Cell study aids TB vaccine insights

Insights into key immune cells in cattle could inform the development of vaccines against bovine tuberculosis.

Tests in cows have shown that numbers of natural killer (NK) cells – which are associated with a response to infection – are increased as a reaction to a tuberculosis (TB) vaccine.

The results, which confirm that vaccination with Bacille Calmette Guerin (BCG) stimulates production of this type of immune cell, could inform development of refined, effective vaccines for bovine TB, a disease that costs UK farmers £100m each year.

Scientists from the Roslin Institute studied the effect of administering BCG in calves that had been previously vaccinated or were given the vaccine for the first time. They compared the results with unvaccinated animals. 

In animals given the vaccine, tissue samples taken from lymph nodes located in the cows’ shoulder region a day or two after vaccination indicated a rise in NK cell numbers. This was found in cows given the vaccine for the first time and in animals receiving a repeat dose.

The outcomes help explain the biological processes that enable BCG to act as an effective vaccine against bovine TB and will inform ways to make vaccines more efficient and supportive of animal health.

The study team also looked signs of interactions between different immune cells types - such as changes in the NK cells’ location, clustering or aggregation. They did not find evidence of this, but further studies are under way to look at changes in the function of cells.

The study insights offer new understanding of the processes underlying effective BCG vaccination, and researchers hope to build on this by examining the spatial distribution of various immune cell types, to determine steps involved in driving protection from disease.

The study was published in Discovery Immunology.