Exploring the Potential of a Unique Set of Antibodies to Treat Strangles in Horses

SUMMARY: Researchers will explore the use of unique antibodies called “nanobodies” to treat strangles, a common but severe airway infection of horses.

THE PROBLEM: Strangles is a common, highly contagious airway infection in horses that leads to abscesses in lymph nodes of the throat and head. This causes pain and difficulty breathing or eating, and results in high treatment cost and animal suffering. Once horses show signs there are few treatment options, except allowing horses to recover in quarantine for many weeks until the abscesses drain. Since treatment is limited and the time for recovery is long, the key is to prevent disease and minimize its spread during outbreaks. However, strangles vaccines take weeks to work, are often not effective, and can have side effects. New treatment options could improve recovery times and prevent disease spread. Treatment with antibodies that bind bacteria may offer a new solution, which has already helped to prevent similar ailments in people. The team proposes using a similar approach to avoid strangles infection in horses.

THE PROJECT: Alpacas make unique antibodies, called “nanobodies” (VHHs), that are very small and robust. This makes them much easier and cheaper to produce than the typical antibodies from other species. Horses are infected by strangles in the upper airways. An inhaled drug that binds bacteria would be ideal to reduce infection risk. Since VHHs are hardy, they can be directly delivered into the airways by a nebulizer. The team’s goal is to vaccinate alpacas with two proteins from the surface of the bacteria which cause strangles (Streptococcus equi equi). The team will then isolate antibodies that block the functions of these proteins and will test how well they work to prevent growth of bacteria, avoid damage to airway cells, and prevent bacteria from avoiding the immune system.

POTENTIAL IMPACT: This study will provide important information about using this new technology to prevent strangles. It will also lay the path for future studies to directly deliver these antibodies to the nose and throat in horses and protect them from infection. It is the first use of this new technology in horses and leads the way for further application to both animals and people.