Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.11.245704v1?rss=1 Authors: Kuo, T.-Y., Lin, M.-Y., Coffman, R. L., Campbell, J. D., Traquina, P., Lin, Y.-J., Liu, L. T. C., Cheng, J., Wu, Y.-C., Wu, C.-C., Tang, W.-H., Huang, C.-G., Tsao, K.-C., Shih, S.-R., Chen, C. Abstract: The COVID-19 pandemic caused by the novel coronavirus SARS-CoV-2 is a worldwide health emergency. The immense damage done to public health and economies has prompted a global race for cures and vaccines. In developing a COVID-19 vaccine, we applied technology previously used for MERS-CoV to produce a prefusion-stabilized SARS-CoV-2 spike protein by adding two proline substitutions at the top of the central helix (S-2P). To enhance immunogenicity and mitigate the potential vaccine-induced immunopathology, CpG 1018, a Th1-biasing synthetic toll-like receptor 9 (TLR9) agonist was selected as an adjuvant candidate. S-2P was combined with various adjuvants, including CpG 1018, and administered to mice to test its effectiveness in eliciting anti-SARS-CoV-2 neutralizing antibodies. S-2P in combination with CpG 1018 and aluminum hydroxide (alum) was found to be the most potent immunogen and induced high titer of spike-specific antibodies in sera of immunized mice. The neutralizing abilities were measured with pseudotyped lentivirus reporter or live wild-type SARS-CoV-2 with reciprocal inhibiting dilution (ID50) titers of 5120 and 2560, respectively. In addition, the antibodies elicited were also able to neutralize pseudovirus containing the spike protein of the recent dominating variant D614G. A marked Th-1 dominant response was noted from cytokines secreted by splenocytes of mice immunized with CpG 1018 and alum. No vaccine-related serious adverse effects were found in the dose-ranging study in rats administered single- or two-dose regimens. These data support continued development of CHO-derived S-2P formulated with CpG 1018/alum as a broadly protective candidate vaccine to prevent COVID-19 disease. Copy rights belong to original authors. Visit the link for more info