Abstract
The ongoing COVID-19 pandemic perpetuated by SARS-CoV-2 variants, has highlighted the continued need for broadly protective vaccines that elicit robust and durable protection. Here, the vaccinia virus-based, replication-defective Sementis Copenhagen Vector (SCV) was used to develop a first-generation COVID-19 vaccine encoding the spike glycoprotein (SCV-S).
Vaccination of mice rapidly induced polyfunctional CD8 T cells with cytotoxic activity and robust Th1-biased, spike-specific neutralizing antibodies, which are significantly increased following a second vaccination, and contained neutralizing activity against the alpha and beta variants of concern. Longitudinal studies indicated neutralizing antibody activity was maintained up to 9 months post-vaccination in both young and aging mice, with durable immune memory evident even in the presence of pre-existing vector immunity. This immunogenicity profile suggests a potential to expand protection generated by current vaccines in a heterologous boost format, and presents a solid basis for second-generation SCV-based COVID-19 vaccine candidates incorporating additional SARS-CoV-2 immunogens.
Competing Interest Statement
The authors declare the following competing interests: RGG, PW, LH, and JH are current or past employees of Sementis Limited. PE, TC, NP, LL, KD, and JH are named on a PCT patent application covering SCV-COVID19 vaccines (applicant: Sementis Limited; application number: PCT/AU2021/050274). PE, TC, NP, LL, GH, JZ, RGG, PW, LH, KD, and JH own stock or hold stock options. This research was conducted as a collaboration between UniSA and Sementis Ltd, with UniSA salaries and project support from funds provided by Sementis Ltd. AT declares no competing interests.
