By Jonny Lupsha, Wondrium Staff Writer
Viruses mutate frequently, and many are no cause for concern. Viral mutations are often so subtle that they go by unnoticed. A new mutation of COVID-19’s delta variant has been identified.
Since the coronavirus emerged in late 2019, several variants of the virus have sprung up and been confirmed by scientists around the world. The alpha variant was first spotted in the United Kingdom and eventually gave way to the more dangerous delta variant, which originated in India. Now, a slight deviation from the delta variant—officially categorized as AY.4.2 and nicknamed the “delta plus” variant—accounts for 6% of infections in the U.K. and is still increasing.
Unlike the original delta variant, delta plus has not been designated a “variant of concern” by the World Health Organization, though it is being monitored. But where do all these mutations come from? In his video series What Darwin Didn’t Know: The Modern Science of Evolution, Dr. Scott Solomon, Associate Teaching Professor at Rice University, explained genetic mutations.
Mutation: Copy of a Copy of a Copy
DNA comes in four nucleotides or base pairs: adenine (A) and thymine (T) pair together, while cytosine (C) and guanine (G) pair together. Mutations in DNA come from mistakes made while the DNA copies itself.
Anyone old enough to have familiarity with photocopiers has likely experienced problems with them, and mutations are similar to those copying issues. Pages came out of the tray with spots, streaks, or lines on them, and there are the analogous examples with DNA mutations.
“Some mutations are minor, like having a C where there is supposed to be a G,” Dr. Solomon said. “Sometimes an entire stretch of DNA bases can get copied incorrectly. In other cases, the correct DNA bases are copied, but in the reverse order—there are lots of ways to make mistakes when copying DNA.”
Most major mutations lead to the copied organism’s death. However, some mutations really don’t have any positive or negative effect on the organism. This may happen, Dr. Solomon said, if a DNA base gets changed somewhere in the part of the genome that isn’t involved in protein coding.
“That’s because the three-letter DNA base code has 64 different possibilities—four times four times four—but those 64 possibilities specify only 20 different amino acids,” he said. “The DNA code for amino acids is redundant because more than one three-letter sequence codes for the same amino acid.
“For example, the sequences ‘ATT’ and ‘ATC’ both code for the amino acid isoleucine; so, a mutation that changes the third letter in the sequence from a T to a C won’t make any difference whatsoever for the gene’s function.”
The Selfish Genetic Mutation
Oddly enough, some genetic mutations are helpful to an organism. This is where things like COVID-19’s delta variant come into play.
“If an individual with a helpful mutation reproduces, then the mutation will be passed on,” Dr. Solomon said. “And if it is helpful in a way that leads to a slightly longer life, and most important, more surviving babies, then the mutation will become more common in later generations.”
The delta variant of the coronavirus is more infectious than its predecessor and can cause more severe illness in the unvaccinated. From the virus’s perspective, this means more surviving babies and a stronger existence for it. So the favorable mutation that became the delta variant populated and remains the dominant strain of the disease today.
“Mutation provides the source of variations, and as we’ve already learned, once there is variation, any differences among offspring will sort the variation like a sieve,” Dr. Solomon said. “The new varieties that are harmful don’t pass through as often to later generations, while the helpful varieties are more likely to pass through.”
The delta plus variant is being monitored by health organizations around the globe.