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Viruses – An Analysis

Jax Norman

Environmental Science 20

Jennifer Johnsgaard

December 15, 2023

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No matter where an individual, animal, or plant goes, viruses follow them. Despite this,

the easiest way to detect one is by seeing the impact of one, and not the virus itself. Viruses are

well known and can strike fear and paranoia into a society. The world has recently seen the

impact a virus can have on the daily life of a community, even on the global scale. Although

viruses can cause all this panic, most are able to coexist peacefully with their host. The idea of

viruses is often misunderstood by people outside of the scientific community, which can cause

fear, misinformation, and confusion to spread very quickly.

The term “Virus” can often be muddled down and confused for other pathogens of similar

biological makeup. It can be quite stigmatized, despite the fact that practically every organism on

life is infected with viruses right now. The term is Latin, literal for ‘slimy liquid, poison’ (Virus

Definition & Meaning, 2023). Diseases have impacted every part of human and non-human

history. Even if the events of a pandemic or epidemic were not recorded, there are often

biological or religious records of such things. An abundance of pathogens in a sediment’s air

pockets which dates to a similar time of a seeming plague of unknown origin, could mean that

these people of the past simply suffered from an unknown virus. In Ancient Greece and the

Roman Empire, sudden sickness would be chalked up to poor miasma or a vital humour being

out of balance (Taylor et al., 2014).

Only until the sixteenth century, did researchers begin to make a tie between infectious

materials, and one’s health. Girolamo Fracastaro was one of the first to suggest this relation, as

well as Agostino Bassi. Bassi did work on studying the diseases of silkworms, and came to a

similar conclusion. The invention of the microscope by Antoni van Leeuwenhoek greatly

revolutionized the scientific world, causing a plethora of new discoveries to be found.

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Figure 1.1 – Leeuwenhoek’s Micrscope

The Hershey-Chase experiments were able to prove the existence of deoxyribonucleic

acid, more commonly known as DNA, within bacteriophages, a category of viruses. It also

proved the fact that genes were made of DNA. This was a series of experiments conducted by

Alfred Hershey and Martha Chase in Cold Spring Harbour, New York. The experiment that

garnered the most recognition from the scientific community was the Waring Blender

experiment: proving DNA was what genes were composed of. The scientific community was

wary and skeptical of Hershey and Chase’s arguments and experiments for decades beyond the

initial experiment. (Hernandez & Dhein, 2019)

Despite this, many diseases or viruses were not given names or identified until the early

and middle of the 1900s. The Bubonic Plague or Black Death was not identified at the time,

which is possibly why it was so deadly. The smallpox pandemic was indeed caused by a virus,

and it shows the deadly consequences a virus can have on the human population if not properly

prepared.

The origin of viruses is often debated, as evidence can be hard to come by. Many theories

have popped up, but also been disproven and eventually fizzled out of relevant conversation.

Two have remained. These theories are that viruses have come from degenerate cells, or vagrant

genes. Scientists believe that viruses have possibly been derived from cell degeneration: a

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condition that can cause a cell to alter its shape and purpose (Cell Degeneration and Necrosis,

n.d.). On the other hand, some may believe that some nucleic acid from DNA becomes

displaced, and instead of becoming degraded and unusable, take upon their own survival and

replicate. These theories are not recent, and first appeared in the twentieth century. Despite this,

not many advancements in the origins of viruses have been deducted. Advancements in computer

technology like being able to collect data from the rapid sequencing of cellular versus viral

genomes allows scientists to understand the relation between viruses just a little bit better.

Viruses can affect their hosts in a multitude of ways (Introduction to Modern Virology,

n.d.). Surprisingly, most viruses have very little or no impact on the health of their host, but some

will. This can vary from a virus entering and leaving an organism very quickly, causing them to

be ill for a few days or weeks, or the contrary, where the virus will lay dormant in an organism

for a long time, and then only when the virus leaves will the organism begin to suffer from an

illness.

For a microorganism to be classified as a virus, it has to be an incredibly small

(approximately 100 to 1000 times smaller than the cells in one's body, to the point where they

can be invisible even at high magnification) piece of genetic material like DNA or RNA (known

as a genome) within a “capsid”--a protective layer (Viruses: Definition, Types, Characteristics &

Facts, 2023). This capsid will often have another layer around it called an envelope. Viruses that

do not have this second layer are described as “naked viruses”.

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Figure 1.2 – Artist’s rendition of virus anatomy

Viruses are not composed of cells like bacteria, and thus do not have a cell's reproductive

abilities. Instead, a virus will have genetic guidelines, and use a planted host cell’s apparatus and

molecular components to reproduce. Thus, the livelihood of such an organism depends on

locating a host.

As mentioned above, viruses can be broken down into categories. These categories are

based on their similarities, physical and genetic. This can be determined based on subjects such

as their size, their methods of reproduction, their shape, or their genetic makeup. Some

well-known types would be influenza viruses, hepatitis viruses, and coronaviruses.

Viruses are transmitted to the body via your mucous membrane–also known as

mucosa–the tissue that lines an individual’s organs in many systems such as the digestive,

respiratory, and reproductive system (Mucosa: Function, Anatomy & Definition, 2022). The way

this is useful to viruses is that any fault or break in an individual's skin is a potential entryway for

said viruses.

The steps for a virus reproducing are relatively similar across most categories. Experts

classify the process into a step-by-step program that is seldom strayed from. This program is

described as the following: attachment, entry, replication, assembly, and release.

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Viruses, once having breached the skin of an individual, are able to get into living cells in

multiple ways. Using the cell’s receptors that are intended to receive proteins from the outside,

viruses can make their way inside a cell via disguising themself as such a protein. Meanwhile,

some viruses can attach or fuse directly to a host cell to get inside, and do not bother with any

disguise. The final way is specific to bacteriophages, who are able to inject their genetic makeup

into bacteria. This means only a portion of the virus is needed to enter the host cell.

Once the virus (or components of the virus) are freely inside the host cell, there are two

options of cycles for a virus to reproduce. Occasionally, a virus may use both cycles. These

cycles are known as the lytic cycle and the lysogenic cycle. The lytic cycle involves the virus

making use of the host cell’s already existing machinery to reproduce. Parts of the virus will

collect, the genetic material being composed within the capsid, and thus they are able to produce

copies of themselves. The copies will eventually overwhelm the host, causing them to burst, and

the cycle repeats. This is often seen in adenoviruses (Virus | Definition, Structure, & Facts,

2023), a category of viruses that can cause cold-like symptoms.

Figure 1.3 – Adenovirus under the microscope (seen in purple clusters).

On the other hand, some viruses will appear dormant for a relatively long while. This is

evident in the lysogenic cycle. The virus will enter the host cell, and then remain inactive within.

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This means that the host cell will reproduce without any alarm or knowledge that a virus is

present. Now each new copy of the host cell will contain the virus, and a particular trigger can

cause the cell to burst. These triggers can vary, but are mainly stress, temperature alterations, and

chemical factors. A common example of a virus that follows the lysogenic cycle is shingles, or

VSV.

Figure 1.4 – Shingles (Varicella Zoster Virus) under the microscope (seen in circular red clusters).

Viruses could be considered a keystone species within an environment, as they are

incredibly significant to the environment around them. They have the same role of a predator,

just on a microscopic level. It is highly debated and a hot topic within the science world if

viruses are considered biotic or abiotic: living or nonliving. Viruses depend on other lifeforms to

live, in contrast to bacteria or similar single-celled microorganisms. Parasites and viruses are so

similar many consider viruses to be a type of parasite due to this. Despite a virus containing

DNA or RNA, it is still highly controversial if it is valid to call a virus alive or not. It is said that

viruses can be considered on the precipice of life. They possess attributes of both objects, such as

the ability to form crystal lattices, and life, having the ability to reproduce.

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Figure 1.5 – Crystal lattice of an Orsay-virus particle.

Since viruses are much too small to be seen with an electron microscope, the way

scientists detect their presence is by more indirect ways, as mentioned in the introduction.

Usually, this is done in three ways: multiplication, serology, and the detection of nucleic acid.

Multiplication in an area suitable for a virus and sudden effects can signal there may

indeed be such a virus there. This means that for a virus to be somewhere, there must be living

cells for the virus to multiply from. Thus, anything deceased will not have viruses present.

Viruses will often be noticed just because a professional may suspect one is there to symptoms.

It’s particularly difficult to know if one is there if there is no physical evidence. Professionals

may take a culture (most often an organ culture) to see if it changes in any way. If it does, that

most often means a virus is present. A virus or group of viruses will change the cell it has used as

a host, this is known as pathology. This can be noticed and seen as a way to notice and record a

virus’ presence. Simply, this method is the cultivation of a virus within a suspected culture.

These tests are simple, but are slow to give results.

Serology is the study of fluids, primarily antibodies. Antibodies are specific proteins

within one’s body that are produced by the immune system, and their purpose is to combat

foreign materials, known as antigens (Antibody Serology Tests, n.d.). These antibodies are

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released into bodily fluids, most evidently the blood of an individual. This is where antibodies

are obtained, as the blood will clot and leave the antibody on its own (known as an antiserum).

These antibodies/antiserum can be injected into an individual, and if the antibody perceives the

virus, it will be able to bind to it. This means the virus’ purpose and infectivity will come to a

quick halt. Antibodies can also be used to find viruses in cells. When a cell is infected, the

antibody will not be able to enter the cell, thus notifying that this cell is indeed infected with a

virus. Unfortunately, this method tells the reporter nothing about the virus’ genome.

The last method is simply finding nucleic acid where it usually isn’t. This is done using

PCR (polymerase chain reactions), which are triggered by DNA. They are inserted in, to see if

these chain reactions will properly occur. If the virus’s genome is RNA, it will have to be

converted to DNA via a primer first, a short strip of nucleic acid that can be used to identify

genomes (,, 2023). Each virus will have their own PCR sequences, and if one of these sequences

is chosen to be tested on, and the result comes back positive, the exact virus can be identified.

Unfortunately, this testing system can be incredibly sensitive and easy to fail. It can also only

detect very small amounts of these DNA or RNA genomes. This has the advantage of detecting

viruses in their true form, though, allowing mutations to be avoided. This will bill a research

centre the same cost as a cultivation lab.

Viruses have persisted through every aspect of life on Earth, and possibly beyond that.

Some scientists theorize that the first “alien” humanity finds could simply be a virus. The history

of viruses is relatively new, even just the history of diseases in general. The medical revolution

was not as long ago as people may imagine. The fear and paranoia that viruses can bring along

can easily be subsided with the proper information and knowledge about the topic. From

knowing the history of virology, to understanding how they are detected, this all makes the world

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of viruses seem a little less murky. Truly, viruses are fascinating and incredibly important to the

Earth’s ecosystem, whether humanity enjoys it or not.

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Viruses – An Analysis