Brief Summary

Are viruses living or non-living? Not only is this a debate among scientists but viruses can also be created in a lab. Viruses consist of a piece of genetic information (DNA or RNA) that is surrounded by proteins. They insert this genetic information when they infect the host cell (human or bacteria). It is less known that the human body has many different viruses that are essential to the functioning of our bodies, which is referred to as the human virome. Human DNA consists of virus DNA remnant that was once believed to be junk DNA because its function was unknown. Ancient Retrovirus (RNA) has been found in human sperm and eggs. The life cycle of viruses consists of a four-step process. To learn more read sections 1 through 3.

 

 

Section 1

What are viruses?

Viruses are believed by some to be living and non-living by others due to individual differences of the definition of life. They are submicroscopic (smaller than microscopic) inanimate complex organic matter that require a living host to grow and reproduce inside. Those who believe they are non-living believe so because they have no metabolism and cannot replicate or evolve without a host. Living hosts can include humans, animals, plants, fungi, and even bacteria. They are not considered living organisms by some because they must infect a host cell to sustain life even though some can survive on surfaces for long periods of time (Fooks, 2020). “When found outside of these living cells, viruses are dormant” (Merriam-Webster, n.d.). Viruses are so small that they cannot be viewed under an optical microscope (which uses visual light to magnifies images. An electron microscope (EM) must be used to view viruses. An EM uses a beam of accelerated electrons to illuminate and magnify submicroscopic particles with electromagnetic lenses while in a vacuum. To further describe how small viruses are Fooks (2020) explains that viruses are 10 to 100 times smaller than the smallest bacteria. This size difference allows viruses to infect bacteria. Viruses that infect and replicate in bacteria are called bacteriophages or just phages.

 

(0814 Structure of a bacteriophage medical images for PowerPoint, SlideTeam, n.d.)
 

Viruses consist of either DNA or RNA genetic material that is “surrounded by a protein shell called a capsid” (Fooks, 2020). According to Fooks (2020) their shell can sometimes be surrounded by protein or fat molecules. Some viruses have an extra membrane that that covers this shell while some do not. When a virus has this extra membrane that surrounds the shell it is called an envelope and when a virus doesn’t have an envelope it is called a naked virus. These surface proteins “may project glycoprotein protrusions” (called peplomers) and these protrusions come in many forms, which can be shaped like a mushroom, triangular, or spikes (Fooks, 2020). Also, a virus’ “protrusions bind only to certain receptors on a host cell and determine what type of hosts or host cell a virus will infect and how infectious that virus will be” (Fooks, 2020).

 

(Virus-2 Image, Govind, 2013)
 

How viruses survive and reproduce

Did you know that not all viruses cause disease? It is often unknown that the human body hosts a vast number of different viruses that are essential to the functioning of our bodies. This large number of viruses that are a part of us are referred to as the human virome. As a matter of fact, “Eight percent of our DNA consists of remnants of ancient viruses, and another 40 percent is made up of repetitive strings of genetic letters that is also thought to have a viral origin” (Arnold, 2020). Retroviruses (have RNA as its genetic material) can insert their genes into human chromosomes and have been found in eggs and sperm.

As illustrated in the Life Cycle of Viruses’ image below:

  1. Viruses attach to host cells through connecting specific proteins on the cells surface to its protein protrusions and injects its RNA or DNA into the cell.

  2. The virus infects the hosts cell by inserting its genetic material.

  3. The genetic material then starts the reproducing process and hijacks the cells ribosomes (Fooks, 2020). During the hijack process the proteins that a host’s cells use to sustain its life are used by the virus instead synthesizing viral proteins. “The virus takes advantage of components within the host cell, such as ATP (adenosine triphosphate) for energy, and amino acids and fats to make new capsids and assemble new viruses” (Fooks, 2020).

  4. After the virus reproduces (make several copies of itself) within the host cells they eventually burst out (the process called lysis) and kills the host cell. When viruses do this, it’s called viral replication and is what causes illness.

After the new viruses burst out of a cell, they go on to infect other host cells, and even new hosts. Many virus infections last seven to ten days but some may linger for weeks depending on the severity of the infection. Furthermore, some viruses can also infect your cells and remain dormant for many years.

 

(Shutterstock_627695183, Goodman, 2016)


 

Bacteriophages infect cells slightly differently but reproduce the same as other viruses. It is different in that the DNA is injected into the bacteria cell through the phage as the (Structure T4 bacteriophage mode model attachment injection) image shows below. Just like with other viruses’ after impregnation phages replicate in the bacteria by producing many copies of itself and then destroys the host cell.

 

(Structure T4 bacteriophage mode model attachment injection, Encyclopedia Britannica, 1994)


 

Section 2

How viruses affect us

Viruses cause diseases and usually specifically affect a specific part of the body they attack, for example the respiratory tract, liver, or blood. Some common viruses include:

  • SARs-COV-2 (COVID-19)

  • HIV (human immunodeficiency virus)

  • varicella-zoster (chickenpox)

  • herpes zoster (shingles)

  • influenza (flu)

  • rabies

  • pneumonia

  • sinusitis (sinus infection)

  • hepatitis

  • common cold

Similarly, to when our bodies ride itself of a bacterial infection our bodies do the same to rid itself of a viral infection. Symptoms may include coughing, stomach cramping, diarrhea, nausea/vomiting, sneezing, and tiredness.
 

What do we do to treat viruses?

Currently vaccinations are used in an attempt to prevent many of the viral infections that viruses cause. “Antivirals have been engineered that can treat some viral infections, such as Hepatitis C or HIV” (Fooks, 2020). Many doctors recommend letting a viral infection run its course because there is a lack of treatments for most viral infections.

 

Section 3

What we do with viruses

Bacterial infections can be treated using phages. This is referred to as phage therapy. It “was developed back in the 1920s and 1930s in Eastern Europe and the Soviet Union (Tankeshwar, 2021).” Drug resistant bacteria has made phage therapy recently re-emerge. For example, “In 2019, the FDA approved the first US clinical trial of intravenously administered bacteriophage therapy (Tankeshwar, 2021).” We also use viruses to create vaccines. Furthermore, viruses are not only used in gene therapy but also cloning. Moreover, did you know that viruses can be assembled in a lab from scratch? According to Gelbart (2015) the recipe involves mixing purified protein and purified nucleic genome in water under the right conditions (salt, acidity, and temperature) then in time infectious virus particles will spontaneously develop.
 

Positive and negative outcomes of what we do with viruses

The obvious negative outcome would be disease and the effects it has on our health. Another negative outcome is that some viruses cause cancer. Cell and molecular biology find viruses extremely important as they introduce genes into cells that are being studied and contribute to the studies of genetics, molecular genetics, DNA, DNA replication, RNA processing, transcription, immunology, and translation protein transport. Viruses are also used for gene therapy in the efforts to fight cancerous cells by introducing mutated genes into the cells. Most importantly, something that needs regulated when it comes to vaccines is that labs are cooking up all kinds of viruses that could infect us. Lab leaks occur which could potentially be devastating. In fact, lab leaks are quite common as there was at least at one lab leak a year from 2001 to 2021.
 

Reference

Arnold, C. (2020 January 9). The non-human living inside of you. https://www.cshl.edu/the-non-human-living-inside-of-you/

Encyclopedia Britannica. (1994). Structure T4 bacteriophage mode model attachment injection. [Image]. https://cdn.britannica.com/43/4943-004-5350FC7A/structure-T4-bacteriophage-mode-model-attachment-injection.jpg

Fooks, C. (2020 April 13). What’s the difference between bacteria and viruses?. https://www.drugs.com/medical-answers/difference-between-bacteria-virus-3503840/

Gelbart, B. (2015 January 29). Five intriguing facts about viruses. https://www.chemistry.ucla.edu/news/five-intriguing-facts-about-viruses

Goodman, A. (2016 December 19). Shutterstock_627695183. [Image]. https://www.thegreatcoursesdaily.com/wp-content/uploads/2020/02/shutterstock_627695183.jpg

Govind, P. (2013 November 15). Virus-2. [Image]. https://medblog.medlink-uk.net/pallavig/files/2013/11/virus-2.jpg

Merriam-Webster. (n.d.). ‘Virus’ vs. ‘bacteria’. https://www.merriam-webster.com/words-at-play/virus-vs-bacteria-difference

SlideTeam. (n.d.). 0814 Structure of a bacteriophage medical images for PowerPoint. [Image]. https://www.slideteam.net/media/catalog/product/cache/960x720/0/8/0814_structure_of_a_bacteriophage_medical_images_for_powerpoint_Slide01.jpg

Tankeshwar, A. (2021 May 30). Bacteriophage: structure, replication, uses. https://microbeonline.com/bacteriophage-structure-replication-use/