Immunogenicity of virus-like particle vaccine candidates against SARS-CoV-2 infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to evolve, potentially leading to variants of concern that could become more transmissible, resist treatment, evade host immunity and reduce the effectiveness of currently available vaccines. Improved vaccines are still required as vaccination remains the most effective strategy against this virus. We have produced two SARS-CoV-2 virus-like particles (VLPs) using a baculovirus BacMam expression platform and examined their immunogenicity in mice. VLP1 contains the spike protein from the Wuhan strain, whereas VLP2 contains that of an Omicron variant. Mice immunized with VLP1 and boosted with VLP2 developed significantly higher antibodies in the sera, as well as higher numbers of IFN-γ secreting cells than the control group. Furthermore, both VLPs induced virus-neutralizing antibodies against Wuhan and Omicron variants. In conclusion, VLPs have the potential for the development of a safe and effective vaccine against SARS-CoV-2 variants.