Humans Would Likely Be Non-Existent Without These Viruses

Mini-scientists and engineers responsible for human evolution

Photo by Alekon pictures on Unsplash

Imagine a lizard giving birth in the Maternity section of the hospital.

We are no strangers to lizards. But a lizard giving birth rather than laying eggs is a strange fete to witness. Our primary knowledge about reptiles is that they are egg-laying vertebrates. An exception to the rule is the Mabuya lizards.

These lizards have a special type of placenta wildly similar to the mammalian ones. It is a misfit in the basket of reptiles as far as this biological process goes. But mammals too have their extreme versions — the egg-laying ones. Despite their extreme reproductive behaviour, we were taught about this special group. The ones we weren’t taught about were this category of lizards.

It’s difficult to box misfits. They continue to persist despite man’s inclination to silo diversity into categories. In the same wavelength, it’s difficult to merge the word viruses with survival. The COVID-19 pandemic took many lives of loved ones. Viruses should be lethal.

It’s a mistaken interpretation. In reality, we would not have made it this far without viruses. It’s the same virus responsible for the unique reproductive process of the Mabuya lizards.

Humans need viruses to have successful births

After the sperm and the ovum fuse, the product moves toward the centre of the uterus to implant. It should take less than seven days.

The outer cover of this fused cell is made up of a thin layer that feeds and protects the growing cell. This outer shell is called the trophoblast. The word ’troph’ means to feed. Blast is a common term used for immature cells. Thus, the name trophoblast is a fitting one.

The mystery begins, however, when this layer divides into two: an inner layer that continues to protect and regulate the internal environment of the cell and an outer one that changes form into a fused gel of cells.

This fusion is mediated by a mini-scientist — a virus.

The virus is touted to have incorporated itself into our genome to serve this exact role. Picture how a virus gets into our cells. It has to attach and get absorbed before it can effect any changes. This particular virus, called HERV-W did just that. It contained a protein that allowed the outer wall of the cell to fuse with it. Syncytin is the name of the protein.

‘Syn’ is a common prefix in various words — synchrony, synesthesia, synonymous. It can be roughly translated to mean ‘same’, or same identity. Syncytin is a merger of two words — syn and cytin. The former means ‘same’ and the latter means ‘cell’. It’s how the virus first got into our cells — by merging.

It’s an important process because you want the growing embryo inside the mother to merge with the mother. It then creates a barrier interphase for maternal nutrition. It can feed the baby satisfied that it’s protected for as long as it grows inside it.

But there’s a problem.

If a virus can help facilitate the successful formation of a placenta, doesn’t it mean any other similar virus can infect it and subsequently the child?

True.

To prevent this likely occurrence, another viral protein is produced called suppressyn. It suppresses the entry of other retroviruses. Mini-scientists and engineer friends protect the child.

You’d be naively wrong to think the placenta’s primary role was nutrition. The first role is protection. The placental barrier is necessary to sequester the child in an environment free from the immune cells of the mother.

Recall that you were born from a fusion of the sperm and the egg. The sperm is from your father, and the egg is from your mother. By this definition, you were a foreign entity to the mother. A misfit protected from the immune cells of the mother. We owe a large part of this freedom to the placenta. According to a team of researchers, we also owe a large part of it to another group of viruses — HERV-K.

This group of retroviruses is known to suppress immunity to help the foetus grow with minimal harm. Protection from the very entity responsible for feeding you for nine months. When Andre-3000 asks:

I do wish I had scientist or engineer friends

He doesn’t know he had them from the start. One group creates a barrier interphase for successful feeding and formation of the placenta. Another prevents the invasion of other potentially harmful viruses. Then the other suppresses the immunity. The same mechanisms allow our strange group of lizards, the Mabuya, to give birth.

As far as egg-laying mammals go, few studies have been done to evaluate the presence of this viral gene. So far, none has been identified. As for the pouched mammals like kangaroos and koala bears, a small equivalent of the gene has been found. Since these marsupials have a shorter period when the embryo is dependent on the mother, they have a short-lived placenta. The virus has a say in this.

I will live forever

Placentae are known for various properties, with a central one being the ability to form any cell.

Any cell!

Inside our bone marrows lie cells with similar properties, but with a tiny caveat — one that makes the most important difference. The ones in our bone marrow can form any cell but not the placental cells. However, the placental cells can form any cell, including the multipotent variety of cells within our bone marrow.

Placentas have evolved in all vertebrates except birds. It implies the fusion of these retroviruses with other classes of organisms. That each of these inventions requires the adoption of these mini-scientists and engineers means they have the potential to live forever.

One group of viruses can do exactly that — HERV-H. These retroviruses have been identified in the stem cells of experimental stem cells. When their activity is suppressed, stem cells lose their potency.

Stem cells are the pools from whence we regenerate our other cells in the body. They are the spring from which our lives depend, replacing the old and dead cells while preserving functionality.

Consider your digestive system. The intestinal lining requires consistent replacement. Some cells can be sloughed off during digestion, and they need to be replaced. What’s more, these cells are not just protected by the mucous lining; the same mucous layer harbors viruses, the kind of viruses that feed on bacteria, known as bacteriophages.

Disrupting the replacement of the lining of the intestinal cells can cause untold pain. Disease may follow by creating easily accessible portals for invasion of the pathogenic bacteria. The replacement of the old or dead cells is necessary. It comes from a pool of stem cells. These cells have been noted to survive in their self-renewal property because of the HERV-H retrovirus.

If you listen keenly, you can hear them sing:

I’ma live, I’ma live forever

Potentially, provided the nutritional supply remains in good supply.

You see, viruses are not all bad. The media largely documents the criminal archetypes. The good ones are forgotten. In reality, the pathogenic, criminal ones are the misfits.

These pathogenic viruses give a bad impression of their capabilities while simultaneously playing a role in yet another process in evolution known as aggressive symbiosis, but that’s a topic for another day.

Having our lives shaped so much by viruses, it seems we are the misfits in this world. The large organisms living in a microbial world.

Taken out of context, misfits do tend to be misinterpreted.

What I’m trying to say is…

The Mabuya lizards don’t live the regular life of reptiles. It resonates with the lines by Killer Mike, the rapper:

I do not move like a regular Joe I do not wish for no regular life

It also applies to humans, whose unveiling happened after the human genome project revealed that about a tenth of our genome is from viruses.

In any society, scientists are a small group responsible for generating useful tools for the rest of the population. At a microbial level, it’s no different. We are alive because of our mini-scientists and engineers — the retroviruses.

They have allowed us, the misfits in this microbial world to survive.

[embed]This song inspired some of the lines used in this article. Source — YouTube