Understanding SARS-CoV-2


By Henrylito D. Tacio


The best way to fight your enemy, someone said, is to get acquainted with your opponent well.  In the case of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), you need to know how it attacks so you get to be prepared for it.

Viruses are so unlike bacteria, which are microscopic, single-celled organisms that thrive in diverse environments.  A virus is a small parasite that cannot reproduce itself.  However, once it infects a susceptible cell, a virus can direct the cell machinery to produce more viruses.

“Most viruses have either RNA or DNA as their genetic material,” states the fourth edition of Molecular Cell Biology.  “The nucleic acid may be single- or double-stranded.  The entire infectious virus particle, consists of the nucleic acid and an outer shell of protein.  The simplest viruses contain only enough RNA or DNA to encode four proteins.  The most complex can encode 100 to 200 proteins.”

RNA, abbreviation for ribonucleic acid, is a complex compound of high molecular weight that functions in cellular protein synthesis and replace DNA as a carrier of genetic codes in some viruses.  DNA (deoxyribonucleic acid), on the other hand, is a self-replicating material which is present in nearly all living organisms as the main constituent of chromosomes.

Viruses are found in almost every ecosystem on this planet and are the most numerous type of biological entity.  “Since Dmitri Ivanovsky’s article describing a non-bacterial pathogen infecting tobacco plants, and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1989, about 5,000 virus species have been described in detail, of the millions of types of viruses in the environment,” Wikipedia reports.

The word “virus” is derived from the Latin neuter virus which refers to poison and other noxious liquids.  A meaning of “agent that causes infectious disease” is first recorded in 1728, long before the discovery of viruses by Ivanovsky in 1892.

In an article which appeared in Biology Direct (20016), it was stated that viruses can infect all types of life forms – from animals and plants to microorganisms, including bacteria and archaea (that which constitute a domain of single-celled organisms).

The virus that is causing panic around the world is called coronavirus.  Corona means “crown,” and coronaviruses have a “crown” of protruding points on their surface that give them a characteristic appearance when seen under a microscope.

“There are many different kinds of coronaviruses,” says Dr. Lisa Maragakis, senior director of infection prevention at the Johns Hopkins University.  “Some only affect animals.  Some have been circulating among human beings for years, causing mild colds.  Others have caused small, severe human disease outbreaks in the past, such as the coronaviruses that caused SARS in 2003 and MERS in 2012.  The new coronavirus is different from thee, and was only identified in December 2019.”

The World Health Organization (WHO) reports that SARS CoV – which stands for Severe Acute Respiratory Syndrome coronavirus – first infected humans in the Guangdong province of Southern China in 2002.  An epidemic of SARS affected 26 countries and resulted in more than 8,000 cases in 2003.

MERS CoV – Middle East Respiratory Syndrome coronavirus – was first identified in Saudi Arabia (where 80% of human cases were reported); approximately 35% of reported patients with the infection have died.

At first, the coronavirus that was first identified in Wuhan, China was called novel coronavirus (nCoV).  But on February 11, the United Nations health agency named it SARS-CoV-2.  “The name was chosen because the virus is genetically related to the coronavirus responsible for SARS,” the WHO explains.  “While related, the two viruses are different.”

But why is the virus different from the name of the disease? “Viruses, and the diseases they cause, often have different names,” the WHO states.  “For example, HIV (human immunodeficiency virus) is the virus that causes AIDS (Acquired Immune Deficiency Syndrome).  People often know the name of a disease, such as measles, but not the name of the virus that causes it, which is rubeola.”

According to WHO, there are different processes, and purposes, for naming viruses and diseases.  “Viruses are named based on their genetic structure to facilitate the development of diagnostic tests, vaccines and medicines,” the UN health agency explains. “Virologists and the wider scientific community do this work, so viruses are named by the International Committee on Taxonomy of Viruses (ICTV).”

Diseases are named to enable discussion on disease prevention, spread, transmissibility, severity and treatment. “Human disease preparedness and response is WHO’s role, so diseases are officially named by WHO in the International Classification of Diseases,” the WHO points out.

The WHO announced COVID-19 as the name of the disease caused by SARS-CoV-2, following guidelines previously developed with two other UN agencies: World Organization for Animal Health and Food and Agriculture Organization.

On March 9, WHO Director-General Dr. Tedros Adhanom Ghebreyesus, announced COVID-19 has spread to almost every country in the world.  Two days later, he declared it as pandemic in proportion.

“Pandemic is not a word to use lightly or carelessly,” Dr. Tedros pointed out.  “It is a word that, if misused, can cause unreasonable fear, or unjustified acceptance that the fight is over, leading to unnecessary suffering and death.”

According to Dr. Tedros, the pandemic is accelerating.  “It took 67 days from the first reported case to reach the first 100,000 cases, 11 days for the second 100,000 cases and just 4 days for the third 100,000 cases.” he said on March 23. “You can see how the virus is accelerating.”

Like most viruses, SARS-CoV-2 is not a living organism.  It is a protein molecule covered by a protective layer of lipid (fat) which, when absorbed by the cells of the ocular, nasal or buccal mucosa, changes their genetic code (mutation) and convert them into aggressor and multiplier cells, said an assistant professor in infectious diseases at Johns Hopkins University.

Since it is not a living organism, it cannot be killed but decays on its own.  Fragile was how the professor described the virus.  “The only thing that protects it is a thin outer layer of fat,” the professor said.  “That is why any soap or detergent is the best remedy, because the foam cuts the fat (this is the reason why you have rub so much: for 20 seconds or more, to make a lot of foam).  By dissolving the fat layer, the protein molecule disperses and breaks on its own.”

A study published of the peer-reviewed New England Journal of Medicine (NEJM) showed that the virus can remain “stable for several hours to days” on surfaces and in aerosols.  It said that people may acquire SARS-CoV-2 after touching contaminated objects.

The scientists who conducted the study found the virus is detectable for up to three hours in aerosols, up to four hours on cooper, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel.

Stability of the virus on such objects, however, is likely to depend on the humidity and temperature of the room, and other variables including air-conditioning, open windows and the general air quality.

“This virus is quite transmissible through relatively casual contact, making the pathogen very hard to contain,” Dr. James Lloyd-Smith, co-author of the study and a professor of ecology and evolutionary biology at the University of California, Los Angeles (UCLA). “If you are touching items that someone else has recently handled, be aware they could be contaminated.”

The US Centers for Disease Control and Prevention (CDC) said the virus could survive longer in nonporous surfaces that could include things like doorknobs, bus handrails, light switches, desks and keyboards.

“We don’t know how long the virus can live on a phone or a phone case,” said a Business Insider feature, “but researchers could speculate that because it’s smooth, non-absorbent surface, it’s possible that the survivability would be similar to plastic.”

But the good news is: the virus isn’t airborne.  However, it can linger in droplets on particles in the air.  In fact, the study found that viruses could last up to three hours in droplets on the air.

“(While the COVID-19 virus) can be detected in the air for 3 hours, in nature, respiratory droplets sink to the ground faster than the aerosols produced in the NEJM study,” explains Dr. Carolyn Machamer, a professor of cell biology whose lab at the Johns Hopkins School of Medicine has studied the basic biology of coronaviruses for years.  “The experimental aerosols used in labs are smaller than what comes out of a cough or sneeze, so they remain in the air at face-level longer than heavier particles would in nature.”

When it comes to COVID-19, “the old and the sick are the most vulnerable,” said Dr. Juliana C.N. Chan, of the Chinese University of Hong Kong.  But people with diabetes and other chronic medical conditions like cardiovascular disease (CVD) should not be discounted.

In fact, “there is evidence that diabetes may increase risk for infection from COVID-19 two- to threefold, independently of other medical problems, such as CVD,” said Medscape Medical News.

This must be the reason why Dr. Chan and other experts are calling for diabetes patients, those with CVD, and patients with other chronic medical conditions “to be extra vigilant in their efforts to avoid contact with the virus.”

Although most people survive COVID-19, the vulnerable are most likely to die from it.  “In serious cases of infection, the COVID-19 virus invades the cells that line the respiratory tract and lungs and enters the mucus, causing pneumonia,” the Medscape feature explains.  “Severe lung damage from pneumonia can result in acute respiratory distress syndrome (ARDS), which can turn can cause septic shock.”

ARDS and septic shock are reportedly the main causes of death from COVID-19. – ###

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