Most Viruses Are Friendly and Beneficial to Us
Tags: Health, Fitness, Biotechnology, Life, Science

Most Viruses Are Friendly and Beneficial to Us

You have heard the bad, here’s the good

Photo by engin akyurt on Unsplash

Most viruses have a pathogenic relationship with their hosts. They invade the host cell, take over its cellular machinery and release new viral particles that will spread out and infect more cells and cause illness.

But they’re not all bad. Some viruses can actually kill bacteria, while others can fight against more dangerous viruses. So like protective bacteria (probiotics), we have several protective viruses in our body.

Bacteriophages

These types of viruses are found in the mucus membrane lining in the digestive, respiratory and reproductive tracts. Recent studies suggest that the phages present in the mucus are part of our natural immune system, protecting the human body from invading bacteria.

Phages have been used to treat dysentery, sepsis caused by Staphylococcus aureus, salmonella infections and skin infections for nearly a century. Early sources of phages for therapy included local water bodies, dirt, air, sewage and even body fluids from infected patients.

These days phages are genetically engineered. Individual strains of phages are tested against target bacteria, and the most effective strains are purified into a potent concentration.

How phages were discovered

Bacteriophages were discovered and named by Canadian-born doctor Felix d’Herelle while studying the feces of French soldiers suffering from dysentery in WWI.

By filtering the stool samples, d’Herelle was able to isolate the bacteria Shigella that caused the illness. And, he noticed that in some places, the Shigella was being destroyed by none other than an additional virus. After testing the virus on himself, he used it to treat his patients.

Despite this, the idea of injecting live viruses into patients made many doctors uncomfortable. By 1940, phages were superseded by antibiotics in the treatment of diseases. Today, phages have another important role in our world: as protectors of the water.

Every liter of seawater is home to about 100,000,000,000 viruses.

Add up all the liters of water in the ocean and that’s a whole lot of viruses! Luckily, marine phages make up part of this virus population. Phages destroy between 15 and 20% of nasty ocean bacteria each day, which prevents cholera and other harmful illnesses from spreading. Without phages, water-borne illnesses would wreak a lot more havoc.

Endogenous retroviruses

These viruses are generated within the bodies of animals, including humans. These viruses insert their genetic information into the DNA of the host. When the host’s cells divide, the DNA of the virus is also replicated, thus shaping our genes.

One important endogenous retrovirus is HERV-W, discovered in 1999 by Jen-LucBlond among others. One of the genes of this virus produces syncytin, a protein essential for the bonding of cells in the outer layer of the placenta. In other words, without this retrovirus, we wouldn’t be able to carry children. In this way, we can thank viruses for the survival of our species!

Latent (non-symptomatic) herpes viruses

Help human natural killer cells identify cancer cells and cells infected by other pathogenic viruses. They arm the natural killer cells with antigens (a foreign substance that can cause an immune response in the body) that will enable them to identify tumour cells.

This is both a survival tactic by the viruses to last longer within their host, and to get rid of competitive viruses to prevent them from damaging the host. In the future, modified versions of viruses like these could potentially be used to target cancer cells.