A team of scientists in the U.S. and Netherland conducted a recent study that revealed that while severely affected people with Covid are hospitalized and vaccinated, people can neutralize the P.1 and the B.1.1.7, B.1.351 variants of severe acute respiratory syndrome coronavirus 2. But people who are with less severe Covid and are non hospitalized remain susceptible to these viral variants.
With 171.3 million confirmed Covid cases and 3.5 million deaths, it has become the largest pandemic in modern times. In addition, novel SARS-CoV-2 variants frequent emergency is continuously putting the global population under serious threat. Because of significantly increased immune evasion ability and infectivity, some viral variants have been designed by WHO as the Variants of Concern (VOCs).
Among recognized VOCs, B.1.1.7 (U.K.), B.1.351 (South Africa), and P.1 (Brazil) have been identified. However, these variants have started spreading globally soon after emerging, and cases with these variants have been detected in 132, 82, and 52 countries, respectively. In all three VOCs, the N501Y mutation in the spike RBD is a standard feature. The RBD affinity for human ACE2 is increased by this mutation, explaining the increased infectivity of these VOCs. In addition, the E484K mutation found in P.1 and B.1.351 variants facilitates viral escape from antibody-mediated neutralization.
The immune escape abilities of P.1, B.1.351, B.1.1.7 scientists have compared in the current study. Next, the scientist will investigate whether these VOCs can escape neutralization by polyclonal antibodies and monoclonal therapeutic antibodies from vaccinated people and Covid patients.
For antibody testing, from 69 Covid patients, 4 – 6 weeks after the symptom onset, serum samples were obtained. In addition, another set of serum samples were collected from 50 vaccinated healthcare workers four weeks after the 2nd vaccine dose. The participants received the mRNA-based Covid vaccine developed by Pfizer/BioNTech. The spike protein of wild-type three VOCs and SARS-CoV-2 were generated and collected serum samples used to measure the binding antibody responses using multiplex protein microarray. In addition, three VOCs and lentiviral-based pseudoviruses of the wild-type virus were utilized to determine the neutralizing ability of sera.
According to the study findings compared to the wild type SARS-CoV-2, for the B.1.1.7, B.1.351, and P.1 variants, the spike binding ability of convalescent sera reduced by 2.4-fold, 3-fold, and 4-fold, respectively. In addition, highly significant spike-binding antibody levels were observed between mildly affected non-hospitalized Covid patients and severely affected hospitalized, Covid patients. Binding antibody comparable level was observed in hospitalized patients and vaccinated people, 4 – 11 times higher than non-hospitalized patients.
Regarding virus neutralization, about 100% of vaccinated sera and about 96% of convalescent sera exhibited complete neutralizing ability against the wild-type virus. However, a significant reduction in neutralization potency of all tested sera showed against the VOC.