Metagenomic analysis of a blood stain from the French revolutionary Jean-Paul Marat (1743-1793), Hacker News

The French revolutionary Jean-Paul Marat was assassinated in 1793 in his bathtub, where he was trying to find relief from the debilitating skin disease he was suffering from. At the time of his death, Marat was annotating newspapers, which got stained with his blood and were subsequently preserved by his sister. We extracted and sequenced DNA from the blood stain and also from another section of the newspaper, which we used for comparison. Analysis of human DNA sequences supported the heterogeneous ancestry of Marat, with his mother being of French origin and his father born in Sardinia, although bearing more affinities to mainland Italy or Spain. Metagenomic analyzes of the non-human reads uncovered the presence of fungal, bacterial and low levels of viral DNA. Relying on the presence / absence of microbial species in the samples, we could confidently rule out several putative infectious agents that had been previously hypothesised as the cause of his condition. Conversely, some of the detected species are uncommon as environmental contaminants and may represent plausible infective agents. Based on all the available evidence, we hypothesize that Marat may have suffered from a primary fungal infection (seborrheic dermatitis), superinfected with bacterial opportunistic pathogens.

SignificanceThe advent of second-generation sequencing technologies allows for the retrieval of ancient genomes from long-dead people and, using non-human sequencing reads, of the pathogens that infected them. In this work we combined both approaches to gain insights into the ancestry and health of the controversial French revolutionary leader and physicist Jean-Paul Marat (1743 – 1793). Specifically, we investigate the pathogens, which may have been the cause of the debilitating skin condition that was affecting him, by analysing DNA obtained from a paper stained with his blood at the time of his death. This allowed us to confidently rule out several conditions that have been put forward. To our knowledge, this represents the oldest successful retrieval of genetic material from cellulose paper.