Part 3 of a 4-part series on viruses in animal production
All around the world, viruses are having an impact on humans and animals alike. When a virus infects an animal, it will impact the animal’s growth, performance and reproduction, and can even lead to death. Once a virus infects an animal, it is up to the immune system to start the process to kill the virus and remove it from the body.
Good nutrition, including trace mineral nutrition, plays an important role in preventing viral infections as well as improving the immune response if viruses do infect the animal.
Zinc, in particular, plays a key role in preventing virus replication, which is a critical component to a rapid and robust immune response to a viral infection.
When a virus gets into a body, it takes over the cells and starts to replicate and transmit to other cells. When the immune system detects the virus in the cells, it will start attacking the virus. If, at the same time, an animal’s body is able to impede the virus from replicating and spreading to other cells, the body will get the upper hand and be able to overcome the viral infection more rapidly.
Zinc works as an antiviral agent by preventing the replication of RNA viruses. It does this by inhibiting RNA-dependent RNA polymerase (RdRP), an enzyme that causes the replication of RNA viruses, like the coronavirus or many others that are known to affect livestock and poultry.
With COVID-19 there are many people who have become infected but do not develop the clinical disease. This is because their immune system responds more effectively to COVID-19, which includes inhibiting viral RdRP and stopping the virus from replicating before it gets out of control. This minimizes the infection without a lot of collateral damage to other cells in the body.
Additionally, zinc plays a role in modulating the interferon response. Interferon is a molecule that leads the immune response against viral infections. Zinc helps the body produce interferon when a virus is detected, and then dials down the immune response when the infection is cleared.
Zinc also plays a role in maintaining epithelial tissue and improving mucin production, which can help prevent viruses from entering an animal’s body in the first place. It helps improve the release of hydrochloric acid, which keeps the pH in the stomach low enough to keep bacteria and other pathogens from getting into the lower part of the gastrointestinal tract.
In addition to zinc, the trace minerals selenium, copper and manganese are required by the body and play a role in the adaptive and innate immune functions of animals.
Selenium is essential to activate the antioxidant enzyme, glutathione peroxidase (GPx). When reactive oxygen species (free radicals) outnumber antioxidants and lead to cell damage or tissue injury, this is known as oxidative stress. If there is a lot of oxidative stress, neutrophils – immune cells in an animal’s blood circulation– will be slower to leave the blood vessels and will take longer to clear an infection. A suboptimal selenium status results in lymphocytes – a type of white blood cell in the lymph nodes and the bloodstream that helps fight infection – being less effective in identifying antigens, bacteria and viruses, leading to a weaker immune response. By activating GPx, selenium helps reduce oxidative stress, thereby improving the function of neutrophils and lymphocytes.
Copper also helps relieve oxidative stress and improves T-cell proliferation. Helper T-cells help the body make antibodies, while killer T-cells directly kill cells that have been infected by a virus.
Manganese, along with zinc, plays a role in mucin production which, as mentioned earlier, helps prevent pathogens from entering the body in the first place. Research has also shown that manganese helps enhance the ability of the natural killer cells, which are a type of immune cell that kill cells infected with a virus.
Check back for the fourth and final installment of this series on viruses in animal production. The next article will take a closer look at zinc and how it improves the immune response to viral infections.