Equine Research Could Keep Humans From Getting Hoarse
A new research technique developed to investigate strangles in horses has helped scientists in human medicine take a leap forward in understanding the bacteria that causes many of us to become hoarse ourselves.

Scientists at the Houston Methodist Research Institute, in Texas, in partnership with scientific and veterinary research charity the Animal Health Trust (AHT), based in Newmarket, U.K., have identified new genes linked to how Streptococcus pyogenes, the infection responsible for a sore throat, survives in human saliva. The technique they used to support this discovery was developed by the AHT to better understand Streptococcus equi, which causes strangles in horses.

With an estimated 600 outbreaks of strangles each year in the U.K. alone, the AHT has spent many years examining how the bug causes disease, to aid in effective vaccine development. To do this, AHT scientists constructed a new method for identifying the most important genes for the bug’s survival in different conditions. They shared this technique with their human medicine counterparts to enable them to analyse the human pathogen. This example of the transfer of knowledge between veterinary and human research under the umbrella of ‘One Medicine’ has huge potential to enhance scientific knowledge to the benefit of both animals and humans.

“We are delighted that a technique developed at the AHT to learn more about Streptococcus equi and strangles in horses has provided new results that could benefit people, too,” said Andrew Waller, BSc, PhD, head of bacteriology at the AHT. “We have learnt a huge amount about our bug through following the work being done on human diseases, and it is great to be able to give something back in return. This study highlights the similarities of animal and human pathogens. We hope that our technique will also prove useful for the study and prevention of other diseases, regardless of the animal they affect.”

Humans at risk

The number of cases of Streptococcus pyogenes infections around the world has increased dramatically over the past 20 years; this bug is responsible for 600 million cases of pharyngitis (a sore throat) in people each year. The bacteria is also responsible for a further 100 million cases of invasive disease including scarlet fever, acute rheumatic fever, and the flesh-eating disease necrotising fasciitis, the onset of which often follows on from initial cases of pharyngitis. However, despite the cost to human health, relatively little is known about which of the approximately 1,800 genes in Streptococcus pyogenes are required for it to infect people, and persist in their throats.

Helped by horses

The process of unravelling the disease-causing processes of bacteria has traditionally needed to be carried out one gene at a time. However, the AHT’s method enables the importance of every gene in the bug to be tested at once. It allowed the Houston scientists to identify 92 genes needed by Streptococcus pyogenes to grow in human saliva in the lab, replicating the critical first stage required on the path it uses to cause disease in people.

“The ability to establish the importance of every gene in Streptococcus pyogenes within one experiment has the potential to accelerate research into this important human pathogen” explained James Musser, MD, PhD, professor of pathology and genome medicine at the Houston Methodist Research Institute. “In follow on tests, we were immediately able to confirm that six of these new genes really did affect growth in human saliva, suggesting that this new information has exciting potential for developing novel therapeutics and vaccines with which to improve human health.”

The study, “Novel Genes Required for the Fitness of Streptococcus pyogenes in Human Saliva,” was published in mSphere.