Over the past few weeks I’ve read so much about the disease COVID-19, and the Virus causing it, that ever so often I involuntarily run my hand through my hair, ploughing the surface of my head, to see if any spikes are beginning to protrude: if at all, they probably need to lock on to others, to spread the word. This is an attempt in trying to bring together all that I know, to grip the tiny nano fellow, and measure it up for a better understanding of the invisible enemy around us, in these pandemic times.
Throughout life on Planet Earth, Human Kingdoms face constant attacks from various villainous tribes of the Kingdom of the Bacteria and the Kingdom of the Virus for gaining precious territory within our skin-walled bodies, which are full of rivers of water, nutritious life-giving minerals and bountiful resources. Against these attackers we have a two-layer defence system integral to the Fort of our body. We also face life-threatening attacks from the external Kingdom of Animals, and our own human kind too, against which we have developed complex tools and an array of mechanisms, which we skilfully deploy on sight. That’s altogether another big story.
Coming back to the wonder that is our bodies, in the first layer of defence we have physical barriers: our skin, nasal hair, cilia; mechanism of clotting — a clot traps entry of pathogenic Bacteria & Viruses; the acid in our stomachs dissolves invaders who dare get that far inside; sweat glands — produce chemicals that kill Bacteria, etc.
If the enemy overcomes the first line of physical barriers, our second line of defence, the great Human Immune System, kicks-in. And the most common fearless man-hunting tribes appearing at the gates of our Immune System are, Bacteria and Viruses. There is nothing more fascinating than the Human Immune System, which has a stockpile of clever arsenal to recognise and outwit any stealthy trickster, getting past our quite versatile defences.
Bacteria are microscopic, simple, single-celled organisms having a cell wall and all the components necessary to survive and reproduce on their own, without much of outside help. Bacteria are one of the oldest living things on Earth, having been in existence for over 3.5 billion years. Less than 1% of bacteria cause disease. Take a deep breath and slowly move your hand to your belly-button: there are over 2,000 species of bacteria quietly living in that region. Say hello to them? Most are beneficial for our health: we might just call them FRIENDS, with some benefits.
Viruses are not considered to be living, in the true sense, because they require a host cell, a factory of machinery, stores of raw material supplies, and energy, to survive and to reproduce, which they cannot do on their own. Viruses typically consist of three key building blocks: RNA (Ribonucleic Acid), Proteins, and Lipids — which acts as a membrane, holding the various elements together. They have only one piece/strand of genetic material, either RNA or DNA (Deoxyribonucleic Acid), but not both. Viruses lack the capacity to independently read and act upon the information contained within the cells of our body — they simply hijack them. Most Viruses cause disease, that impairs our capabilities or, in some rare circumstances, knocks us out plain dead.
The Virus that causes COVID-19 is called the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-COV-2) and was first detected in humans about five months ago. This particular coronavirus has never before appeared in the Human Kingdom, hence the term ‘novel coronavirus’.
The coronavirus are a large group of viruses with RNA strands, and Scientists have identified hundreds of Viruses to date. They are mainly responsible for respiratory related illnesses. They are zoonotic, meaning they can spread from animals to humans, often through an intermediary animal, which they use as a kind of ladder, or a bridge to conquer a wealthy Kingdom. In the past 20 years there have been two coronavirus outbreaks in the World emanating from the animal (in these cases, Bats)-to-human transmission path: 1). SARS (Severe Acute Respiratory Syndrome) in 2002, and 2). MERS (Middle East Respiratory Syndrome) in 2012. In the case of SARS is it believed that the virus passed from bats to an intermediate animal host, the Civet Cat, before jumping to humans. In the case of MERS it is believed that the virus must have originated in bats and travelled through Camels before climbing on to humans. Studies have shown that bats are a natural reservoir for a wide range of coronaviruses (COVs): they are immune to them and remain unaffected. The COVID-19 disease causing coronavirus in believed to have made a leap-of-faith from bats to humans through an intermediary animal, a Pangolin, or perhaps even a Snake. Studies say that the Virus could not have latched itself on to a human cell protein, directly from the bats, hence the devious route. The investigation is still on and we should be knowing once Scientists have credible information.
The SARS-COV-2 Virus is a tiny-nano size (90 nanometers particle, billionths of a metre), technically called a Virion. It contains four different proteins and a strand of RNA, a molecule which, like DNA, can store genetic information as a sequence of chemical letters called Nucleotides. In this case, the stored information, the Virus Genome — the written code, is simply how to make proteins that the Virus needs in order to replicate or make ‘photo-copies’ of itself. (The Virus genome is less that 30,000 genetic letters long. Ours is over 3 billion).
The RNA is enclosed within a bilayer lipid (a kind of fat) coat which anchors the four proteins: the Spike Protein, the Envelope Protein, the Membrane Protein, and the Nucleocapsid Protein guarding the RNA. The frontline attacker — the cell gate battering ram — the Spike Protein, is like a crown (corona, in Latin, means crown) protruding from the lipid layer. These spikes help the virus to easily engage, hook-up and attach itself to target cells, as if on a blind date. The bilayer lipid coat breaks down easily (the chink in the armour) when it comes into sufficient contact with a solution of soap and water, which is why hand-washing is simple and effective in destroying the Virus — spilling its RNA contents into the drain, to be washed away. The Virus just falls apart. Soaps contain fat-like substances known as Amphiphiles, structurally similar to the lipids of the Virus. The soap molecule competes with the lipids in the Virus’s coat to replace, and to ultimately destroy them. The lipid layer is also soluble in alcohol, ether and chloroform, which is why hand-santizers can dissolve them too. Wow, that’s cool. Why worry about a cure when you can keep them out so easily?
Once attached to a target cell, the Virus fuses with the cell, shedding its lipid coat, and vomiting its RNA, which then releases a shopping list of instructions on how to build and assemble new Viruses. The Virus commandeers the body cell and uses the factory machinery and stores supply to manufacture more Viruses, before the body’s immune cells detect the intruders and raise an alarm. The smart Human Immune System is capable of producing neutralising Antibody proteins that are able to stick to the Virus-spike proteins, and prevent attachment to the target cells. Generating these antibodies — to spike the Spike Proteins of the coronavirus, is often the goal of protective vaccination.
Once infected, human body cells make the ultimate sacrifice, lay down their lives, and deliberately invite their own destruction by sending SOS signals for the Immune Response System’s ‘Rapid Action Commando Forces’, called T-Cells, to be deployed. T-cells are a type of Lymphocyte cell produced in the Thymus Gland (hence, T-Cell), that can recognise fragments of the virus displayed on infected cell surfaces. When the T-Cells arrive they start firing with all guns drawn, releasing a payload of toxic enzymes that kill the infected cell. This strategic martyrdom is organised by the Immune System to deprive the Virus of its replication factories and can lead to the reduction of viral load in the patient. It takes several days for antiviral T-cells to expand and antibodies to be generated. Here’s the silver lining: memory cells ensure that if we encounter the same Virus again, we can react immediately with pre-existing defences, and lots of wisdom. Once bitten, twice shy? Sars-Cov-2 being new to humanity so we have no protective immunological memory, at the moment. Vaccines prepared, using harmless parts of the Virus can help us build protective memory.
Now, going back to where the invasion starts. How does the Virus enter the human body? Importantly, the Virus cannot gain entry in to our bodies by itself — we have to let it in. Welcome coronavirus? Oh, No! The Virus enters the body through the nose, the mouth, or the eyes, spreads to the back of the nasal passage and to mucous membranes in the throat, attaching to the body cells that produce a protein called ACE-2 (Angiotensin Converting Enzyme). Bats have a similar protein, hence it maybe a familiar hunting ground for the coronavirus. A home away from home?
The Virus circulates through droplets in the air, spread by coughing or sneezing by an infected person, or the by droplets landing on surfaces, which then by our touch of hand gets into our mouth, nose or eyes. The Virus borne in the droplets can lie on surfaces, depending on the type, from a few hours to several days. Hence, masks can do a lot, prevent our hands from ourselves, and if unknowingly infected, curtail the throw of sneeze or cough from affecting others. Virus ridden particles are inhaled and come in contact with cells lining the throat and larynx. These cells of the body have large ACE-2 receptors on their surfaces.
Many people, called the Asymptomatics, don’t even notice they have got an infection and so go about their work, to their homes and public places, infecting others. Early symptoms are usually cough, fever shortness of breath, and look to be like Flu or Common Cold. Symptoms typically appear between 2 and 14 days after exposure.
Occasionally, the Virus can cause severe problems, when it is hungry for more space. This happens when it moves down the respiratory tract and infects the lungs, which are even richer in cells with ACE-2 receptors. Many of these cells are destroyed, and the lungs become congested with bits of broken cell. In such cases, patients will require treatment in the Intensive Care Unit of a Hospital. Even worse, in some cases, a person’s immune system goes into overdrive, attracting cells to the lungs in order to attack the virus, resulting in inflammation. And this inflammation prevents the lungs from being able to oxygenate the blood and remove carbon dioxide, which culminates with the patient gasping for air and suffering more serious illness. This process can run out of control, more immune cells pour in, and the inflammation gets worse. This is known as a ‘Cytokine Storm’. In some instances, this can kill the patient.
How do we detect the coronavirus in our bodies? Typically, a swab is taken from the nose or throat of a person as a sample and tested using a diagnostic test called The real-time RT-PCR (Reverse Transcription Polymerase Chain Reaction) Test, which is highly sensitive and can deliver a reliable diagnosis as fast as, in about three hours time, though Laboratories generally take between 8 and 12 hours, even days, to deliver a result. This is one of the most accurate methods available for detection of a coronavirus, and has a lower potential for contamination or errors as the entire process is done within a closed tube.
In order for the coronavirus to be detected early, Scientists convert the Virus RNA into DNA by a process called ‘Reverse Transcription’ (RT). They do this because the RNA is too fragile and difficult to study, and only DNA can be copied or amplified by an already well established process called, Polymerase Chain Reaction (PCR), for easy detection. Once the RNA is converted in to DNA numerous copies can be made quickly and accurately for a thorough analysis.
The other test is called the Rapid Antibody Test, which is a Sereology Test — where a blood sample is taken from a person and tested for any antibodies, created by the body to fight off the virus when it last visited, without a Visiting Card. Antibodies are brand new proteins, ‘Y’ shaped, manufactured by the body to out-wit and kill an intruder, it recognizes.
The Antibody Test measures the amount of Immunoglobulins (Ig), also know as antibodies, in the blood, actually three specific types called, IgG, IgM, and IgA. Briefly, IgG can enter tissues and fight infections and protects against long term infection, IgM, is the first to be made by the Immune System to fight a new infection, and IgA protects against infection of mucous membranes.
In the case of COVID-19, Doctors mainly look for IgM, which develops early in the infection stage and IgG which shows up after you have recovered. So, if you has lots of IgG you would be having some kind of an immunity from the new Virus. For how long? That’s yet to be determined.
The Antibody Test results can be made available in seconds, by the addition of a Reagent solution to the blood sample. A positive result means that a person has had been infected by the Virus in the past, and probably has the fire-power to prevent a repeat attack. This so-called immunity varies from Virus to Virus and may last from a few months to several years. That’s the wisdom of our bodies.
In summary, the RT-PCR Test can tell you whether YOU HAVE THE CORONAVIRUS and the Antibody Test can tell you whether YOU HAD THE CORONAVIRUS.
Finally, we have a fantastic Immune System, within a body of unbelievable powers, which should be treated with enormous respect and allowed to do its work. We should feed it well with a balanced diet of food, water and exercise, and a strong positive mind, so that when there is a clear and present danger, the chemicals of the body trigger hidden weapons and generate new ones to match the onslaught of new resourceful inside invaders.
Are we The Last Kingdom? Time will tell. Tomorrow is another day.
Disclaimer: The source of the information in this article is ‘hunted and gathered’ from various publications available in the public domain. And the sole purpose it to educate and provide a better understanding of the coronavirus, if not already. At the time of publication it is known that the novel coronavirus first emerged in Wuhan, in China, late last year and has since infected more than 4.4 million people and killed nearly 302,000 worldwide.