SCIENTISTS have announced a potential vaccine against SARS-CoV-2, the new coronavirus causing the COVID-19 pandemic.
The paper was published by The Lancet, and is the first study to be published after critique from fellow scientists at outside institutions that describes a candidate vaccine for COVID-19.
"We had previous experience on SARS-CoV in 2003 and MERS-CoV in 2014. These two viruses, which are closely related to SARS-CoV-2, teach us that a particular protein, called a spike protein, is important for inducing immunity against the virus. We knew exactly where to fight this new virus," said co-senior author Andrea Gambotto, M.D., associate professor of surgery at the Pitt School of Medicine.
They tested the vaccine in mice. Delivered through a fingertip-sized patch it produces antibodies specific to SARS-CoV-2 at quantities thought to be sufficient for neutralizing the virus.
The vaccine which the authors called “PittCoVacc”, short for Pittsburgh Coronavirus Vaccine -- follows a more established approach, using lab-made pieces of viral protein to build immunity. It's the same way the current flu shots work.
The researchers also used a novel approach to deliver the drug, called a microneedle array, to increase potency. This array is a fingertip-sized patch of 400 tiny needles that delivers the spike protein pieces into the skin, where the immune reaction is strongest. The patch goes on like a Band-Aid and then the needles -- which are made entirely of sugar and the protein pieces -- simply dissolve into the skin. They said the needle patch is painless.
Scientists said the system also is highly scalable. The protein pieces are manufactured by a "cell factory" -- layers upon layers of cultured cells engineered to express the SARS-CoV-2 spike protein -- that can be stacked further to multiply yield.
Purifying the protein also can be done at industrial scale. Mass-producing the microneedle array involves spinning down the protein-sugar mixture into a mold using a centrifuge. Once manufactured, the vaccine can sit at room temperature until it's needed, eliminating the need for refrigeration during transport or storage.
When tested in mice, PittCoVacc generated a surge of antibodies against SARS-CoV-2 within two weeks of the microneedle prick.
Those animals haven't been tracked long term yet, but the researchers point out that mice who got their MERS-CoV vaccine produced a sufficient level of antibodies to neutralize the virus for at least a year, and so far the antibody levels of the SARS-CoV-2 vaccinated animals seem to be following the same trend.
They added that the SARS-CoV-2 microneedle vaccine maintains its potency even after being thoroughly sterilized with gamma radiation -- a key step toward making a product that's suitable for use in humans.
The authors are now in the process of applying for an investigational new drug approval from the U.S. Food and Drug Administration in anticipation of starting a phase I human clinical trial in the next few months.
"Testing in patients would typically require at least a year and probably longer," said co-senior author Louis Falo, M.D., Ph.D., chair of dermatology at Pitt's School of Medicine and UPMC.
The study was funded by the National Institute of Allergy and Infectious Diseases, National Institute of Arthritis and Musculoskeletal and Skin Diseases, and the National Cancer Institute. (University of Pittsburgh)