RESEARCH: A mutation undercuts the immune response to the COVID virus

NATURE

A mutation undercuts the immune response to the COVID virus 

A handful of mutations to SARS-CoV-2 can help it to escape the immune response mounted by a subset of infected people.

Researchers have identified thousands of mutations in SARS-CoV-2 samples, but the vast majority are unlikely to have much effect on the virus’s biology. To identify potentially important mutations, Jesse Bloom at the Fred Hutchinson Cancer Research Center in Seattle, Washington, and his colleagues studied antibodies against SARS-CoV-2 isolated from the blood serum of people who had recovered from COVID-19 (A. J. Greaney et al. Preprint at bioRxiv https://doi.org/ghr85d; 2021).

The team tested the antibodies’ response to samples of the virus’s spike protein. Each sample protein carried different versions of a region called the receptor binding domain (RBD), which recognizes host cells and is a major target for antibodies.

Of thousands of RBD mutations tested, only a few reduced the antibodies’ ability to bind tightly to the spike protein — a change that might also indicate a reduction in the antibodies’ ability to disable the virus.

But the effects varied substantially between people. The most consequential mutations, at a location called E484, caused a steep drop in the potency of some individuals’ antibodies. Coronavirus variants identified in South Africa and Brazil carry a mutation at the same spot.

The findings have not yet been peer reviewed.

Immune cells gone wild are tied to COVID lung damage

Some of the severe respiratory symptoms of COVID-19 seem to result from the activity of specific immune cells, which can cause long-term inflammation of the lungs.

Alexander Misharin at Northwestern University in Evanston, Illinois, and his colleagues examined fluid from the lungs of 88 people with severe pneumonia caused by SARS-CoV-2 infection (R. A. Grant et al. Nature https://doi.org/fqds; 2021). Most of these individuals had high numbers of a certain type of T cell, a class of immune cells, in their lungs. The researchers also found that nearly 70% of alveolar macrophages, a type of immune cell that is located in the tiny air sacs of the lungs, contained SARS-CoV-2. The cells harbouring the virus showed relatively high expression of genes involved in inflammation. ...