Figure 6. Lung viral loads of differentially immunized mice challenged intranasally with SARS-CoV on (A) day 3 post-challenge and (B) day 6 post-challenge.

In group 1, a formulation of 0.2 mg/mL RBD in 5 mg/mL Alhydrogel® with the dose of 20 μg/10 μg/10 μg of RBD for prime/1st boost/2nd boost was used for immunization, respectively. In group 2, the formulation 0.2 mg/mL RBD in 1.6mg/mL Alhydrogel® was tested, more specifically, a dosing regimen of 20 μg/10 μg/10 μg RBD for prime/1st boost/2nd boost was used while in group 3, 10 μg RBD were used for all three immunizations. Alhydrogel® alone and pre-formulated SARS-S protein (3 μg) were used in groups 4 and 5, respectively, as negative and positive controls