Els has taken a really interesting look this month at the news surrounding a new PCR test available to aid large animal vets in their important work.
New PCR Test available for bovine mycoplasma
Els de Vrijer (Vet News Farm Animal Editor)
Bovine mycoplasma is a bacterial infection that is responsible for several diseases in the cow. Although it mainly causes respiratory disease, it can also be responsible for abortions, mastitis and arthritis. Clearly, this leads to huge economical losses within the dairy industry: €500 million per year in the European dairy industry alone. The disease is a tricky one to conquer. It is hard to diagnose due to its inconsistent gene expression and varying response to treatment. M. bovis is also very similar to another bacterium, m. agalactiae, varying by only 8 nucleotides in its genetic makeup. It is also incredibly slow and difficult to culture, and treatment with antibiotics is not cost-effective. Therefore, the main means of controlling the disease lies with prevention. Recently, a new PCR test for m. bovis has become available, making the future for the control of the disease much brighter.
PCR testing is a method of copying fragments of DNA, which can then be used to locate the presence of a pathogen in an organism. Firstly, the DNA strand is separated using a thermocycler at a high temperature. The mixture is then cooled and sequences of nucleotides that have complementary bases to each end of the DNA fragment that needs to be copied, called ‘primers’ are attached. These provide a starting sequence for the copying of DNA. Then, the temperature is increased to around 72°C to provide the optimum temperature for DNA polymerase to work at. This adds other nucleotides to the DNA sequence, thereby copying the DNA. In a short amount of time, several copies of the DNA can be made. These can then be compared to the DNA of the bacterium to see whether it is present. It is a rapid and efficient method of pin pointing the disease – this particular test takes only 2.5 hours before the results are ready. “The improved sensitivity of this new test means that veterinarians will be able to monitor dairy herds for sub-clinical infection using samples from the bulk tank,” said Eric Sellal, Head of Animal Health EMEA at Life Technologies.The scientists have improved upon the previous test by locating a new target gene on the mycoplasma bovis genome, which is clearer to locate.
Hopefully, this new test will provide veterinarians with a tool for quickly locating this pathogen and preventing its rapid spread throughout the herd.
AQA Biology A2 textbook – Glen Toole and Susan Toole (Nelson Thornes)