Ingenuity of a miniscule to savage the cerebral titan: how did the coronavirus disrupt modern society?
“One general law, leading to the advancement of all organic beings, namely, multiply, vary, let the strongest live and the weakest die.”
― Charles Darwin, The Origin of Species
At the beginning of 2020, we all were concerned about self-driving cars being tested somewhere in our west coast neighborhoods and expecting home deliveries to soon be performed exclusively by drones. The world was at the dawn of a digital metamorphosis, when suddenly the lights were quenched and the world goes off-course into unprecedented territory. This territory was seemingly dark, rough and made no sense to anyone. Suddenly the world stopped, and everything was stalled by a tinniest form of life called a virus. This particle doesn’t even have its own cellular machinery. It carries its genetic material wrapped in a protein shell and travels around the globe. We see for the first time in many of our lives a global pandemic. It seems like a perfect Hollywood movie plot, but it’s the reality we are living in today. Flabbergasted mankind is witnessing it unfold, yet unable to comprehend the nuances. How can the most superior species, the homo sapiens, succumb to the lowest, a virus? The answer lies in evolution, in the phrase “survival of the fittest”, in adaptability. While this virus named coronavirus or specifically SARS-COV2 (Severe Acute Respiratory Syndrome-Coronavirus 2) was making its way from bats to pangolins to humans, it evolved, it adapted. It’s shrewd and it has made silent strategic moves while we humans were running our lives, unaware that soon enough our lives would change dramatically.
Many laboratories are working throughout the world to unravel the very precise, the specific moves of coronavirus. Humans infected with coronavirus are affected primarily at three specific parts of the body: nose, gut and eyes. Why does the virus like these body parts and not others? If nostrils are nice wide-open tunnels to travel, then why not the ear canal? Here is the strategy. The coronavirus got its name because the outer protein shell of its body has spike like projections, and it uses these projections to gain entry into the human body. It is like having a key for a lock that has purposes other than letting the virus in. The names of these proteins aka locks are ACE2 and TMPRSS2. These proteins are specifically expressed by nasal, lungs, corneal and intestinal cells. Of course, they do have some complicated biology names like lung type II pneumocytes, ileal absorptive enterocytes and nasal goblet secretory cells. How did we find where in the body are these proteins present?
Scientists did experiments to study every single cell in these tissues of body obtained from donors. Many of us know about the concept of DNA from the popular ancestry tests. This unique bar code exists in every individual, half from mother and other half from father. Proteins are made from DNA through RNA, which is a close relative of DNA. The process of making RNA from DNA is called transcription and the next step, making protein from RNA is called translation. Scientists have decoded these processes in every single cell in tissue obtained from gut, cornea, nose and lungs and have recognized these cells that let the virus in. This virus is indeed a hacker!
In this superiority race, the human brain can decipher the moves of this virus. And then we discover the virus is smarter than we thought. It has affinity for ACE2 and TMPRSS2 for a reason, very selfish one. As the human body learns about this invasion by the virus, it rushes for its firearm. We have two types of immunity. One which is specific for a pathogen and it’s trained on memory and other one which in nonspecific ready to bombard on any intruder. It’s called the innate immune system. When the virus enters our cells, our immune system fires an anti-viral ammunition called interferon gamma. If we are armed with an antiviral, we should have gotten rid of it easily. However, this virus is cleverer, and has a master plan in this clash. It uses proteins ACE2 and TMPRSS2 to gain entry, human body spews interferons but this interferon cause more ACE2s and TMPRSS2s to express on more and more cells so that more and more viral particles gain access to the body. In retaliation to the anti-viral response, the virus keeps multiplying and proliferating in the body. Isn’t it ferocious? A tiny virus hijacks our machinery to gain access, to grow and when we attack it, it uses our firearm against us.
Can we simply block ACE2 and TMPRSS2 and let coronavirus wander with its then useless keys? It will be an ambitious prophylactic approach with its own repercussions as these two proteins, ACE2 and TMPRSS2, have additional roles in the human body. ACE2 ameliorates lung injury and TMPRSS2 is an essential protease. Masking them or shaving them off from cell surfaces will disrupt these other important functions. Hence is the race is on to search for better drugs and an efficacious vaccine. It's obvious then why it’s so challenging to design therapies for COVID-19 as popular interferon-based drugs will not help to treat this disease. As all the pieces of this new puzzle are studied in laboratories, we have our hopes high that there is an end to this dark tunnel, and we will soon have a therapy that will stop multiplication of the virus and alleviate the suffering. The virus was able to adapt and evolve, but we have the cerebral power to think, discover and innovate. The challenge is accepted and is being addressed piece by piece.
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Written by Navvy Kaur
Immunologist, Informatician, trying to learn some machine learning and grasp few mathematical concepts.