6 New Findings About Viruses

viral spread

The virus was discovered in 1892, yet even in 2018, researchers are still uncovering new secrets about these infectious invaders. Viruses aren’t exactly living things and have no way to reproduce themselves. Instead, they’re made of genetic material, usually DNA or its chemical cousin RNA, wrapped in a protein coating. Because of their ability to integrate their genetic code into their host’s code, viral genes have been found to be hidden in the genes of many organisms, including humans. But exactly how and why viruses play their genetic tricks remains a mystery that researchers in a wide range of fields, from evolutionary and molecular biology to neurology and chronic disease research, are trying to solve.

Here are six new things scientists have recently learned about viruses.

An ancient virus in the human brain

The preservation of genetic remnants of an ancient virus infection in the neurons of animal brains, including human brains, may hold the key to how the thought process works, researchers report in two papers published in January in the journal Cell. The researchers found that a gene called Arc, which is present in tetrapods, is the genetic code left over from an ancient virus. In addition, they found that this gene is critical to the ability of nerve cells to build certain types of small packages of genetic material and send them to other nerve cells. This process explains how nerve cells exchange the information they need to reorganize their cells.

Researchers say that brain functions including conscious thought and the concept of “self” may only be possible with this process. And if the process doesn’t work properly, synapses or connections between neurons may be dysfunctional. More research is needed, they say, to understand how the Arc gene becomes part of an animal’s genome and exactly what information is passed from one neuron to another as a result of Arc’s instructions.

Viruses really do fall from the sky.

A long-standing mystery about viruses was finally answered in 2018. The reason why genetically similar viruses can be found far apart on Earth is that viruses can travel through the atmosphere via air currents. In a paper published in January in the Multidisciplinary Journal of Microbial Ecology, the researchers report that viruses can hitch a ride on soil or water particles and swing high into a layer of the atmosphere known as the free troposphere, then end up lying down in a whole new place.

The researchers also found that when viruses reach the free troposphere, which is about 8,200 to 9,800 feet above the Earth’s surface, they can travel farther than they could at lower altitudes. It turns out that the free troposphere is teeming with viruses, and because of its internal air currents, a square meter of the Earth’s surface could be showered with hundreds of millions of viruses in a single day, the researchers said.

Alzheimer’s disease and viruses

The theory that viruses may play a role in Alzheimer’s disease has gained more support from a study published in June in the journal Neuron. Researchers looked at nearly 1,000 post-mortem brains from multiple brain banks, including those of people with and without Alzheimer’s disease. They screened gene sequences extracted from these brain tissues and determined which sequences were human and which were not. They found that the brains of people who died of Alzheimer’s disease had up to twice as much of two common strains of the herpes virus compared to the brains of people who did not have Alzheimer’s disease.

The researchers note that it’s not entirely clear what role the virus may play in the development of Alzheimer’s disease. The viruses may be part of the cause of the disease, or they may simply accelerate its progression. But it’s also possible that they don’t play a role in the disease at all and find some other cause in Alzheimer’s patients, the researchers said.

Giant viruses invent their own genes

Giant viruses are more than twice the size of regular viruses and their genomes are complex.In June, researchers reported that so-called orphan genes, which are found only in the giant virus known as Pandora, actually originate from the virus itself. In fact, the researchers found that while random mutations are common in nature, these viruses are exceptionally rich in creating new genes. In addition, the orphan genes created by the Pandora virus vary from virus to virus, meaning that they are unlikely to have originated from a viral ancestor, according to the researchers. Exactly why the Pandora virus seems to produce new genes and proteins on a regular basis is unclear, but this discovery could change the way researchers study this family of viruses. Future research should focus on finding the mechanisms that drive the process by which the Pandora virus invents new genes and identifying the evolutionary forces that drive these viruses.

Viral genes may play a role in addiction

An age-old viral infection may play a role in today’s human addiction. Genetic traces of a virus called HK2 are more common in people with drug addiction than in those without, researchers reported in September in the journal Proceedings of the National Academy of Sciences. Remnants of the HK2 virus are found in only 5 to 10 percent of people, the researchers said, suggesting that a relatively recent viral infection, perhaps one that occurred 250,000 years ago, serves as the culprit. In today’s humans, genetic information left over from the virus may play a role in the release of the neurotransmitter dopamine, which is important in how the brain responds to pleasure, the researchers said. More research is needed to determine exactly how HK2 traces affect people’s addictive behavior, they said.

Wake up, herpes virus!

Herpes simplex virus infections are common, with more than 80 percent of the world’s population infected with the herpes simplex virus (HSV). The virus often remains in dormant mode in the body, which is beneficial to the infected person because the virus does not cause symptoms during the dormant period. However, the immune system also has a harder time detecting and eliminating the virus while in a dormant state.

In October 2017, the researchers reported in the journal PLOS Pathogens that they had figured out how to induce the virus into a dormant mode and also found key proteins involved in waking the virus up. The findings could have implications for the treatment or prevention of herpes infections, the researchers said. The researchers say the results could point to ways to target certain viral proteins to prevent the virus from waking up, thus preventing symptoms and transmission of the virus to others, or could lead to ways to keep the virus “awake” so that the immune system can eliminate it.