Godzilla, Mothra, Giant Ants, The Fly, The Invisible Man, X-Men.
These are probably some of the images many of us think of when we hear that there is a new “mutant” virus arising in South Africa or Brazil. SCARY!!
But these new “mutant” viruses are not scary new organisms with new claws and super weapons. They are “natural” variants that ALWAYS arise. They raise some new issues, but they should not be seen as mortal threats.
I thought a short refresher on what these new strains are would be useful.
TRANSLATION ERRORS
Here is an example of how simple substitution or deletion errors in a string of letters can have little effect on the ability to understand the meaning of the sentence, or how some changes can have significant effects on the sentence created.
Consider the following sentence:
Due to the situation, and the cracked white board, we intend to purchase a new slate for the office.
Some “neutral” translation errors might occur when a monk copies it:
Do tp the situation, and the cracker white board, we intend to purchase a new slate for the office.
However, there may also be a “faulty” translation which changes the meaning of the sentence:
Do tp the situation and the cracker White Board, we intend to purchase a new slave for the office.
This is the way viruses mutate. They are not “intelligent”; they do “try” to mutate. They just make mistakes and those create new strains.
I have written in the past about how mutations occur. Here is a short recap: All of the cells in your body have a nucleus, a membrane-surrounded organelle inside which resides the DNA. When the DNA “wants” to send a message to the cell to make a protein, it generates an mRNA molecule by directly copying a section of the nucleotide string on the DNA and then that mRNA is exported into the cytoplasm of the cell. Mechanisms, enzymes, structures and other types of RNA (e.g., tRNA) then react with the mRNA and use ITS coded nucleotide string as a map to “write” the amino acid sequence of a new protein.
The mRNA does not reproduce in the cell. One copy from the nucleus is used to make a protein.
However, when an RNA virus such as COVID infects a cell, it needs to make multiple copies of its RNA in order to manufacture multiple new virus particles that will eventually be exported from the cell. We know that the viral RNA codes for the production of Spike proteins, but in order to make more RNA to include in the new virus particles, the viral RNA also carries the messages that are used to make two additional proteins. These two proteins are enzymes that allow for the replication of the viral RNA. Since there are no mechanisms inside the cell to provide this replication, the virus carries along its own toolbox to allow for replication.
BUT…these enzymes are not “perfect”. They replicate the RNA, but like a “pretty good” typist, they make occasional mistakes. So instead of replicating a piece of RNA with the absolutely same sequence of nucleotides (letters), they make one every once in a while, with a missing letter or a wrong letter.
Most of the time those errors are “neutral”; the change has little effect on the virus activity.
Sometimes, however, the error can result in a change that is significant. That change may be quite negative for the virus and may result in a viral protein that no longer works properly, thereby killing the virus. Those “mutants” simply never appear because they cannot reproduce or infect other cells. These are the most common errors, but since they die out, we simply never see them. On the other hand, the error might result in a viral Spike protein that actually binds better to cell receptors than the current strain. This virus would therefore be more contagious and would eventually replace the current strain. This is what we are seeing in the UK, SA and Brazil strains.
Sequencing viral isolates in the population allows us to follow the natural accumulation of mutations in a viral genome.
That is how we were able to determine whether a regional infection in the country had come originally from China, or from Europe. It is also how we were able to determine whether the original virus came from the bat population in China’s wet market, or the nearby laboratories.
Also, these “natural” variant mutations are how viruses that have resided in animal reservoirs suddenly acquire the ability to infect a new species. A mutation that allows a virus that existed in bats to now infect humans allows that virus to escape its bat reservoir and enter the human population.
From this I think you can understand that mutation in viruses is quite normal. New strains will appear. But, and this is the most important thing, those new strains will still look a lot like the previous ones. The vaccines will most likely work just fine although their measured effectiveness may be diminished. We should expect that the diminished effectiveness will coincide with a decreased lethality for those who have been immunized.
The biggest change that will occur is that the new, stronger binding Spike proteins will make contagion easier because the viral load necessary to establish an infection will most likely drop. This means the R0 will increase and that means that the percentage of the population needing to be immunized will rise. That is why you hear Dr. Fauci say that we may now need 80% of the population immunized where before we needed 75%.
The best way to fight the new variants is to immunize the population as quickly as possible. Random mutations occur at a fixed rate. The less people infected, the less virus being reproduced and the less chance for a new mutation.
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