Fig 1: Evaluation of systemic antibody responses following i.n. immunisation.(a) Female 6-week-old WT BALB/c mice were primed and boosted 4 weeks apart via.the i.n. route with 10 µg of recombinant SARS-CoV-2 S formulated with adjuvant. Animals were bled periodically. (b) Weight of animals was monitored daily for the first week post-prime. S-specific IgG endpoint titres (EPT) in serum were evaluated at (c) week 3 and (d) week 9 via direct ELISA. At the terminal timepoint, serum S-specific (e) IgG1, (f) IgG2a and (g) IgA were measured. ELISA data are represented as median, with dots representing biological replicates (n = 8; data are pooled from two independent experiments, as denoted by circle and square dots). Statistical significance was determined via Kruskal-Wallis test combined with Dunn's multiple comparison test. p-value denotations: *p < 0.05, **p < 0.01 and ***p < 0.001.