The antibody antibody of the previous vaccine may not be enough?Growing trend for novel omicron subvariants to evade antibodies
Time: November 24, 2022
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Three currently circulating omicron subvariants of SARS-CoV-2 are better at evading neutralizing antibodies produced by vaccines and infections than earlier versions of omicrons, two of which now account for reported COVID-19 cases in the U.S. Nearly 50% of -19 infections.
Three currently circulating omicron subvariants of SARS-CoV-2 — including two that now account for nearly 50 percent of reported COVID-19 infections in the U.S. — are better at avoiding vaccines than earlier versions of omicrons, new research shows and neutralizing antibodies produced by infection.
The scientists tested neutralizing antibodies against several circulating subvariants in serum samples from vaccinated, previously infected or recently infected healthcare workers. Three subvariants were significantly resistant to antibody immune responses: BQ.1, BQ.1.1 and BA.2.75.2.
According to the U.S. Centers for Disease Control and Prevention (CDC), BQ.1 and BQ.1.1 are subvariants of the BA.4/5 omicron variant that has dominated the U.S. for the past few months, each now accounting for about a quarter. BA.2.75.2, a variant of the BA.2 mutant, evades neutralizing antibody testing the best of all variants, but currently accounts for a very small percentage of the disease reported in the United States.
“Overall, the subvariants BQ.1 and BQ.1.1 are much better at evading enhancer-mediated antibody responses than previous variants—neutralizing antibody titers are clearly much lower. Both variants are become dominant,” said the study’s senior author Shan-Lu Liu, professor of virology in Ohio State’s Department of Veterinary Biosciences.
“It is important when traveling and gathering for the holidays to be aware that variants of SARS-CoV-2 continue to evolve, and if you received your first booster more than six months ago, you may consider a second booster dose, as the antibodies produced by a single booster may now be too low to be protective.”
The research was published in the journal Cell Host & Microbe.
While a third booster, a newer bivalent formulation, is being given to eligible people, more than 48 percent of the eligible population has yet to receive a booster dose, according to the Centers for Disease Control and Prevention. Liu’s lab had previously shown that the COVID-19 booster vaccine provided robust and broad antibody protection against a range of micron gene variants, while a second booster vaccine restored dwindling antibody numbers to protective levels.
In the current study, serum samples were obtained from healthcare workers who received two doses of the mRNA vaccine and a booster dose, or who were infected during an early or late omicron wave.
The results showed that the vaccine and single booster produced approximately 20-fold fewer antibodies that could neutralize BQ.1 and BQ.1.1 compared with neutralizing antibodies against the original or parental SARS-CoV-2 virus. Similarly, neutralizing antibody levels or titers generated during BA.1 small micron wave infection, antibody titers to the BQ subvariant were significantly lower than antibody titers to the parental virus, and BA.4/5 wave infection The antibody titers to BQ subvariation produced during this period did not reach the detection level.
“Our findings suggest that you cannot rely on natural infection to prevent the currently circulating Omega Clonal submutation.”
Liu and colleagues performed cell culture studies using a pseudovirus, a non-infectious viral core whose surface is surrounded by a different SARS-CoV-2 spike protein, whose structure matches known variants. The methods used to detect neutralizing antibodies in blood samples account for the varying levels of antibodies produced by individuals.
In the study, Ohio State University collaborator and co-author Kai Xu created structural models of the individual amino acids altered by the most recent mutations on the spike protein, identifying key molecules that rearrange some of the submutations so that they can block antibodies Bind to virus particles. The model revealed that one of these amino acids, called N460K, also enables BQ.1 and BQ.1.1 particles to enter host cells more efficiently and force host cells to fuse together, a step in viral infection that can increase pathogenesis Mechanism – This contributes to the onset of the disease, the progression to more severe symptoms, and the ability of the disease to spread.
“From my point of view, this is concerning because the original omicron variant wasn’t very pathogenic — it didn’t cause much cell fusion at all, but we’re now seeing new subsets of these cells with increased fusion. The tendency to mutate, which puts the virus in a better position to lead to infection and disease.”
Research by other labs on the production of neutralizing antibodies by bivalent enhancers suggests that newer enhancers will provide protection against new small particle subvariants, Liu said.
But Liu has already submitted a paper on another subvariant called XBB, a recombination variant that results from the exchange of genetic material between two small particle subvariants of BA.2, showing what he Said “extraordinary” resistance to neutralizing antibodies from vaccination and previous infection.
“This virus does unexpected things,” he said. “We still need to do a good job of monitoring and keeping a close eye on these emerging concerns.”
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