Fig. 2: Immunogenicity of CDO-7N-1 in hamsters.
Six- to eight-week-old Golden Syrian hamsters were inoculated with PBS or 105 PFU CDO-7N-1 i.n. in a volume of 50 µL. Serum was collected at day 12, 20, 40, 75 and 90 post-immunization for (a) PRNT assay (PRNT90) against WT SARS-CoV-2 and ELISAs targeting anti-spike protein S1 (b), S2 (c), RBD (d) and N protein (e) IgG. Dotted horizontal lines indicate the detection limit. Dots represent individual animals (n = 12, 24 and 6 for PBS, 12-day CDO-7N-1 and 20/40/75/90-day CDO-7N-1, respectively). Data are presented as box and whisker ± SD with the median indicated by a line across the box, maximum to minimum points from three independent experiments. **P < 0.01, ****P < 0.0001 using two-tailed unpaired Mann‒Whitney U test. At day 28 post-immunization, hamsters were challenged with 105 PFU WT-SARS-CoV-2 i.n in a volume of 50 µL. At day 5 post challenge (33 days post-immunization), nose (f, p = 0.1667, not significant) and BALF (g, p = 0.1667, not significant) were collected for plaque assay analysis. Nasal turbinate and lungs were collected for H&E analysis (h). Scale bar in panel = 100 µm. i Hamsters were inoculated with PBS, or 105 PFU CDO-7N-1 as described in (a). A second and third inoculation of 105 PFU CDO-7N-1 was given at 23 and 33 days post-initial inoculation. Serum was collected at various time points extending over more than one year for PRNT assay (PRNT90) against WT SARS-CoV-2. j–n Hamsters were inoculated intranasally with PBS or 105 PFU CDO-7N-1, and serum samples were collected on day 28 post-immunization (pre-challenge); followed by intranasal challenged with 105 PFU of WT-SARS-CoV-2. Serum samples were then collected on day 5 post-challenge (33 days post-immunization). The samples were used for PRNT assay against WT SARS-CoV-2 (j) and ELISAs targeting anti-spike proteins S1 (k), S2 (l), RBD (m), and N protein (n) IgG. Dotted horizontal lines indicate the detection limit. Dots represent individual animals (panels f, g, n = 5 and 4 for PBS and CDO-7N-1; panel i, n = 24 for PBS, for CDO-7N-1: day 12 n = 21, day 25, n = 23, day 35, n = 22, day 180, n = 10, day 259, n = 18, day 367, n = 9; panels j–n, n = 4). Data are presented as box and whisker ± SD with the median indicated by a line across the box, maximum to minimum points from three independent experiments. *P < 0.05; ns, not significant using two-tailed unpaired Mann‒Whitney U test.
