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Global Health
June 16, 2020

Genetic Analysis Tracks SARS-CoV-2 Mutations in Human Hosts

JAMA. 2020;323(23):2363. doi:10.1001/jama.2020.9825

An analysis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genomes collected from more than 7500 patients worldwide has identified mutations in the virus that could aid in drug and vaccine development.

The researchers found that the virus’s genetic diversity in most countries is similar to what it is globally, suggesting that it was introduced repeatedly by many infected people in each country rather than by a “patient zero.” The analysis found 198 mutations that have occurred more than once, indicating that the virus is undergoing selective pressure as it adapts to its human host.

“Mutations in themselves are not a bad thing and there is nothing to suggest SARS-CoV-2 is mutating faster or slower than expected,” co-lead author Francois Balloux, PhD, of the University College London Genetics Institute, said in a statement. “So far we cannot say whether SARS-CoV-2 is becoming more or less lethal and contagious.”

In fact, the majority of the mutations are likely neutral or deleterious to the virus, the authors wrote. Some of the recurrent mutations might affect the response of human immune CD4+ cells, which activate B cells to make antibodies, and CD8+ T cells, which kill virus-infected cells. They also found recurrent mutations in genes encoding the virus’ spike proteins, which enable the virus to enter human cells.

“A major challenge to defeating viruses is that a vaccine or drug might no longer be effective if the virus has mutated,” Balloux said. “If we focus our efforts on parts of the virus that are less likely to mutate, we have a better chance of developing drugs that will be effective in the long run.”