What Is Coronavirus and How Do Humans Defeat It?

Accompanying worldwide awareness of the COVID–19 pandemic is an understandable fear of the disease as well as misunderstandings of what causes it. Microscopic germs, invisible to the naked eye and which can spread silently from person to person, are the cause of this infectious disease.

As of April 2020, there is no proven treatment or ‘cure’ for coronavirus infections. The best prevention against contracting the virus is to wash one’s hands with soap after touching public surfaces, as well as to refrain from touching one’s eyes, nose and mouth — points of entry for the virus.

Image describes the steps of proper handwashing: wet hands with clean water; apply soap; lather hands by rubbing them together (palms, backs of hands, between fingers, and under nails); scrub hands for at least 20 seconds; rinse hands under clean, running water; and air-dry hands or use a clean towel. Image from CDC.

The steps of proper handwashing, from a CDC publication “Stop Germs! Wash your hands.” (English, Español)

Lately, President Trump has been enthusiastically urging people to self-medicate with a chemical called hydroxychloroquine, a drug prescribed for malaria patients as well as those afflicted with lupus. Despite no scientific evidence that hydroxychloroquine prevents COVID–19, Trump has been insisting that there are “some very strong signs” that the drug is an effective preventative measure.

Doctor Radha Rajasingham works as an assistant physician for the University of Minnesota’s Medical School, Infectious Diseases and International Medicine division (UMN). She and her team have been performing clinical trials on the effectiveness of hydroxychloroquine against contracting COVID–19.

The drug is thought to disrupt the method by which coronaviruses SARS-CoV and SARS-CoV-2 attach themselves to host cells inside of a person’s airways. Hydroxychloroquine is not a vaccine against COVID–19 nor a treatment for a person already infected with the new coronavirus.

Watch Dr. Rajasingham’s interview with MEGA:

The UMN’s ongoing clinical trials on humans regarding the efficacy of hydroxychloroquine will be completed in the first weeks of May.

Below we have detailed some of the science and history behind viral and bacterial infections, as well as other ongoing research regarding battling the new coronavirus.

Historical study of the invisible enemy

The term ‘epidemic’ was first used in a medical sense around the turn of the fourth century B.C. in reference to the appearance of a collection of illness symptoms that occurred in people in the same area at the same time.

In the 11th century A.D., Persian physician Ibn Sina wrote on epidemics, noting that tuberculosis could be transmitted from person to person via breath or through contaminated water or dirt. His medical encyclopedia, The Canon of Medicine (Al-Qanun fi’t-Tibb), was used as the standard medical textbook by Islamic and European medical practitioners for almost 700 years.

Germs — tiny disease-causing organisms or ‘microbes’ invisible to the naked eye — had been suspected for well over a thousand years by various cultures. However, direct evidence wasn’t possible until the invention of the optical microscope in 1676, when bacteria (single-celled organisms) were observed for the first time by Dutch microscopist Antonie van Leeuwenhoek.

Drawing of the first bacteria ever seen by humans under an optical microscope.

Figures A–F: The first bacteria seen by humans, observed & drawn by Antonie van Leeuwenhoek. Image courtesy Huy Dang (CC 4.0)

It took another 200 years before European scientists accepted the notion that microbes cause disease, known as ‘germ theory.’

Belief in the unseen

Before germs were well-known as agents of illness, it was believed that foul odors or ‘bad air’ emitted from decaying organic matter caused disease; this was ‘miasma theory.’

In the 1840s, physician Ignaz Semmelweis demonstrated that patient mortality rates were drastically reduced by the simple act of a medical practitioner sanitizing their hands before touching a new patient. He had doctors first wash their hands with soap then with a bleach solution, which removed not only unpleasant odors but also the bacteria that lingered unseen.

The three decades following the late 1850s saw a shift in European medical opinion away from miasma theory due to the revelations of several scientists.

Notable among those scientific contributions are those of Robert Koch, who demonstrated that a given disease is caused by a specific organism, and Louis Pasteur, who developed some of the world’s first vaccines. A ‘vaccine’ is a sample of weakened microbes that, when introduced inside a host’s body, cause an immune system response that protects the body against future full-strength microbes of the same type.

Illustration of a vaccine being introduced into a person's body through injection into the upper arm. Text: vaccines may contain weakened or dead microbes.

A vaccine introduced via injection. Image courtesy Bruce Blaus (CC 4.0)

By the 1890s, the miasma theory of contagion had been supplanted by germ theory. Around this time, viruses, infectious particles much smaller than bacteria, were also discovered.



Pathogens infecting pathogens

Both bacteria and viruses can be ‘pathogens,’ biological substances that cause disease in plants and animals. Unlike a bacterium, a ‘virion’ (an individual virus particle) cannot reproduce outside of a living host.

Virions are the most abundant biological entities on Earth and can infect bacteria and fungi in addition to plants and animals. They consist of genetic material as well as polymerase enzyme — complex structures that help copy the genome — all wrapped in protein coating(s).

Illustration of a basic virus. The outer part of the virus is called the "envelope" which surface is covered with protein. Below the envelope is the "capsid" another layer of protein coating that protects the genetic material inside as well as the enzymes needed to copy the viral genome.

The basic structure of a virion, or virus particle.

Virus particles reproduce by attaching themselves to a living cell, penetrating the cell wall, and releasing genetic material inside the host cell. The virus then uses the host cell to manufacture and assemble copies of itself, virions which burst forth or are otherwise released from the host cell.

Most viruses are about a hundred times smaller than bacteria and cannot be seen through an optical microscope. It was not until the invention of the electron scanning microscope in the 1930s that the first high-resolution images of viruses became available.

Combating the invisible

Antibiotics, drugs that kill bacteria cells but leave the body’s own cells unharmed, had been in use for thousands of years in ancient Serbia, China, Egypt, and Greece — moldy bread applied to wounds could prevent or mitigate topical infections.

Penicillin is a purified antibiotic substance derived from specific molds. Discovered in 1928, it was first refined and then mass-produced over the next 15 years. The drug was the first effective treatment for bacterial infections such as pneumonia, and was extraordinarily helpful in combating infection suffered by wounded Allied soldiers during World War 2.

Antibiotics are not harmful to viruses; specific antiviral drugs must be used to combat these pathogens, which are highly susceptible to mutation. Antibiotics will successfully treat bacterial infections present in a patient alongside a viral infection, such as bacterial pneumonia.

To combat the new coronavirus in the year 2020, an experimental antiviral drug remdesivir is being tested presently in China, France, and the United States. The drug targets the polymerase inside a virion; without this enzyme, the virus is unable to replicate itself.

Because all viruses carry and require one or another version of these enzymes, the hope is that remdesivir, initially developed (not very successfully) for treating Ebola virus infection, may prove effective against the novel coronavirus strain propelling the present pandemic.” — Bruce Goldman, science writer for Stanford University School of Medicine

A vaccine is in the works that will target the protein spikes on the outside of the coronavirus. Coronaviruses typically attach themselves to cells in the upper respiratory tract, but a mutation in SARS-CoV-2 allows its virions to attach themselves via their spikes to an enzyme lining the cells of our lower respiratory tract — part of what makes this pandemic dangerous.

Illustration of a coronavirus particle and the ACE2 enzyme lining the cells of human respiratory tracts, to which the virion attaches itself.

SARS-CoV-2 virions attach themselves to the ACE2 enzyme lining the cells of humans’ respiratory tracts (credit below)

Conclusion

Though there is yet no cure for COVID–19, neither is there a cure for the common cold, an infection of the upper respiratory tract predominantly caused by coronavirus and rhinovirus variants.

Physically distancing oneself from others (who may be infected with the virus and not know it) has been shown to be effective at limiting the transmission of the virus. The best prevention against contracting the virus is refraining from introducing virus particles into one’s body, which is accomplished through touching a contaminated surface and then touching one’s face.

ACE2 enzyme image courtesy of Eric/EMW (CC 3.0), SARS-CoV-2 image (and cover image) courtesy of Scientific Animations (CC 4.0).

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