Evolution of an equine plague
Much of our research is aimed at discovering how S. equi evolved to cause such a widespread and devastating disease in horses.
S. equi shares 96% DNA identity with the common horse bacterium Streptococcus zooepidemicus, which is an opportunistic pathogen linked to respiratory disease, keratitis, abortion and wound infections.
We have compared the DNA genetic codes of these related bacteria to identify 60 pieces of DNA (genes) that may have contributed to the aggressive nature of S. equi. This has enabled us to focus on these key genes for the development of new vaccines and diagnostic tests.
Comparison of the S. equi (bottom) and S. zooepidemicus (top) DNA sequences to identify ‘white’ areas that are unique to S. equi or S. zooepidemicus and whose gain or loss, respectively, may have contributed to the evolution of S. equi.
Our research has identified different types of S. equi circulating the world, so that we can ensure that our vaccines and diagnostic tests can be applied where ever they are needed. This work in conjunction with Dr. Keith Jolley of the University of Oxford has enabled us to draw ‘family trees’, which show a geographical bias in the strains infecting horses in Europe compared with the USA and Japan.
The global grip of strangles. It will be important that our new vaccines and diagnostics can be used to combat this disease throughout the world.
