Scientists have discovered human antibodies which can neutralise several different Coronaviruses, paving the way for a pan-Coronavirus vacci...
Scientists have discovered human antibodies which can neutralise several different Coronaviruses, paving the way for a pan-Coronavirus vaccine. These antibodies have been detected in some people who recovered from Covid-19, a team at the University of Washington said.
The study, which has appeared in the journal 'Science', describes research on five such human monoclonal antibodies that can
cross-react with a number of beta-Coronaviruses.
The team examined certain memory B cells from
Covid-19 convalescent donors. Memory B cells are white blood cells that
recognise and respond to pathogens that have tried to attack the body during a
previous encounter.
Out of five promising antibodies that they
isolated, the scientists concentrated on one designated S2P6. Molecular
structure analysis and functional studies showed that this human monoclonal
antibody had impressive breadth: it was able to neutralize three different
subgenera of beta-coronaviruses. The scientists observed that it did so by
inhibiting the virus’ ability to fuse with cell membranes.
These antibodies target a structure, called stem
helix, in the spike protein of these viruses. The spike protein is critical to
the virus’ ability to overtake host cells.
The stem helix in the spike protein has remained
conserved during the evolution of certain coronaviruses. That means it is much
less prone to genetic changes and is similar in various coronaviruses,
explained lead author Dora Pinto, from the university’s School of Medicine in
Seattle.
These include those originating in bats that have
become dangerous pathogens in people, and another subgenus that causes a
serious human lung disease transmitted by dromedary camels, as well as a few
other subgenera that cause simple common cold symptoms.
The team went on to test if the S2P6 stem helix
antibody could protect against SARS-CoV-2 by administering it to hamsters 24
hours before exposure. They found that this antibody reduced the viral load of
SARS-CoV-2 by inhibiting entry of the virus and by enhancing additional anti-viral
and virus-clearing cellular immune responses.
Studies of the plasma from pre-pandemic human
samples, as well as from Covid-vaccinated and Covid-recovered individuals were
also analysed to see how frequently the stem-helix targeting antibodies appeared.
The highest frequencies occurred in people who had
recovered from Covid-19, then were later vaccinated. Overall, the data from
this study shows that while it does occur, it is relatively rare for SARS-CoV-2
to get plasma stem-helix antibody responses.
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