In a new study, researchers have isolated the smallest biological molecule to date that completely and specifically neutralizes the COVID-19 virus.
This antibody component, which is 10 times smaller than a full-sized antibody, has been used to construct a drug—known as Ab8—for potential use as a therapeutic and prophylactic against SARS-CoV-2.
The research was conducted by a team at the University of Pittsburgh School of Medicine.
The researchers report that Ab8 is highly effective in preventing and treating SARS-CoV-2 infection in mice and hamsters.
Its tiny size not only increases its potential for diffusion in tissues to better neutralize the virus but also makes it possible to administer the drug by alternative routes, including inhalation.
Importantly, it does not bind to human cells—a good sign that it won’t have negative side-effects in people.
The researchers say that Ab8 not only has potential as a therapy for COVID-19, but it also could be used to keep people from getting SARS-CoV-2 infections.
Antibodies of larger size have worked against other infectious diseases and have been well-tolerated, giving them hope that it could be an effective treatment for patients with COVID-19 and for protection of those who have never had the infection and are not immune.”
The tiny antibody component is the variable, heavy chain (VH) domain of an immunoglobulin, which is a type of antibody found in the blood.
It was found by “fishing” in a pool of more than 100 billion potential candidates using the SARS-CoV-2 spike protein as bait.
Ab8 is created when the VH domain is fused to part of the immunoglobulin tail region, adding the immune functions of a full-size antibody without the bulk.
One author of the study is John Mellors, M.D., chief of the Division of Infectious Diseases at UPMC and Pitt.
The study is published in Cell.
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