According to a recent Singapore study, the antibody neutralization activity of convalescent patients with the coronavirus illness 2019 (COVID-19) appears to be reduced against the B.1.1.7 and B.1.351 strains of SARS-CoV-2 due to changes in the virus's Spike protein.
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"While governments throughout the world are
working to get COVID-19 vaccinations to the bulk of the public as quickly as
possible," the researchers wrote, "it is of significant worry that
all presently licensed vaccines and those continuing in development are based
on the ancestral Spike sequence."
"Our findings have emphasized the critical need
to produce novel COVID-19 vaccines that are not solely based on the ancestral
Spike sequence," they said.
The neutralizing activity of 57 convalescent plasma
samples from COVID-19 patients was evaluated against live virus isolates of the
wildtype, B.1.1.7, and B.1.351. In comparison to the virus bearing the
ancestral Spike protein sequence, the samples demonstrated lower neutralizing
activity against both variations. [Vaccines 2021;6:125] [NPJ Vaccines
2021;6:125]
Plaque reduction neutralization test (PRNT) scores for
the 50-, 80-, and 90-percent cutoffs all revealed substantial declines. Such
decreases were more pronounced against the B.1.351 variety in all cases,
implying higher neutralizing activity attenuation.
The results of a neutralization assay against pseudo
viruses encoding Spike protein sequences from the wildtype, B.1.1.7, or B.1.351
strains were corroborated by these findings. While most patient samples could
still neutralize SARS-CoV-2 at high concentrations, activity against both nonwild
type variants was severely reduced.
The severity of the disease proved to be a significant
determinant in neutralizing action. Samples from COVID-19 patients with severe
disease displayed higher neutralizing potency against SARS-CoV-2 in both the
live virus and pseudo virus assays than samples from individuals with moderate
or mild sickness.
However, even after stratifying by disease severity,
plasma samples had considerably lower neutralizing activity against the B.1.1.7
and B.1.351 strains than the wildtype virus.
“The rapid spread of SARS-CoV-2 viral variants from
the United Kingdom and South Africa has raised significant concerns worldwide
about the degree of protection provided by humoral immune responses elicited by
natural infection or vaccination,” the researchers wrote, adding that some
studies have already shown significant reductions in anemia.
The current findings added to the increasing
literature on COVID-19 variations by revealing that the humoral immune
responses produced by the original outbreak in Singapore are less than those
elicited by emerging variants.