A study analyzes the genomic blueprint of the louse-borne relapsing fever pathogen Borrelia recurrentis isolated from a 15th-century human skeleton in Scandinavia. Transmitted by body lice, B. recurrentis is a relapsing fever pathogen known to reach epidemic proportions. To determine how the ancient pathogen differs from current strains, Meriam Guellil, Nils Chr. Stenseth, Barbara Bramanti, and colleagues examined the pathogen's ancient DNA samples from a human skeleton excavated in Oslo, Norway. Using shotgun sequencing, the authors pieced together 98% of the pathogen's ancient genome. Comparing the DNA to that of strains currently circulating in Eastern Africa, the authors found that the ancient strain appears to have fewer genes for antigenic variation and retains the regulatory gene for oppA-1, a transporter protein degraded in modern strains. According to the authors, the findings reflect reductive evolution, a process in which specialized pathogens become increasingly adapted to a niche environment, increasing their ability to evade the host's immune system as well as their virulence. With the new genome placed in a distinct European branch, the detection of B. recurrentis underscores molecular aspects of medieval health not directly gleaned from the archeological record, according to the authors.
Article #18- 07266: "Genomic blueprint of a relapsing fever pathogen in 15th century Scandinavia," Meriam Guellil, et al.
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