They found that not only did the genomes differ from each other, but they were also very different from the genomes of the virus samples sequenced in Wuhan, China, the researchers wrote in a report that wasn't peer-reviewed but published on a forum on Feb. In fact, these mutations help scientists trace the steps of the virus, Grubaugh said.įor example, a group of researchers in Brazil recently isolated SARS-CoV-2 from two patients confirmed to have COVID-19 and sequenced the complete genomes of both samples of the virus. It's "unlikely that the developers have to worry about this." Once the vaccine is out, however, the virus could adapt to it and develop resistance, he said, but considering that other RNA viruses - such as those that cause measles, mumps and yellow fever - didn't develop resistance to vaccines, that scenario is unlikely. These viruses "are still so genetically similar that these mutations shouldn't alter a new vaccine," Grubaugh said. So, what does all of this mean for the development of a possible vaccine? Despite high rates of mutation among viruses in general, it's unusual to find viruses that change their mode of transmission between humans over such short time scales, he wrote. So, for a virus to become more severe or transmit more easily, multiple genes would have to mutate. Typically, multiple genes code for traits such as a virus's severity or ability to transmit to other people, Grubaugh wrote. Other mutations survive and get embedded into the "average" genome of a virus. If mutations are not beneficial to the virus, they are typically eliminated through natural selection, the mechanism of evolution whereby organisms better adapted to their environment tend to survive. "In reality, mutations are a natural part of the virus life cycle and rarely impact outbreaks dramatically." RNA viruses, or those that have RNA as their main genetic material instead of DNA, including SARS-CoV-2, mutate constantly and do not have the mechanisms to fix these "mistakes," as human cells do, for example.īut most of these mutations negatively affect the virus. The word mutation "naturally conjures fears of unexpected and freakish changes," he wrote. with the title "We shouldn't worry when a virus mutates during disease outbreaks." Knowing that such papers would come out during this outbreak, Grubaugh published a commentary in the journal Nature Microbiology (opens in new tab) on Feb. The authors of the paper acknowledge that the data in their study is "still very limited" and they need to follow-up with larger data sets to better understand how the virus is evolving, they wrote. When there's a rapidly growing local outbreak, scientists quickly sample the virus genomes from patients, resulting in the overrepresentation of some variants of the virus, Neher wrote. This statistical effect is probably due to early sampling of the L group in Wuhan, resulting in a "higher apparent" case fatality rates, he wrote. The finding that the coronavirus mutates into two strains with the L strain leading to more severe disease "is most likely a statistical artifact," Richard Neher, a biologist and physicist at the University of Basel in Switzerland, wrote on Twitter. Figuring out the mutations that a virus underwent worldwide takes "a nontrivial amount of effort and sometimes takes years to complete," he said. "It's a very small sample set of the total virus population," Grubaugh told Live Science. In addition, the researchers looked at only 103 cases. These slight changes likely wouldn't have a major impact, if any at all, on the functioning of the virus, so it would be "inaccurate" to say that these differences mean there are different strains, he said.
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