June 10 (UPI) -- University of Florida researchers on Wednesday announced plans to repurpose a gene therapy approach used to treat rare neuromuscular diseases for a potential vaccine against COVID-19.
The approach being explored at the university involves injecting an adeno-associated virus, or AAV, for the new coronavirus into people. This is essentially a gene from harmless SARS-CoV-2, the new coronavirus that causes COVID-19, that will block harmful versions of it from entering human cells, researchers said.
In the past, AAVs have been used to treat rare neuromuscular disorders, including muscular atrophy in children, the researchers said.
They said they hope to begin clinical trials of the vaccine candidate in humans later this year and remain optimistic they can use the injection to fight future strains of SARS-CoV-2 as they develop.
"This is a virus that can change very rapidly, [which] is concerning because it means any vaccine made today may be ineffective tomorrow," Dr. Barry J. Byrne, a rare disease research and pediatrician at the school, said in a press release.
At present, at least 10 potential COVID-19 vaccines are in clinical trials, with dozens of others in development, according to the World Health Organization.
The University of Florida gene therapy vaccine can't replicate on its own, but is potent enough to trigger a beneficial, antivirus response from the immune system, according to Byrne and his colleagues, who are working in the school's Emerging Pathogens Institute.
Results from preclinical studies intended to determine whether the AAV vaccine can trigger virus-neutralizing antibodies against live SARS-CoV-2 are expected later this month. Early studies in animals have confirmed the vaccine starts to work quickly and remains in the system longer than many other single-dose injections.
The team is ready to assess the effectiveness and toxicology of two closely related vaccine candidates in rodents, which will pave the way for human trials, Byrne said.
He said he hopes to start a 12-month, multi-arm Phase I/II study to assess the vaccines' single-dose safety and effectiveness in 100 adult volunteers, with an emergency-use authorization requested from the U.S. Food and Drug Administration.
The AAV approach has some potential advantages over traditional vaccine development, said Byrne, who is director of the university's Powell Gene Therapy Center.
In addition, researchers likely won't have to spend as much time establishing AAV's safety -- given that the effective dose for a vaccine is thousands of times less than in a genetic disease -- because the approach has been evaluated in multiple clinical trials for other diseases.
Byrne and his colleagues also aim to develop a universal vaccine for future SARS-CoV-2 strains, an important consideration given that multiple mutations -- changes in the virus's genetic sequence -- have been documented by scientists.
They plan to develop a library of various "spike" proteins that the coronavirus uses to invade human cells -- a process that could take 18 months, according to the researchers.
While no licensed vaccines use AAV, about 25 so-called viral vector vaccines are in various stages of development around the world, Byrne said.
An AAV vaccine could be produced for only a few dollars per dose, although producing it in large may be challenging, he said.