Coronavirus’ slow mutation could be good news for vaccine makers

CORONAVIRUS | The relatively slow mutation rate of the virus that causes Covid-19 could be good news for the various vaccines that are currently in development.

The SARS-CoV-2 virus - which causes the Covid-19 disease - uses a single strand of RNA to encode its genetic information, instead of DNA that is more stable and less prone to mutation.

Mutations can occur when the virus makes mistakes in making copies of its RNA, which is about 30,000 ‘letters’ long.

Despite this, the New York Times reported that SARS-CoV-2 is mutating slower than other RNA viruses because it has proteins that can act as ‘proofreaders’ to fix some of these mistakes.

“Each month, a lineage of coronaviruses might acquire only two single-letter mutations.

“In the future, the coronavirus may pick up some mutations that help it evade our immune systems. But the slow mutation rate of the coronavirus means that these changes will emerge over the course of years.

“That bodes well for vaccines currently in development for Covid-19. If people get vaccinated in 2021 against the new coronavirus, they may well enjoy a protection that lasts for years,” the New York Times reported in an explainer on how the virus mutates, and how researchers track such mutations to trace its spread across the world.

It said most mutations are known as ‘silent mutations’, meaning that it won’t change the amino acid it encodes for.

Non-silent mutations can alter a protein’s amino acid sequence, but changing a single amino acid in a protein usually has no effect on how the protein functions.

“Over time, viruses can evolve into new strains - in other words, viral lineages that are significantly different from each other.

“Since January, researchers have sequenced many thousands of SARS-CoV-2 genomes and tracked all the mutations that have arisen.

“So far, they haven’t found compelling evidence that the mutations have had a significant change in how the virus affects us,” the report said.

Family tree

Nevertheless, by comparing genetic sequences of different samples of the virus, scientists were able to reconstruct a family tree of the virus and trace its spread.

They found that the genomes of several samples from the initial outbreak in Wuhan have only a few mutations, which suggested that the virus has a recent common ancestor.

“Viruses accumulate new mutations at a roughly regular rate, so the scientists were able to estimate that the origin of the outbreak was in China sometime around November 2019,” the report said.

Last month, South China Morning Post reported that the first known Covid-19 case could be a 55-year old man in Hubei on Nov 17 last year, though Chinese doctors only realised they were dealing with a new disease on Dec 27.

For the record, the new disease was reported to the World Health Organisation (WHO) country office in China on Dec 31, 2019, though its cause was still unknown at the time.

The virus was only identified on Jan 7, 2020, and the first genetic sequence of the virus was published on Jan 12 to enable other countries, including Malaysia, to develop their own diagnostic tests for the virus.

According to the journal Nature, there are now more than 90 vaccine candidates in development that target the SARS-CoV-2 virus, though only a handful are likely to make the cut.

Some of these candidates use relatively new techniques that could expedite the development and manufacture of the vaccine in hopes of having it ready in 18 months, but these techniques have never been used in a vaccine approved for human-use before. - Mkini