Dermatologists in the US have moved quickly to develop a potential vaccine against the COVID-19 virus based on delivery of recombinant subunit vaccine through the skin using a novel Microneedle Array (MNA).
In just a few weeks clinicians at the University of Pittsburgh School of Medicine have used their previous experience with a MNA vaccine against MERS-coronavirus to develop a vaccine that induces potent and long-lasting antigen antigen-specific immune responses against coronavirus in animals models.
“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,” says co-senior author Dr Andrea Gambotto.
However they caution that a vaccine for human use may still take a year to complete efficacy and safety trials.
In a paper published in the EBiomedicine journal they describe how they used the novel microneedle array, a fingertip-sized patch of 400 tiny needles that delivers the spike protein pieces into the skin.
The patch is applied like a Band-Aid and then the needles — which are 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 Dr Louis Falo, professor and chair of dermatology at Pitt’s School of Medicine and UPMC.
“MNA delivered MERS-S1 subunit vaccines induced potent and long-lasting antigen antigen-specific immune responses,” the authors write.
“Notably, MNA delivery of these vaccines generated significantly stronger immune responses than those administered by traditional subcutaneous needle injection, indicating the improved immunogenicity by skin-targeted delivery.”
The dermatologists say their vaccine uses a conventional approach of using viral protein to build immunity, unlike the experimental mRNA vaccine candidate that just entered clinical trials,
And they claim their system also is highly scalable because the viral 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 mould 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.
“For most vaccines, you don’t need to address scalability to begin with,” Dr Gambotto says. “But when you try to develop a vaccine quickly against a pandemic that’s the first requirement.”
The authors are now in the process of applying for an investigational new drug approval from the FDA in anticipation of starting a phase I human clinical trial in the next few months.