As Lindner explains, “The scaffold is roughly the size of a coronavirus and with coronavirus proteins attached to it, it looks a lot like SARS-CoV-2. Yet it cannot replicate, so you don’t have the safety concerns that come with a live attenuated virus.”
A virus-like particle that mimics SARS-CoV-2
At the College of Medicine, a team led by Nick Buchkovich, associate professor of microbiology and immunology, and Leslie Parent, is also developing a virus-like particle (VLP), a non-infectious particle that resembles a virus — another way of tricking the immune system into eliciting a response. In this case, the VLP expresses the SARS-CoV-2 surface proteins. Buchkovich, a virologist who studies human cytomegalovirus, a type of herpes virus that causes congenital birth defects, said the team hopes their vaccine will provide longer-term immune protection than many others in development.
A problem with some of the current vaccines being developed, he said, is that they use only the S protein, and studies suggest the structure of the S may vary depending on whether it is expressed alone or in segments. Using the S protein in the context of a VLP will allow for it to maintain the interactions with other viral proteins and have a structure similar to what is seen by the immune system.
The researchers are currently working to optimize and scale up the production of their VLPs and are starting to test them in mice.
“In mice, we know we get a robust antibody response, which is good, but we’re still working on analyzing the T-cell and B-cell responses, which we know will be critical for getting longer-term protection,” said Parent, an expert on retroviruses. “If we get good data in animals, we will begin to look for industry partners to help us take the vaccine to clinical trial.”
An “aerogel” to deliver nucleic-acid-based vaccines
Of the various vaccine types in clinical use, vaccines based on nucleic acid, including DNA and RNA, are among the easiest to develop and produce, and they induce a wide range of immune response types, thereby providing robust protection.
“Unfortunately,” said Scott Medina, assistant professor of biomedical engineering, “nucleic-acid-based vaccines have, until recently, not been widely adopted because they are rapidly degraded by enzymes in the body and they are not readily taken up by host cells.”