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Study Proposes a Live Attenuated SARS-CoV-2 Vaccine Candidate

In a new study published recently on Nature Communications, researchers engineered a live-attenuated SARS-CoV-2 vaccine candidate that could potentially be studied at biosafety level 2 for easier COVID-19 research and countermeasure development.

Researchers at the University of Texas Medical Branch used an infectious clone of SARS-CoV-2 and deleted certain proteins to create an attenuated virus that can weakly replicate without causing diseases. Immunization with such live-attenuated virus confers robust immune protection against wild-type SARS-CoV-2. After testing and comparing the efficacy of attenuated vaccines, results demonstrate that a lower dose immunization could still provide protection against the virus in animals.

“The attenuated vaccine candidate has the potential advantages of low cost, strong immunogenicity, and long immune durability,” said Dr. Pei-Yong Shi, lead author of the study and professor of the Department of Biochemistry & Molecular Biology. “This can potentially serve as a live-attenuated vaccine platform and a Biosafety level 2 experimental system.”  

For SARS-CoV-2, three reverse genetic systems have been previously developed by the UTMB team. The new system developed by Shi and his team has incorporated the strengths of the current three systems, in which several rounds of viral infection of cells can be accomplished at Biosafety level 2. 

The study also highlights a potential for a veterinarian vaccine. SARS-CoV-2 can infect a variety of animal species, among which cats, minks, raccoon dogs were reported to spread the infection to other animals of the same species and potentially spillback to humans.

“A live-attenuated vaccine may be useful for the prevention and control of SARS-CoV-2 on mink farms,” said Shi.