How the COVID Virus Sneaks Past Immune Defenses

TUESDAY, Dec. 28, 2021 (HealthDay News) – Just how SARS-CoV-2 eludes the human immune system has mystified scientists for shut to 2 years, however now they’ve uncovered an necessary clue.

Turns out the virus that causes COVID-19 has some stealth strikes that enable it to unfold from cell to cell, hiding from the immune system, new analysis reveals.

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

And, he added, this cell-to-cell transmission is just not delicate to antibodies from prior COVID an infection or vaccination.

The new examine compares SARS-CoV-2 to an earlier coronavirus (SARS-CoV) that brought about the 2003 SARS outbreak, and it sheds gentle on how viruses unfold and resist an individual’s immunity.

It additionally helps clarify why the primary outbreak led to a lot increased loss of life charges and lasted solely eight months, whereas the present pandemic has endured for 2 years with many circumstances being symptom-free — and no finish in sight.

Cell tradition experiments confirmed that SARS-CoV-2 limits launch of particles that may be inactivated by an individual’s antibodies. Like a stealth warrior, it stays tucked inside cell partitions and spreads from one cell to a different.

“SARS-CoV-2 can unfold effectively from cell to cell as a result of there are basically no blockers from the host immunity,” Liu defined.

That acquainted spike protein on the virus’ floor allows the cell-to-cell unfold. Neutralizing antibodies are much less efficient towards the virus when it spreads by cells.

In evaluating the 2 viruses, analysis discovered that the 2003 virus is extra environment friendly at cell-free transmission. This is when freely floating viral particles infect goal cells by binding to a receptor on their floor. That virus remained weak to antibodies produced by earlier an infection and vaccines.

But the cell-to-cell transmission of the COVID-19 virus makes it tougher to neutralize with antibodies.

For the examine, researchers used non-infectious pseudoviruses, with each sorts of coronavirus spike proteins on their floor.

“The spike protein is necessary and sufficient for both SARS-CoV-2 and SARS-CoV cell-to-cell transmission because the only difference in these pseudoviruses were the spike proteins,” stated Liu, additionally a director of the Viruses and Emerging Pathogens Program in OSU’s Infectious Diseases Institute.