Figure 2.

Schematic representation of the experimental protocol in BALB/c and K18-hACE2 mice for the safety, immunogenicity, and efficacy assessment

For safety and immunogenicity assays (in the top side), 48 five-week-old female BALB/c mice were allocated to 6 groups (n = 8) and were injected intramuscularly with two doses of 0.1 mL of the PHH1-1V vaccine on days 0 (prime) and 21 (boost). Then, animals were monitored daily for clinical signs and bodyweight was recorded weekly until D35/D37, when they were euthanized and both spleens and blood were collected. For safety, immunogenicity and efficacy assays (in the bottom side), K18-hACE2 mice were allocated to 4 groups (efficacy against SARS-CoV-2 D614G) or 3 groups (efficacy against different VoCs), and were injected intramuscularly with two doses of 0.1 mL of the PHH1-1V vaccine on days 0 (prime) and 21 (boost). On D35 animals were challenged with 10³ TCID₅₀ of the SARS-CoV-2 or different VoCs, blood samples were collected to analyze neutralizing activity, and they were monitored daily for clinical signs and mortality. Then, challenged animals were chronologically euthanized on D37, D39 and D42/D43; and several tissue samples were collected for several analyses. Schematic artwork used in this figure is provided by Servier Medical Art under a Creative Commons Attribution 3.0 Unported License.