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December 30, 2021

Study explains how COVID-19 beats immune defenses

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By Sola Ogundipe

HOW the  SARS-CoV-2 eludes the human immune system has mystified scientists for close to two years, but now they’ve uncovered an important clue.

It turns out the COVID virus  has some stealth moves that allow it to spread from cell to cell, hiding from the immune system, new research reveals.

“It’s basically an underground form of transmission,” said study author Shan-Lu Liu, of the Center for Retrovirus Research at Ohio State University in Columbus.

This cell-to-cell transmission is not sensitive to antibodies from prior COVID infection or vaccination.

The new study compares SARS-CoV-2 to an earlier coronavirus (SARS-CoV) that caused the 2003 SARS outbreak, and it sheds light on how viruses spread and resist a person’s immunity.

It also helps explain why the first outbreak led to much higher death rates and lasted only eight months, while the current pandemic has persisted for two years with many cases being symptom-free — and no end in sight.

Cell culture experiments showed that SARS-CoV-2 limits release of particles that can be inactivated by a person’s antibodies. Like a stealth warrior, it stays tucked within cell walls and spreads from one cell to another.

“SARS-CoV-2 can spread efficiently from cell to cell because there are essentially no blockers from the host immunity,” Liu explained.

That familiar spike protein on the virus’ surface enables the cell-to-cell spread. Neutralizing antibodies are less effective against the virus when it spreads through cells.

Researchers also found that the COVID-causing virus is better able to fuse with a target cell membrane, another key step in the process.

Better fusion, but not too much, is a key reason for its efficient cell-to-cell transmission. Too much can actually interfere with cell-to-cell transmission.

Vanguard News Nigeria