University of Pittsburgh School of Medicine’s COVID-19 Vaccine Candidate Shows Promise

Scientists from the University of Pittsburgh School of Medicine (Pittsburgh, PA, USA) have announced a potential vaccine against SARS-CoV-2, which when tested in mice, delivered through a fingertip-sized patch, produces antibodies specific to SARS-CoV-2 at quantities thought to be sufficient for neutralizing the virus.

In comparison to the experimental mRNA vaccine candidate that has just entered clinical trials, the new vaccine called PittCoVacc, short for Pittsburgh Coronavirus Vaccine, follows a more established approach, using lab-made pieces of viral protein to build immunity in the same way the current flu shots work. The scientists 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.

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 have not yet been tracked over the long term, but the researchers noted that the mice which received 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. Importantly, 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 is suitable for use in humans. The researchers were able to act quickly because they had already laid the groundwork during earlier coronavirus epidemics. The scientists are now in the process of applying for an investigational new drug approval from the US Food and Drug Administration in anticipation of starting a phase I human clinical trial in the next few months.

“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. “That’s why it’s important to fund vaccine research. You never know where the next pandemic will come from.”

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