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. 2021 Jan 8;9(1):33. doi: 10.3390/vaccines9010033

Figure 4.

Figure 4

Impact of coupling density on the humoral response of the M2e peptide on PapMV-N nanoparticles. (A) Various coupling densities (14%, 28%, 44%, and 83%) of the M2e peptide on the PapMV-N vaccine platform were generated. Coupling was visualized on SDS-PAGE (top panel). Lanes 5 and 6 correspond to uncoupled platform and sortase A, respectively. The proteins were transferred to a membrane for Western blotting with either anti-M2e (middle panel) or anti-PapMV (lower panel) antibodies. (B) Humoral response obtained using the same amount of platform with increasing amount of coupled M2e peptide. Balb/C mice, five per group, were immunized once via the intramuscular route (i.m.) with vaccine formulation buffer (Buffer), PapMV-N (10 µg) with 1 µg of free peptide M2e, or 10 µg of PapMV-N platform coupled to the M2e peptide with an efficiency of 14%, 28%, 44%, or 83%. ELISA analysis of serum harvested at day 20 was used to assess IgG2a titers directed to the M2e peptide. (C) Humoral response obtained when immunization was performed with the same amount of M2e peptide but with decreasing amounts of platform. Balb/C mice, five per group, were immunized once i.m. with the same amount of M2e peptide presented at different densities on the PapMV-N platform. The different groups of mice received formulation buffer as a negative control (Buffer), 10 µg of PapMV-N platform coupled with an efficiency of 14% (PapMV-C/M2e 14%), 5 µg of PapMV-N platform coupled with an efficiency of 28% (PapMV-N/M2e 28%), and 1.7 µg of PapMV-N platform coupled with an efficiency of 83% (PapMV-MN/M2e 83%). ELISA analysis of serum harvested at day 20 was used to assess IgG2a titers directed to the M2e peptide. ** p > 0.01, *** p < 0.001.