Early divergent strains of Yersinia pestis in Eurasia 5,000 years ago.
Bottom Line: How and when it originated remains contentious.We also identify a temporal sequence of genetic changes that lead to increased virulence and the emergence of the bubonic plague.Our results show that plague infection was endemic in the human populations of Eurasia at least 3,000 years before any historical recordings of pandemics.
Affiliation: Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Kemitorvet, Building 208, 2800 Kongens Lyngby, Denmark.Show MeSH
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Mentions: For the high-depth ancient Y. pestis genomes, we investigated the presence of 55 genes that have been associated with the virulence of Y. pestis (Figure 5A, Table S6). We found all virulence genes to be present, except the Yersinia murine toxin (ymt) gene that is located at 74.4–76.2 kb on the pMT1 plasmid (Figure 2C, arrow 1). The ymt gene encodes a phospholipase D that protects Y. pestis inside the flea gut, thus enabling this enteric bacteria to use an arthropod as vector; it further allows for higher titers of Y. pestis and higher transmission rates (Hinnebusch, 2005, Hinnebusch et al., 2002). When investigating all seven samples for the presence of ymt, we identified a 19 kb region (59–78 kb, Figure 2C arrow 2–3, Figure 5B) to be missing except in the youngest sample (RISE397, 951 cal BC) (Figure 5B, Table S7). We find this region to be present in all other published Y. pestis strains (modern and ancient), except three strains (5761, 945, and CA88) that are lacking the pMT1 plasmid completely.
Affiliation: Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Kemitorvet, Building 208, 2800 Kongens Lyngby, Denmark.