OVA-specific titers show a Th1-skewed antibody-mediated response.
Mice were vaccinated with treatment groups, including NP and soluble controls, normalized to OVA content. A mixture of NP, each containing antigen and presenting either MPLA or CpG, was administered to compare with MPLA/OVA+CpG NP to determine if PAMPs must be tethered for optimal responses. 21 days post-prime, mice inoculated with MPLA/OVA+CpG NP had the highest IgG1 titers (A) and significantly increased IgG2b (B) and total IgG titers (C) compared to NP with no adjuvant (−/OVA NP). The five-fold increase in IgG2b titers resulting from artificial bacteria NP versus soluble OVA, MPLA, and CpG suggests a NP-mediated Th1-skewed antibody-mediated response as IgG1 titers were lower. Interestingly, −/CpG+OVA NP groups also showed significantly higher anti-OVA total IgG compared to −/OVA-vaccinated animals, a result not recapitulated by CpG/OVA NP (C). A marker of nonspecific inflammation, elevated serum TNF-α levels over saline-injected mice was detected by ELISA (D). Serum TNF-α levels are highest in mice treated with exposed CpG (soluble or on NP surface) or alum and low in serum of mice vaccinated with CpG inside NP (MPLA/OVA+CpG and −/OVA+CpG).