Genome-Wide Comparison of Medieval and Modern Mycobacterium leprae

Abstract

Leprosy: Ancient and Modern In medieval Europe, leprosy was greatly feared: Sufferers had to wear bells and were shunned and kept isolated from society. Although leprosy largely disappeared from Europe in the 16th century, elsewhere in the world almost a quarter of a million cases are still reported annually, despite the availability of effective drugs. Schuenemann et al. (p. 179 , published online 13 June; see the 14 June News story by Gibbons , p. 1278 ) probed the origins of leprosy bacilli by using a genomic capture-based approach on DNA obtained from skeletal remains from the 10th to 14th centuries. Because the unique mycolic acids of this mycobacterium protect its DNA, for one Danish sample over 100-fold, coverage of the genome was possible. Sequencing suggests a link between the middle-eastern and medieval European strains, which falls in line with social historical expectations that the returning expeditionary forces of antiquity originally spread the pathogen. Subsequently, Europeans took the bacterium westward to the Americas. Overall, ancient and modern strains remain remarkably similar, with no apparent loss of virulence genes, indicating it was most probably improvements in social conditions that led to leprosy's demise in Europe.

How old are bacterial pathogens?

“…Those analyses dated human infections in Israel to 9000 years ago [59] and tuberculosis of wild bison in North America to 17 000 years ago [60]. It has been suggested that aDNA from Mycobacterium is less exposed to DNA damage than that of other bacterial taxa, because mycobacterial cell walls contain mycolic acid [61]. This explanation could explain an unusually high success rate for the PCR amplification of aDNA from M. tuberculosis.…”

Plagued by doubt and viral misinformation: the need for evidence-based use of historical disease images

“…53 Similar work is commencing with leprosy. 54,55 Scientific evidence should nevertheless be historicised just as rigorously as other forms of historical evidence. 38,56,57 By confirming both the historical presence of pathogens and their evolution, scientific evidence has reinvigorated the humanist narrative of disease history.…”

Parallel detection of ancient pathogens via array-based DNA capture

“…Next generation sequencing as applied to ancient DNA has improved our understanding of the evolutionary history of pathogenic bacteria and the phylogeographic distribution of their associated diseases [1][2][3][4][5][6]. Thus far, most genomic analyses have relied on molecular capture techniques designed to target DNA from individual organisms suspected to have left molecular traces in preserved tissues.…”