Bovine tuberculosis (bTB), a disease of the cattle, has emerged as a global threat to livelihoods of farmers. The TB affects range of bovine species but cows and buffaloes have witnessed significant risk. Veterinarians and farmers consider the risk of spread of the disease among ranches a substantial concern. Those that test positive had to go slaughtering or culling to prevent the spread of this zoonotic TB. The causative agent is Mycobacterium bovis. In various parts of the world, farmers rear the cattle for dairy products and also meat. It thus becomes a matter of big public health to target bTB to prevent other foodborne diseases.
Old Vaccine Incompatible with Skin Test to Diagnose bTB in Cattle
Healthcare providers have seen Bacillus Calmette–Guérin (BCG) vaccine effective in preventing TB in humans. The BCG vaccine also works for cattle. But a fundamental dilemma is that it is incompatible with a popular TB skin test, PPD test that cattle in numerous countries undergo. Animal health surveillance use the test for detecting the infected cattle. However, those vaccinated by BCG also test positive for PPD test, making it difficult to distinguish the infected from non-infected cattle.
Researchers in the U.K. in a recent study revealed that they have been able to successfully developed a vaccine that is compatible with PPD. The journal Scientific Reports recently published the findings.
New Vaccine Expand Tools for Preventing Spread of TB in Cattle
The BCG vaccine contains a strain of Mycobacterium bovis, which defeats the purpose of investigating with PPD test. Hence, most healthcare systems around the world have banned the use of BCG among cows. However, researchers have been able to modify the BCG vaccine to filter out some of the proteins common with the pathogen Mycobacterium bovis. This was made possible by identifying the gene that encodes these immunogenic proteins. The researchers tested the efficacy of BCG vaccine without the encoded immunogenic proteins. They then used these deleted immunogenic proteins to make an effective skin test that is compatible with the new BCG vaccine. They demonstrates the success by testing the vaccine and test in guinea pigs.
This this strengthens the tool that can be used by farmers to detect TB in their cattle. The effective vaccination and the test will enable them to prevent the spread.