicago (UChicago), McMaster University, and the Institut Pasteur, were presented in an article that was printed in the journal Nature on October 19th. The global pandemic of the black plague, which was caused by the bacterium Yersinia pestis (Y. pestis), wiped out between 30 and 60 percent of the population in cities across North Africa, Europe, and Asia. This had huge consequences for the human race, and it appears to have altered our genome.

What did the study find?

In the study, the researchers made use of current developments in sequencing technology to analyze ancient DNA samples extracted from the bones of more than 200 people from London and Denmark who passed away before, during, and after the Black Death plague raged across the region in the late 1340s. The plague was responsible for almost half of the deaths in the region during this time period. Through the use of targeted sequencing for a group of 300 immune-related genes, the researchers were able to identify four genes that, based on the mutation, either offered resistance to Y. pestis or raised the host’s vulnerability to it.

The research group focused their attention on a single gene known as ERAP2, which has a particularly robust connection to vulnerability. Individuals who held two copies of a certain genetic variant, known as rs2549794, were able to manufacture full-length copies of the ERAP2 transcript. As a result, these individuals were able to produce a greater quantity of the functional protein. This was in contrast to individuals who possessed a variant that led to a truncated and ineffective version of the transcript. The presence of a functional ERAP2 is necessary for the immune system to be able to recognize the presence of an infection.

The research group went to great lengths to investigate how the rs2549794 variant influenced the capacity of living human cells to aid in the fight against the plague. They came to the conclusion that macrophages that expressed two copies of the variant were superior to those that lacked it in terms of their ability to inhibit the growth of Y. pestis.

By investigating the impact of the ERAP2 variants in vitro, we are able to conduct a functional test to determine how the various ERAP2 variants alter the behavior of immune cells derived from modern people when they are confronted with living Yersinia pestis. The findings provide credence to the ancient DNA research which suggests that the rs2549794 variant is protective against the plague.

The scientists also came to the conclusion that the selection for rs2549794 is part of the balancing act that evolution does on our genome; although ERAP2 is defensive against the Black Death, in contemporary people, the same variant is linked to a higher vulnerability to autoimmune disorders, including serving as a recognized risk factor for Crohn’s disease.

The team wants to investigate gene mutations that affect sensitivity to bacteria in modern people and compare those to these old DNA samples in order to discover whether or not such gene changes were also the consequence of natural selection. Future study will scale the experiment to evaluate the entire genome, rather than just a selected group of immune-related genes.


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Anna is an avid blogger with an educational background in medicine and mental health. She is a generalist with many other interests including nutrition, women's health, astronomy and photography. In her free time from work and writing, Anna enjoys nature walks, reading, and listening to jazz and classical music.

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