There is yet another interesting discovery about the human body, one that backs recent Australian research: the immune system “remembers” the SARS-CoV-2 virus, thanks to new and ever-evolving antibodies produced in response to virus remnants hidden in the gut tissue.

And, say researchers from The Rockfeller University in New York, the quality of antibodies produced showed increased ability to block SARS-CoV-2 and its mutated versions such as the South African variant, even months after an infection.

Based on research by Michel C. Nussenzweig, Head of the Laboratory of Molecular Immunology at The Rockfeller University, and colleagues who have been continuously tracking and characterising antibody response in COVID-19 patients in the city, the immune system does not produce regular antibodies all the time, as previously thought.

It instead creates memory B cells, specifically those that produce antibodies against SARS-CoV-2. These cells can immediately recognise viral particles and will quickly unleash a new round of antibodies if they encounter it a second time.

Lab tests revealed the memory B cells had gone through numerous rounds of mutation even after a resolved infection, in some 87 patients, and as a result the antibodies produced were much more effective than the originals and latched on just as tightly to even mutated versions of the virus.

The patients’ memory B cells also did not decline in number as it normally would, and even slightly increased in some cases.

“We were surprised to see the memory B cells had kept evolving [like] in chronic infections, such as HIV or herpes, where the virus lingers in the body,” said Nussenzweig.

SARS-CoV-2 replicates in certain cells in the lungs, upper throat, and small intestine, and residual viral particles hiding within these tissues could be driving the evolution of memory cells. However, the researchers are uncertain as to whether these viral left-overs are still infectious or are simply the remains of dead viruses.

The discovery is nevertheless exciting – Nussenzweig said this type of immune response could potentially provide protection for quite some time, by enabling the body to mount a rapid and effective response to the virus, preventing re-infection.

Read: Antibodies produced in response to COVID-19 may trigger blood clots