Antibodies elicited by COVID-19 vaccination effective against delta
variant
Findings help explain why vaccinated people at low risk during delta
surge

Date:
August 17, 2021
Source:
Washington University School of Medicine
Summary:
Researchers have found that the delta variant of the virus that
causes COVID-19 is largely unable to evade antibodies elicited
by vaccination.

The findings help explain why vaccinated people have been at low
risk of getting seriously ill with COVID-19 despite a surge in
cases caused by the delta variant.



FULL STORY ========================================================================== Despite causing a surge in infections this summer that has resulted
in thousands of hospitalizations and deaths, the delta variant of
the virus that causes COVID-19 is not particularly good at evading the antibodies generated by vaccination, according to a study by researchers
at Washington University School of Medicine in St. Louis.


==========================================================================
The researchers analyzed a panel of antibodies generated by people in
response to the Pfizer COVID-19 vaccine and found that delta was unable
to evade all but one of the antibodies they tested. Other variants of
concern, such as beta, avoided recognition and neutralization by several
of the antibodies.

The findings, published Aug. 16 in the journal Immunity, help explain
why vaccinated people have largely escaped the worst of the delta surge.

In previous studies, co-senior author Ali Ellebedy, PhD, an associate
professor of pathology & immunology, of medicine and of molecular
microbiology, had shown that both natural infection and vaccination
elicit lasting antibody production.

But the length of the antibody response is only one aspect of
protection. The breadth matters, too. An ideal antibody response includes
a diverse set of antibodies with the flexibility to recognize many
slightly different variants of the virus. Breadth confers resilience. Even
if a few antibodies lose the ability to recognize a new variant, other antibodies in the arsenal should remain capable of neutralizing it.

"The fact that delta has outcompeted other variants does not mean that
it's more resistant to our antibodies compared to other variants," said co-senior author Jacco Boon, PhD, an associate professor of medicine,
of molecular microbiology and of pathology & immunology. "The ability of
a variant to spread is the sum of many factors. Resistance to antibodies
is just one factor.

Another one is how well the variant replicates. A variant that replicates better is likely to spread faster, independent of its ability to evade
our immune response. So delta is surging, yes, but there's no evidence
that it is better at overcoming vaccine-induced immunity compared to
other variants." To assess the breadth of the antibody response to
SARS-CoV-2, the virus that causes COVID-19, Ellebedy and colleagues -- including co-first authors Aaron Schmitz, PhD, a research specialist;
Jackson S. Turner, PhD, an instructor in pathology & immunology; and
Zhuoming Liu, PhD, a staff scientist -- extracted antibody-producing
cells from three people who had received the Pfizer vaccine.

They grew the cells in the laboratory and obtained from them a set of
13 antibodies that target the original strain that began circulating
last year.



==========================================================================
The researchers tested the antibodies against four variants of concern:
alpha, beta, gamma and delta. Twelve of the 13 recognized alpha and delta, eight recognized all four variants, and one failed to recognize any of
the four variants.

Scientists gauge an antibody's usefulness by its ability to block virus
from infecting and killing cells in a dish. So-called neutralizing
antibodies that prevent infection are thought to be more powerful than antibodies that recognize the virus but can't block infection, although
both neutralizing and non-neutralizing antibodies contribute to defending
the body.

The researchers found that five of the 13 antibodies neutralized the
original strain. When they tested the neutralizing antibodies against the
new variants, all five antibodies neutralized delta, three neutralized
alpha and delta, and only one neutralized all four variants.

"In face of vaccination, delta is relatively a wimpy virus," Ellebedy
said. "If we had a variant that was more resistant like beta but
spread as easily as delta, we'd be in more trouble." The antibody that neutralized all four variants of concern -- as well as three additional variants tested separately -- was called 2C08. In animal experiments,
2C08 also protected hamsters from disease caused by every variant tested:
the original variant, delta and a mimic of beta.

Some people may have antibodies just as powerful as 2C08 protecting
them against SARS-CoV-2 and its many variants, Ellebedy said. Using
publicly available databases, the researchers discovered that about 20%
of people infected or vaccinated against SARS-CoV-2 create antibodies that recognize the same spot on the virus that is targeted by 2C08. Moreover,
very few virus variants (.008%) carry mutations that allow them to escape antibodies targeting that spot.

"This antibody is not unique to the person we got it from," Ellebedy said.

"Multiple antibodies targeting this area have been described in
the literature; at least one is under development as a COVID-19
therapy. Similar antibodies have been generated by people infected
in Italy and people infected in China and people vaccinated in
New York. So it's not limited to people of certain backgrounds
or ethnicities; it's not generated only by vaccination or by
infection. A lot of people make this antibody, which is great
because it is very potent and neutralizes every variant we tested." ========================================================================== Story Source: Materials provided by
Washington_University_School_of_Medicine. Original written by Tamara
Bhandari. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Aaron J. Schmitz, Jackson S. Turner, Zhuoming Liu, Julian Q. Zhou,
Ishmael D. Aziati, Rita E. Chen, Astha Joshi, Traci L. Bricker,
Tamarand L. Darling, Daniel C. Adelsberg, Clara G. Altomare, Wafaa
B. Alsoussi, James Brett Case, Laura A. VanBlargan, Tingting Lei,
Mahima Thapa, Fatima Amanat, Trushar Jeevan, Thomas Fabrizio, Jane
A. O'Halloran, Pei-Yong Shi, Rachel M. Presti, Richard J. Webby,
Florian Krammer, Sean P.J.

Whelan, Goran Bajic, Michael S. Diamond, Adrianus C.M. Boon, Ali H.

Ellebedy. A vaccine-induced public antibody protects against
SARS-CoV- 2 and emerging variants. Immunity, 2021; DOI: 10.1016/
j.immuni.2021.08.013 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210817131425.htm

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