We are free to say that an inconceivable number of teams worldwide have been working on the treatment for COVID-19 since the first known emergence of this disease. When taken into consideration that top scientist and wealthy pharmaceutical companies are leading these research projects, one could ask how come we haven’t found a suitable treatment for COVID-19.
Genetic mutations in viruses
First, as you might know, all viruses contain genetic material. There are very unusual forms that a viral genetic material can take, such as single stranded DNA or double stranded RNA. When it comes to coronaviruses, their genome is a nonsegmeneted, single-stranded RNA molecule. Generally, RNA has a higher mutation rate when compared to a DNA molecule. This is because, usually, RNA proofreading mechanisms are lacking. Mutations happen because the machinery in the cell makes a mistake during replication. When this mutation is not noticed by proofreading mechanisms, it stays in a particular virus and it’s being passed down on its copies. Although mutations have a negative connotation, it’s the process that drives changes in the living organisms and that lead to evolution of human beings. Therefore, it’s absolutely natural.
What is the significance of mutations in SARS-CoV-2 evolution?
Coronavirus that causes COVID-19 is called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This virus has a gene that codes a protein with light proofreading activity, unlike many other RNA viruses, but in spite of this, it has a high mutation rate. Mutations ultimately serve to “make us better”, but only a small portion of changes in the genetic material of SARS-CoV-2 can lead to higher survival and reproduction of the virus. The most of mutations are actually bad for the virus itself as they limit its ability to reproduce and survive. SARS-CoV-2 is a highly contagious virus, so it replicates constantly in an enormous number of hosts which leads to a higher occurrence of mutations. If you have many mutations going on worldwide, there will be some rare positive ones which will lead to better survival and reproduction of the virus. Such changes lead to new variants of SARS-CoV-2. Mutations that create these variants are called fixed mutations because they successfully spread and prevail in a population. The more contagious the virus, the higher fixation rate is.
How is SARS-CoV-2 treated?
Viruses can’t be treated with numerous and basic antibiotics. They are treated with antiviral drugs. There is a huge difference among the mechanisms of these drugs. Antibiotics work in a manner that they attack a particular cellular component of bacteria that is not found in humans, so that this substance can specifically target the pathogen, not the host cells. However, using antiviral drugs is a bit tricky because viruses use the host cell machinery to replicate, which means that scientists have to design a drug that somehow interferes with the life cycle of a virus, but doesn’t interfere with the healthy cells of an infected individual. Most the antivirals work as nucleotide mimics. However, simple nucleotide mimics don’t work on SARS-CoV-2 because of the proofreading activity. The only currently approved antiviral drug for COVID-19 is remdesivir, an adenosine analogue (type of nucleotide mimic). This drug is administered intravenously which means it’s usually given when patients are hospitalized due to serious symptoms of COVID-19. Remdesivir isn’t helpful when it comes to very serious cases of this disease which lead to death, so it doesn’t significantly lower the mortality incidence. This happens because in this stage, the virus has made too much damage. Therefore, drug research teams need to focus on finding an effective medicine, but it also has to be easily administered. Right now, pharmaceutical companies are focusing on designing oral or inhaled medications for this illness. In this way, patients will be able to treat this infection in early stage which is crucial when it comes to antiviral therapies.
What is the perspective of finding a suitable treatment for COVID-19?
Ultimately, we can say that it’s a huge challenge to find a suitable treatment for COVID-19. The process of creating antiviral drugs is very complicated, since pharmaceutical companies have to start from the scratch. Natural antiviral substances are very rare, unlike antibiotics. Unfortunately, an additional challenge is that SARS-Cov-2 virus changes constantly. It’s a highly contagious RNA virus and, consequently, has a high mutation and fixation rate. Positive mutations of the virus could lead to emergence of new resistance mechanisms towards antiviral drugs. Resistance to drugs is a huge issue when it comes to any sort of microorganisms. However, antibiotics are numerous and a lot of research has been done on them. Antivirals, on the other hand, take a lot of time to be created and there aren’t many of them. If you take into consideration that creation of an antiviral drug can take years and that viruses, generally, change quickly, and can gain resistance to existing therapies, it is clear why the invention of therapy for COVID-19 is one of the biggest challenges our humanity has faced.
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