[Reading Science] Is Corona a Virus and Cholera a Bacterium?

Novel coronavirus. [Photo by YouTube screen capture]

[Asia Economy Reporter Kim Jong-hwa] The momentum of the novel coronavirus infection (COVID-19) is not subsiding easily. As a result, various types of sprays with antibacterial functions are selling well in the market. Products labeled with the promotional phrase "Antibacterial 99.9%" are reportedly gaining popularity.

One point to note here is the word "antibacterial." The meaning of antibacterial is to resist or eliminate bacteria. Ordinary consumers usually interpret the phrase "Antibacterial 99.9%" as meaning "eliminates 99.9% of bacteria." However, COVID-19 is a virus. So, are antibacterial products effective against viruses as well? To get straight to the point, they are effective. However, it is important to understand that bacteria and viruses are different entities.

The biggest criterion distinguishing bacteria from viruses is whether they are living organisms or not. Bacteria generally belong to living organisms. Living organisms have several characteristics: they can reproduce on their own, consume nutrients, digest, produce energy, respond to external environments, and evolve.

Bacteria meet these conditions, so they are living organisms. However, viruses cannot reproduce on their own. They must use the nutrients of other living organisms to reproduce. At the same time, viruses consume nutrients, digest, produce energy, respond to the environment, and evolve. Therefore, viruses are classified as entities in an intermediate state between living and non-living.

In other words, bacteria have both DNA and RNA as genetic material and can reproduce independently. In contrast, viruses have either DNA or RNA, but not both, and cannot reproduce by themselves. Viruses use the cells of other living organisms, called host cells, to reproduce.

When a virus enters a host cell, the protein shell that encloses its DNA or RNA is broken down, allowing it to use DNA or RNA that it does not have. At this time, the virus replicates itself to create new viruses. So, how are "variant viruses" created?

Variant viruses are created when problems occur during the virus's replication process inside the host cell. When the virus enters the host cell and causes the host cell to produce its genetic material, the host cell makes a mistake and produces a virus slightly different from the original virus. This results in a variant virus.

The current COVID-19 virus is a variant of the ordinary coronavirus that causes the common cold. Inside its corona-shaped shell covered with sharp spikes, there is RNA composed of 30,473 bases. Its base sequence is 79.5% similar to the SARS virus and 96% identical to the coronavirus that parasitizes bats. It is known that the coronavirus parasitizing bats recombined with other viruses to become a new variant.

A scene from the movie "Contagion," which warned of a pandemic caused by an infectious disease.
[Photo by YouTube screenshot]

Viruses are about 10 to 100 times smaller than bacteria. The typical size of bacteria is about 0.000001 meters, which is about one-hundredth the thickness of a human hair. Viruses are even smaller than this. Some types are said to be 1,000 times smaller than bacteria. They are not easily visible with ordinary microscopes and can only be seen with electron microscopes.

One of the famous infectious diseases we know is the Black Death (plague). It was a terrifying disease that killed one-third of the European population in the 14th century. This disease was caused by bacteria, specifically the plague bacterium, not a virus. Tuberculosis (caused by tuberculosis bacteria) and cholera (caused by cholera bacteria) are also bacterial infectious diseases. On the other hand, smallpox is an infectious disease caused by the smallpox virus. Severe Acute Respiratory Syndrome (SARS) in 2003, the novel influenza in 2009, and Middle East Respiratory Syndrome (MERS) in 2012 are all infectious diseases caused by viruses.

If viruses did not mutate, disease treatment would not be problematic, but the challenge is to create new vaccines that can resist each variant virus. However, infectious diseases caused by viruses tend to have high infectivity with low fatality rates, or high fatality rates with low infectivity. For a virus to spread widely, the host must survive for a long time and come into contact with many people. If the virus is highly toxic, the host dies quickly, preventing the virus from spreading further.

Bacteria are treated by antibiotics that destroy the bacterial cell wall to kill them or inhibit reproduction by preventing the synthesis of genetic material or proteins. Viruses are not composed of cells like bacteria, so they cannot be treated with antibiotics. Treatment involves using antiviral drugs to inhibit replication or, if antiviral drugs are unavailable, boosting immunity through rest to allow the body to overcome the virus on its own. This is why there are many deaths among the elderly and children when infected with viral diseases.