Article by Dr Kieran Meade, Associate Professor of Immunobiology and Conway Investigator, School of Agriculture and Food Science, UCD, Dublin.
Over 7 million cattle on the island of Ireland are currently busily converting lush green grass into protein to feed growing national and international markets.
As the old saying goes, ‘you are what you eat,’ but in addition to supporting our growth, our food plays a critical role in shaping our immune systems too.
Some studies have suggested that molecules in milk, including miniature RNAs (known as microRNAs), can pass from our digestive tract into our bloodstream and regulate our immune system .
Related studies have shown that exposure to animal antigens via contact with cows and consumption of dairy produce educates our immune system and reduces the incidence of allergy and asthma .
So cattle are much more than a source of nutrients for growth and have significantly contributed to mankind in many (udder) ways, which extend into biomedical science, immunology and medicine.
Two particularly topical contributions relate to vaccine discovery – both the very first vaccine for cowpox and the only existing vaccine for tuberculosis originated with cows.
It was Dr Edward Jenner who first acted on folklore describing the phenomenon that milkmaids who contracted the cowpox virus were subsequently protected from the more severe smallpox.
Both causal viruses are very similar, and so thanks to Blossom the cow, and a few human participants, the first vaccine was developed (‘vacca’ is latin for cow) in 1796.
As a direct result of this pioneering work, the World Health Authority announced the successful eradication of smallpox in 1980.
Like with the development of the smallpox vaccine, the original source organism for the Bacille Calmette-Guérin (BCG) vaccine was isolated from the udder of a cow.
This tuberculous cow was infected with the strain of mycobacteria which causes bovine tuberculosis, and after serial use, has been attenuated (weakened) so it can be safely used as a vaccine in humans.
Just over 100 years ago, the first BCG vaccine for TB was administered to patients and has since saved countless lives. Modifications to the same strain of bacteria continue today in efforts to produce a vaccine for use in cattle .
Cows playing their part against Covid-19
Fast forward 225 years from the birth of vaccinology, and cows are still playing their part – this time against Covid-19.
Antibodies are an important form of protection against infectious agents. Cow antibodies have a specific feature that makes them particularly useful as novel therapies for disease.
Known as knob domains, these independent mini-bodies are small in size and very stable making them ideal candidates for developing new treatments .
Biotechnology firms are now starting clinical trials to manufacture large quantities of these cow antibodies against Sars-CoV-2, which can then be purified and isolated as potential new treatments for Covid-19.
Due to the similarities between Sar-CoV-2 and coronaviruses in cattle, some authors suggest that drinking milk from hyperimmune cattle may be another route to protection against Covid-19 .
The production of pharmaceuticals from animals is known as pharming. Nature has a deep arsenal of weaponry honed over the course of evolutionary history that offers much promise for treating both current infections and the diseases of the future.
Many livestock species have hidden secrets that will be the subject of research for many years to come.
For references for this article and to learn more about our immunology research in livestock, see www.immunobiology.ie
- Perdijk, O., et al., Cow’s Milk and Immune Function in the Respiratory Tract: Potential Mechanisms. Front Immunol, 2018. 9: p. 143.
- Frei, R., et al., Exposure to nonmicrobial N-glycolylneuraminic acid protects farmers’ children against airway inflammation and colitis. J Allergy Clin Immunol, 2018. 141(1): p. 382-390 e7.
- Chandran, A., et al., Development of a diagnostic compatible BCG vaccine against Bovine tuberculosis. Sci Rep, 2019. 9(1): p. 17791.
- Macpherson, A., et al., Isolation of antigen-specific, disulphide-rich knob domain peptides from bovine antibodies. PLoS Biol, 2020. 18(9): p. e3000821.
- Arenas, A., et al., Bovine Coronavirus Immune Milk Against COVID-19. Front Immunol, 2021. 12: p. 637152.