Chimeric SARS-CoV-2 vaccine vectors stably incorporating the functional glycoprotein of VSV

Respiratory viruses, such as SARS-CoV-2, remain a global medical challenge, highlighting the need for adaptable vaccine platforms that elicit broad immunity while allowing flexible antigen design. Building on our established envelope-deleted (ΔE) SARS-CoV-2 vaccine candidate, we engineered chimeric variants that stably express the glycoprotein of vesicular stomatitis virus (VSV-G) as a model antigen, with or without co-expression of the native SARS-CoV-2 spike protein. Both constructs were genetically stable and displayed functional VSV-G, as shown by expanded, ACE2-independent tropism. Cryo-electron microscopy confirmed the presence of heterologous glycoproteins on virions. In vivo, both chimeric viruses exhibited an excellent safety profile and induced antigen-specific humoral responses against the encoded glycoproteins in Syrian hamsters and K18-hACE2 mice. Together, these findings demonstrate stable genetic incorporation and display of a functional heterologous glycoprotein into a SARS-CoV-2 virion, supporting use of the ΔE SARS-CoV-2 backbone as a potential platform for viral vector engineering and heterologous antigen delivery.