Researchers who studied a strain of bacteria that is responsible for widespread epidemics in the global rabbit farming industry, have discovered just a simple genetic mutation is all that separates it from a strain that also infects humans.
The team – from the Universities of Glasgow and Edinburgh in Scotland – believes the discovery has major implications for how we assess the risks of bacterial diseases that can pass between humans and other animals.
The study – reported in Nature Genetics – suggests bacteria may be able to jump between host species more easily than we previously thought.
In their paper, the scientists describe how they traced the evolution of the bacterium Staphylococcus aureus ST121 in rabbits, where it can cause serious skin infections.
In humans, ST121 is found in the respiratory tract and on the skin of some people. It is usually harmless, but it can lead to a range of conditions – from minor infections to meningitis and sepsis.
In their study, the team found that rabbit-specific ST121 “evolved through a likely human-to-rabbit host jump over 40 years ago,” and that only a single, naturally occurring mutation was all that was required.
The team believes theirs is the first study to report a single mutation is sufficient to alter the host species of a pathogen during its evolution and to highlight the capacity for disease-causing microorganisms to “readily expand into new host species populations.”
Co-author Jose Penades, a professor in the Institute of Infection, Immunity and Inflammation at the University of Glasgow, adds:
“Our results represent a paradigm shift in understanding of the minimal adaptations required for a bacterium to overcome species barriers and establish in new host populations.”
Fellow co-author Ross Fitzgerald, a professor in the Centre for Infectious Diseases and of the Roslin Institute at the University of Edinburgh, says the finding has important implications that “will require a re-examination of the future threat posed by bacterial host-switching events.”
He notes that the potential seriousness of the finding is highlighted by the increasing opportunities for cross-species transmission in domestic, industrial and agricultural situations in a globalized world.
Meanwhile, Medical News Today recently learned of a study of mice that showed individuals can inherit bacterial DNA from their mothers in the womb. Writing in Nature, the researchers say influences on immunity and inflammation can also be passed to offspring through this mechanism.