COVID-19: No variants can escape human antibodies yet, though some can infect mice

Click to play video: 'COVID-19 variants threatening Canada’s progress in containing spread, Tam says'
COVID-19 variants threatening Canada’s progress in containing spread, Tam says
WATCH ABOVE: COVID-19 variants threatening Canada's progress in containing spread, Tam says – Mar 19, 2021

The following is a roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for COVID-19, the illness caused by the virus.

No variants escape all types of antibodies, so far

The human immune system makes many antibodies in response to COVID-19 infection or vaccination, and no single variant of the new coronavirus can yet escape all of them, according to a study posted on Thursday on bioRxiv ahead of peer review.

Researchers looked at how mutations in coronavirus variants affect antibodies’ ability to target a key region on the virus spike called the receptor binding domain (RBD), which has been mutating rapidly. In particular, the researchers studied three sets of antibodies that were classified by the structural features that affect their binding to the virus.

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Despite the diversity of antibodies, just one class dominates the antibody response that targets the RBD, they found. They also looked to see how many different classes of antibodies can be evaded by new coronavirus variants.

“Several lineages have mutations that reduce binding by two of the antibody classes, but so far no lineages have mutations that escape all three classes,” said coauthor Jesse Bloom of the Fred Hutchinson Cancer Research Center in Seattle. “We suggest this is an important thing to keep an eye on as the virus continues to evolve.”

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Coronavirus variants can infect mice

Some of the new coronavirus variants can cause COVID-19 in mice, researchers have found. The implications, such as whether mice could then transmit the virus to humans, will require further study, they said.

Click to play video: 'COVID-19 variants threatening Canada’s progress in containing spread, Tam says'
COVID-19 variants threatening Canada’s progress in containing spread, Tam says

The original virus strain identified in Wuhan, China, could not produce illness in mice because the spikes on its surface could not bind well to the ACE2 receptor protein on the animals’ cells. Some of the new concerning variants — particularly the ones first identified in South Africa and Brazil — have mutations that overcome this challenge, giving them the ability to infect and sicken the mice, researchers reported on Thursday on bioRxiv ahead of peer review.

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“This is indeed great news for animal studies to better understand the infection and disease as mice are widely available … to study many pathologies, and easier to work with than larger animals such as hamster or ferret,” said coauthor Etienne Simon-Loriere of Institut Pasteur in Paris.

Whether mice can transmit the virus to each other or to humans remains to be determined. “We do not have expertise to evaluate the health risk posed by this newly acquired capacity of SARS-CoV-2, but this is definitely something that will need to be done,” Simon-Loriere said.

“No one wants the virus to move to a new reservoir from where it could come back to humans, as was feared with mink farms, and hopefully it will not happen.”

Homeless patients in Boston benefit from recuperation unit

Homeless people needed to be hospitalized for COVID-19 less often after Boston Medical Center created a recuperation unit for them, according to a new report. Boston experienced a surge in cases during the spring of 2020, which disproportionately affected people experiencing homelessness and threatened to overwhelm hospital capacity.

As a response, the COVID-19 Recuperation Unit was set up near Boston Medical Center to provide isolation and quarantine space for homeless people who didn’t need hospitalization and were medically stable, saving hospital beds for patients with severe COVID-19. By the time the unit had been open for two months, the hospital saw a 28 per cent reduction in admissions of COVID-19 patients experiencing homelessness, researchers reported in JAMA Network Open. 

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COVID-19 social distancing and quarantining restrictions “were developed from the perspective of the ‘haves’ and not from the ‘have-nots,'” said coauthor Dr. Joshua Barocas of Boston University School of Medicine. “By re-centering the conversation on people experiencing homelessness, we can actually see that resources are needed in order to keep them and all of us safer.”

(Reporting by Nancy Lapid; Additional reporting by Carolyn Crist in Athens, Georgia; Editing by Bill Berkrot)

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