- Many a times when we hear the word virus, we think of pathogens. We label them that and move on. Actually the term virus itself comes from a Latin word which translates to poison. We seldom stop to think of viruses in a different light, and rightly so since they cause a great deal of suffering and death to human kind. I myself have faced the ungodly wrath of viruses more than a few times. But is there a silver lining to this menace?
1. VIRUSES 101
Considered the most abundant type of biological entity, viruses are found in every ecosystem on the planet. In fact, it is estimated that there are 100 million times more viruses on earth than there are stars in the universe. Yes, there are 10^31(that is ten with thirty one zeros for clarity) viruses on the earth alone. Who’s to speak for Mars and the rest?
Though millions of viruses are known to exist, only about 5000 types have been fully described in detail. Not only do they infect humans, but also plant, animals, and bacteria.
Viruses have the ability to replicate only when they are inside the cell of a host organism. This is so because they depend on the host cell to make the chemicals needed for them to replicate. It is only due to this ability to replicate that they are considered a type of life form.
Viruses are tiny, with most of them ranging from ten to three hundred nanometres in length. They vary from simple helical shapes to structures that are even more complex.
A complete virus is made up of nucleic acid enclosed with an external protective barrier known as a capsid. During an infection cycle, the virus attaches to the outer part of the host cell and penetrates the cell. Once inside, it degrades its external capsid and begins to replicate. After replication and maturation, the virus escapes causing death of the host cell. Other times however, the virus can remain dormant in the host cell until a later time. This is termed latency.
Viruses often get access into the human body through ;
- skin contact
- Body fluids
Transmission can be vertical, that is, from mother to child, or horizontal, from person to person. Prevention is always a challenge due to their extremely small size and their ability to survive for long outside a host. In humans, viruses cause diseases such as flu, chicken pox, influenza and the infamous HIV.
2. FOCUS ON THE DONUT, NOT THE HOLE IN IT
It is said that while pessimists see misfortune in every opportunity, optimists see opportunity in every misfortune. There is no argument that viruses indeed have the ability to cause serious harm, but there are always two sides to every coin. And it is this kind of thinking that has led microbiologists to discover numerous benefits of viruses, a few of which I have discussed below.
”When you are immunized, what happens is you have forces in your body pre-trained to recognize and defeat specific foes.”Seth Berkley.
Vaccines are preparations that provide immunity against a particular disease. Vaccines contain weakened or killed forms of the disease causing pathogen. Once these are introduced into the body, the body’s immune system recognizes and destroys the threat. The immune system will then keep a record of the microbe, making it easier to fight it off in subsequent exposure to the same pathogen.
Viral diseases are a nuisance. We however need the same viruses to try and prevent them. Weakened viruses are given as vaccinations to prevent viral infections. Examples of such vaccines include human papilloma virus vaccine, influenza vaccine rabies vaccine and chicken pox vaccine.
”If we value the pursuit of knowledge, we must be free to follow wherever that search may lead us.”Adlai Stevenson.
Viruses have proven to be a source of valuable information, previously unknown to man. They can be used to study the body’s immune response against them. This is so since they initiate immune responses in their hosts. Immune cells in the body known as T cells are vital in fighting off viral infections. They kill virus infected cells and also activate interferon, which stops the replication of viruses. They then keep a memory of the insulting virus so as to fight it off next time it dares to present itself. Mechanisms that the viruses use to escape the immune system are also studied. Viruses evade the immune system by mutating, that is, changing or masking some compounds on their surfaces so that they cannot be recognised by the immune cells.
Viruses can help scientists to follow brain pathways. We all know the brain is made up of about a hundred billion neurons with trillions of connections. Thanks to viruses however, a few of those pathways may be followed. Viruses that normally spread from neuron to neuron such as rabies and herpes are used. Scientists can therefore be able to map and better understand the neuron pathways. Of course, the harmful genetic material of the viruses is first modified. The virus is then introduced to the host, the neurons they infect identified, and their connections mapped. Through this, scientists have been able to trace the pathway for dopamine release, and this has caused great leaps in the management of Parkinson’s disease.
Also, since viruses are small organisms, they have a simple genetic makeup therefore providing simple models for study of genes. This is useful in assisting scientists to understand the biochemistry of higher organisms. Viruses shed light on functions of cells and processes such as DNA replication, transcription and translation. They also help us understand the process of reverse transcription, whereby a retrovirus is able to create DNA from an RNA template. The HIV virus is an important example of a retrovirus that undergoes reverse transcription, and this knowledge has been manipulated to make antiretroviral drugs which are key players in HIV management.
‘Everybody should have access to medical care- Paul Farmer.
Viruses play a vital role in the management of various illnesses. Bacteriophages are a type of viruses that infect bacteria. Phage therapy, a new therapeutic approach, uses bacteriophages to treat bacterial infections. The viruses infect the bacteria, causing their death, thus resulting in the clearance of the bacterial infection. Phage therapy has the advantage of specificity, since bacteriophages will only attack the bacterial cells, causing no harm to the human calls. It also does not stress the liver or produce major side effects, as opposed to conventional medicine. Bacteriophages are currently being used in places such as Georgia to treat bacterial infections that do not respond to conventional antibiotics, and they have been reported to be successful.
Viruses can also be used by molecular biologists to transfer useful genetic materials into host cells. The viruses are modified to make them safer by deleting part of their genome that is critical for replication. They are also be modified to target specific cells. This method has been used in gene therapy, where defective genes responsible for a disease such as cystic fibrosis are replaced using viruses as vectors or vehicles to deliver the correct genes to the cell.
Viruses also play a key role in the management of cancer. Specific viruses known as oncolytic viruses have the ability to infect and kill cancer cells. A number of viruses have been clinically tested in laboratories as oncolytic agents, though only a limited number of human trials have been performed. For example, the Seneca valley virus has been shown to have about ten thousand times more cancer cell killing capability than drugs used in chemotherapy. An oncolytic therapeutic agent known as T-vec successfully completed stage three clinical trials and was approved in October 2015 for the treatment of skin cancer.
”The world’s finest wilderness lies beneath the waves.” Wyland.
There are a very large number of viruses found in the oceans of the earth, particularly the bacteriophages. They can occur in concentrations of up to nine hundred million viruses in one millilitre of water. The bacteriophages kill bacteria found in the ocean which are often present in large numbers since most of untreated sewage is always discharged into oceans. Thus in doing so, the concentration of bacteria in the oceans is reduced.
Despite these and numerous other benefits, man still fights hard to eradicate viruses from the surface of the planet. However in this battle for dominance, they keep fighting back. If there is one thing we can learn from viruses, it is the art of resilience. They adapt to change, and are always ready with a counterplan whenever scientists are close to a breakthrough.
We have come a long way in preventing viral diseases over the last century. A sure-fire cure however still evades us since viruses keep mutating and replicating at high rates. They have existed long before us and must have picked up a few tricks along the way.
Someday soon some brainy scientist in a lab somewhere will discover a way to put them down once and for all. However, in the meantime, it wouldn’t hurt to focus more on their good side. Sure, viruses may seem to cause more harm than good, but we can’t let that kind of negative thinking get to us.
The challenge of discovering beneficial viruses. Journal of medical microbiology, 58(4), 531-532
S.L Young. Viral gene therapy strategies: from basic science to clinical application. The journal of pathology, 208(2), 299-318
ARTICLE BY STEPHANIE.S.OJINA