Researchers, including Dr. Ryan Troyer from the University of Western Ontario, who is funded by the CITF, are developing a new vaccine that uses a harmless virus-based delivery vehicle. This approach enables the SARS-CoV-2 spike protein to be presented to the immune system, thereby training it to recognize and prevent SARS-CoV-2 infection. The vaccine candidate was demonstrated to be capable of providing protection from infection and significantly reduced lung inflammation, a hallmark of COVID-19, in animal models. The paper is published in PLoS Pathogens.

Key findings:

  • A COVID-19 vaccine was developed using a live virus as the delivery vector. The viral vector, called vesicular stomatitis virus (VSV), was modified to encompass the genetic instructions to make the SARS-CoV-2 spike protein, while being rendered harmless to humans. Vaccines using a modified VSV vector have successfully been used for other pathogens, such as Ebola.
  • Vaccination of mice with the VSV-based COVID-19 vaccine using two doses two weeks apart induced high levels of SARS-CoV-2 spike-specific IgG antibodies, neutralizing antibodies, and highly effective T-cell responses. The VSV-based vaccine was safe and did not elicit systemic immune reactions against the viral-vector.
  • Immunized mice were protected against infection, including severe illness and death, when exposed to the wild-type (or original) strain of SARS-CoV-2 four weeks after the second dose. Immunization was shown to considerably reduce lung damage from infection when compared to non-immunized infected mice.
  • The VSV-based candidate vaccine was also shown to be safe and protective in animal models. Blood samples evidenced neutralization of the wild-type SARS-CoV-2 virus as well as the Alpha, Beta, and Gamma variants of concern.

Kim GN, Choi JA, Wu K, Saeedian N, Yang E, Park H, Woo SJ, Lim G, Kim SG, Eo SK, Jeong HW, Kim, T, Chang JH, Seo SH, Kim NH, Choi E, Choo S, Lee S, Winterborn A, Li Y, Parham K, Donovan JM, Fenton B, Dikeakos JD, Dekaban GA, Haeryfar SMM, Troyer RM, Arts EJ, Barr SD, Song M, Kang CY. A vesicular stomatitis virus-based prime-boost vaccination strategy induces potent and protective neutralizing antibodies against SARS-CoV-2. PLoS Pathogens. 2021 Dec 16;17(12):e1010092. doi: 10.1371/journal.ppat.1010092