Dangerous foal bacteria laid bare, vaccine on way

Rhodococcus equi can cause a lethal form of equine pneumonia in foals.
Rhodococcus equi can cause a lethal form of equine pneumonia in foals.

The genetic blueprint of a bacterium that can kill foals is paving the way to a vaccine.

Rhodococcus equi can cause a lethal form of equine pneumonia in foals.

Despite the seriousness of the disease known as “rattles”, there has been no vaccine available.

Rhodococcus equi is one of the most important causes of illness in foals between one and six months old, particularly if they don’t have much resistance.

Dr John Prescott, professor and chairman of the Ontario’s Veterinary College’s Department of Pathobiology at the University of Guelph, in Canada, has been unwavering in a three-decade pursuit of a vaccine.

The advent of genomic research has opened up fresh opportunities to develop a suitable vehicle. The recent mapping of its genome, published in 2010, holds out the promise of a vaccine in the near future.

R. equi is able to stow away inside a young foal undetected for months.

By the time symptoms of panting and coughing first appear, the only course of action is the expensive and time-consuming administration of antibiotics.

Rhodococcus equi loves hot dusty environments and lurks in soil and manure.Early warning signs for Rhodococcus include:

  • Coughing or panting
  • The young foal may go off its feed or stop suckling

Preventative Measures include avoiding:

  • Turn out in sandy environments
  • Overcrowding paddocks

Early administration of antibiotics is the only treatment available at present.

Prescott and his team are collaborating internationally to tackle this global disease. Prescott’s former MSc student, Iain MacArthur, is also committed to the development of a vaccine.

MacArthur is currently working on his doctorate at the University of Edinburgh and runs tests using micro-arrays. This entails printing every Rhodococcus gene onto a slide and looking at their expressions under different conditions.

MacArthur explains the advantages of having the blueprint for the R. equi genome: “Instead of hunting around a cave with a tiny flashlight, we can now switch the lights on, view all contents and see how the genetic material relates.”

Prescott says: “This level of understanding would have been considered almost science fiction just a few years ago. It is incredible what we can do with this new genomic technology.

“The advances in research, since 2003 when the human genome project mapped out all the sequence of DNA in the body, have been truly incredible. When looking at all 5000 genes in the R. equi sequence they are now able to assign a function to each – a task which simply was not possible before mapping the R. equi genome.

“The level of understanding has been increased exponentially due to advances allowing researchers to look at the whole genomic picture.

“It’s a very complex process, although it gets easier as more and more people work in the area of genomics.”

Researchers are now able see all the genes that are switched on – the complete blueprint. They now know what makes this organism a pathogen, what it needs to live and how it works.

Prescott and MacArthur are isolating and targeting the most switched on and linked genes to develop a weakened form of the live virulent which could then be orally administered as a vaccine.

They predict that a vaccine is not far away.

Reporting: Jackie Bellamy

Dr Prescott’s website:
Dr Prescott’s background: http://www.equineguelph.ca/research/researcher.php?profile=Prescott



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