How the COVID virus sneaks past the immune defenses

TUESDAY, December 28, 2021 (Health News) – How SARS-CoV-2 eludes man immune system it has baffled scientists for almost two years, but now they have discovered an important clue.

The virus that causes COVID-19 has been shown to have some hidden traits that allow it to spread from cell to cell, hiding from the immune system, discovers new research.

“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.

And, he added, this cell-to-cell transmission is not sensitive to antibodies from a previous infection or vaccination.

A new study compares SARS-CoV-2 with an earlier one coronavirus (SARS-CoV) caused by SARS 2003 outbreak of an epidemic, and sheds light on how viruses are spreading and resist the man immunity.

It also helps explain why the first epidemic led to a much higher death rate and lasted only eight months, while the current pandemic lasted two years with many asymptomatic cases – and no end in sight.

Experiments on cell cultures have shown that SARS-CoV-2 limits the release of particles that can be inactivated by a person’s antibodies. Like a disguised warrior, it remains tucked inside cell walls and spreads from one cell to another.

“SARS-CoV-2 can be effectively spread from cell to cell because there are essentially no host immune blockers,” Liu explained.

This known spiky protein on the surface of the virus allows it to spread from cell to cell. Neutralizing antibodies are less effective against the virus when it spreads to cells.

Comparing the two viruses, research has shown that the 2003 virus is more efficient in cell-free transmission. This is when free-floating viral particles infect target cells by binding to a receptor on their surface. This virus remained susceptible to antibodies produced by previous infection and vaccines.

However, the transmission of COVID-19 virus from cell to cell makes it difficult to neutralize it with antibodies.

For the study, the researchers used non-infectious pseudoviruses, with both types of spiky coronavirus proteins on their surface.

“The spike protein is necessary and sufficient to transmit SARS-CoV-2 and SARS-CoV from cell to cell because the only difference in these pseudoviruses were the spiky proteins,” said Liu, also director of the Virus and Pathogens Emerging Program Department at the Institute. for infectious diseases OSU.