Figure 6

Subcutaneous (SC) plus intranasal (IN) prime without boost elicits Th1 biased neutralizing anti-S and anti-N antibodies. (a) The study design is shown with groups for SC prime only, SC + IN prime only, and SC + IN prime with either an SC or IN boost, all n = 7. There was an untreated control group of n = 4. Prime dosing was on Day 0, boosts on Day 21, and euthanasia on Day 35. Shown are sera (b) anti-spike (S) antibodies by subclass (dilution 1:30); (c) percent inhibition in the surrogate neutralization assay with sera where > 30% (dashed line) is correlated with neutralization of virus; and (d) anti-nucleocapsid (N) antibodies (dilution 1:270). Lung homogenate (e) anti-S antibodies; (f) neutralization (30% is dashed line); and (g) anti-N antibodies (dilution 1:30 for anti-S and -N). (h) The IgG1a + IgG2b + IgG3/IgG1 ratios for anti-S and anti-N antibodies are shown for sera and lung; values > 1 (dashed line) indicate Th1 bias. The ratio is not represented for mice with very low antibody production. Statistical analyses performed using One-way ANOVA with Tukey’s post-hoc analysis comparing groups where *p < 0.05 and **p ≤ 0.01. Data graphed as the mean with SEM.