Addition
of CpG to RBD mRNA-CART elicits a stronger anti-RBD immunoglobulin
response and leads to earlier isotype switching. (A) BALB/c mice were
immunized intravenously with either 3 μg of RBD mRNA-CART (n = 5), 3 μg of RBD mRNA-CART plus 3 μg of CpG
(n = 5), 3 μg of CpG CART (n = 5), or Naïve untreated (n = 5) and boosted
on day 4 and day 8 after priming. (B) Serum levels of RBD-specific
IgGs from RBD mRNA-CART (black), RBD mRNA + CpG-CART (blue), CpG CART
(orange), and Naïve (red) mice were monitored over the course
of 60 days postpriming by ELISA. (C) On day 14 and day 60 after priming,
the distribution of IgG isotypes specific to RBD was analyzed using
antimouse IgG1 (blue), IgG2a (black), IgG2b (red), and IgG3 (gray)
monoclonal antibodies by ELISA. (D) On day 14 and day 60 after priming,
the absolute concentration of the anti-RBD IgG was evaluated. * = P < 0.05 unpaired Student’s t test (two-tailed). Data representative of 2 individual experiments.