UNIVERSITY PARK, Pa. — A researcher in Penn State's College of Agricultural Sciences is part of a team of scientists working to develop a unique COVID-19 vaccine that uses a bovine adenovirus as a safe and effective delivery vehicle.

With support from a nearly $3.9 million grant from the National Institutes of Health, the team aims to create a vaccine that will protect all segments of the population, especially older adults.

"Adenoviral vectors have emerged as a promising gene-delivery platform for a variety of therapeutic and vaccine purposes during the last two decades," said Suresh Kuchipudi, clinical professor of veterinary and biomedical sciences and associate director of Penn State's Animal Diagnostic Laboratory. "Historically, we have used human adenoviruses as platforms for vaccine delivery, but using a delivery system based on an animal adenovirus means that the human population will have no preexisting immunity to the vector, thereby improving its effectiveness."

Kuchipudi explained that human adenoviruses are widespread and can cause common illnesses such as cold-like symptoms, fever, sore throat, bronchitis, pneumonia, diarrhea and pink eye. As a result, most people may have preexisting immunity that could impact the efficacy of vaccines delivered via a human-adenovirus-based vector.

The team, which is led by Purdue University virologist Suresh Mittal and also includes immunologist Suryaprakash Sambhara from the Centers for Disease Control and Prevention, has adapted an adenovirus typically found in cattle to prevent it from replicating, which enhances safety. The researchers also modified the adenovirus to express a peptide that stimulates a robust immune response to influenza viruses in mice.

"Our preliminary work has revealed that this novel vaccine platform provides significantly higher levels of immunity compared to that of human adenovirus vectors," Kuchipudi said. "We hypothesize that immunization with this vector expressing relevant antigens of SARS-CoV-2 will strengthen an effective anti-COVID-19 immunity."

The researchers noted that because SARS-CoV-2 is a newly emerged virus for which humans have no previous immunity, any vaccine will have to be highly immunogenic to provide protection, particularly among older adults, whose immune systems naturally decline with age.

"This work suggests that the bovine adenovirus vector system could serve as an excellent delivery vehicle for the development of recombinant vaccines against emerging pathogens — for the elderly and other segments of the population," Kuchipudi said. "We believe this effort will yield an effective COVID-19 vaccine and could make a significant contribution to flattening the pandemic's trajectory and helping to manage its second wave."