Potential vaccine for COVID-19 generates immunity in mice: Study

Researchers have tested a potential vaccine for COVID-19 in mice, which when delivered through a fingertip-sized patch, produced an immune response specific to the novel coronavirus at quantities thought to be sufficient for neutralising the virus.

The study, published in the journal EBioMedicine, noted that when tested in mice, the PittCoVacc -- short for Pittsburgh Coronavirus Vaccine -- generated a surge of antibodies against the coronavirus, SARS-CoV-2, within two weeks of delivering it.

"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," said co-senior author Andrea Gambotto from the University of Pittsburgh in the US.

"We knew exactly where to fight this new virus," Gambotto added.

The scientists said, the vaccine described in the current study follows a more established approach, using lab-made pieces of viral protein to build immunity.

They said it works the same way as current flu shots.

In the study, the researchers also used a novel approach to deliver the drug, called a microneedle array, to increase potency.

They said 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.

According to the scientists, the patch goes on like a Band-Aid and then the needles, made entirely of sugar and the protein pieces, simply dissolve into the skin.

"We developed this to build on the original scratch method used to deliver the smallpox vaccine to the skin, but as a high-tech version that is more efficient and reproducible patient to patient," said co-senior author Louis Falo from the University of Pittsburgh.

"And it's actually pretty painless -- it feels kind of like Velcro," Falo said.

The scientists explained that the protein pieces are manufactured by a "cell factory" with layers upon layers of cultured cells engineered to express the SARS-CoV-2 spike protein which can be stacked further to multiply yield.

They explained that the spike protein is the portion of the virus on its exterior which it uses to enter host cells.

Purifying the protein also can be done at industrial scale, the study noted.

According to the scientists, mass-producing the microneedle array involves spinning down the protein-sugar mixture into a mold using a centrifuge.

Once manufactured, they believe the vaccine can sit at room temperature until it's needed, eliminating the need for refrigeration during transport or storage.

"For most vaccines, you don't need to address scalability to begin with," Gambotto said.

"But when you try to develop a vaccine quickly against a pandemic that's the first requirement," he added.

While the tested animals haven't been tracked long term yet, they pointed out that mice who got their vaccine for the closely related MERS coronavirus produced a sufficient level of antibodies to neutralize the virus for at least a year.

So far, the scientists said, the antibody levels of the SARS-CoV-2 vaccinated animals seem to be following the same trend.

The SARS-CoV-2 microneedle also vaccine maintains its potency even after being thoroughly sterilised with gamma radiation, which the researchers added is a key step toward making a product that's suitable for use in humans.

"Testing in patients would typically require at least a year and probably longer," Falo said.

"This particular situation is different from anything we've ever seen, so we don't know how long the clinical development process will take," he added.

The scientists believe based on recently announced revisions to the normal processes that they may be able to advance this faster.