6,500-year-old Salmonella enterica genomes link human-host adaptation to animal domestication
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Abstract
Salmonella enterica is a divers species of bacteria, many of which cause disease in humans and animals ranging from gastrointestinal infections to typhoid fever. It is hypothesized that the introduction of animal domestication in prehistoric times facilitated the emergence of human-adapted forms of this pathogen. By utilizing ancient DNA previous studies were able to identify the bacterium in a medieval European individual as well as in victims of a major sixteenth-century epidemic in Mexico. However, the diversity of Salmonella infecting humans in historic and prehistoric times is still largely unexplored.
Here we present eight S. enterica genomes recovered from up to 6,500-year-old human remains across Eurasia. Phylogenetic analysis revealed that all ancient Salmonella genomes are part of a previously uncharacterized super branch containing a variety of strains that are adapted to humans and other mammalian hosts. While Salmonella infections were also found in individuals with a foraging life style, the ancestral forms of strains adapted to humans today were only infecting individuals from groups who practiced animal domestication. Comparative genomic analysis shows variation in functional gene content suggesting that the prehistoric strains lacked host specificity. In addition, we describe convergent pseudogenization that is likely linked to host adaptation.
In summary, we present molecular evidence that links the emergence of human-adapted Salmonella to animal husbandry. Furthermore, by spanning a time interval of multiple millennia our data allows for insights into the genomic evolution of this clinically relevant human pathogen.
Here we present eight S. enterica genomes recovered from up to 6,500-year-old human remains across Eurasia. Phylogenetic analysis revealed that all ancient Salmonella genomes are part of a previously uncharacterized super branch containing a variety of strains that are adapted to humans and other mammalian hosts. While Salmonella infections were also found in individuals with a foraging life style, the ancestral forms of strains adapted to humans today were only infecting individuals from groups who practiced animal domestication. Comparative genomic analysis shows variation in functional gene content suggesting that the prehistoric strains lacked host specificity. In addition, we describe convergent pseudogenization that is likely linked to host adaptation.
In summary, we present molecular evidence that links the emergence of human-adapted Salmonella to animal husbandry. Furthermore, by spanning a time interval of multiple millennia our data allows for insights into the genomic evolution of this clinically relevant human pathogen.
Date Issued
2019-08
Publication Type
Conference Item
Language(s)
en
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