Researchers at the Pasteur Institute in France have found that the mutated SARS-CoV-2 coronavirus strain from South Africa has increased resistance to humoral immunity, which makes it more dangerous to humans. However, the South African strain is more resistant than the other mutated strain from the UK. This is reported in a preprint available in the bioRxiv repository.
Researchers have isolated strains B.1.1.7 (originated in the UK) and B.1.351 (South Africa) and determined their sensitivity to SARS-CoV-2 specific antibodies present in serum and nasal swabs of COVID-19 patients … To compare with the sensitivity of the original D614G strain, the scientists used reporter cells that synthesize a green fluorescent protein. After incubation with coronavirus overnight, cells added to the serum start to glow.
The results showed that B.1.1.7 was neutralized in 79 of 83 sera from recovered patients collected nine months after the onset of symptoms, which is almost the same for the D614G strain. However, in 40 percent of sera, the activity of antibodies against B.1.351 decreased or completely stopped. In addition, antibodies obtained from vaccinated people were also less effective against the African strain.
Humoral immunity is directed against pathogens in biological fluids of the body and is carried out through the production of antibodies by B-lymphocytes in the blood plasma.