Figure 7.

Identification of immunogenic epitopes using overlapping peptides. (A) Sequence of the RBD and overlapping peptides (obtained from BEI Resources) used in ELISA. Amino acid residues located within the RBM are indicated in red text. Immunogenic epitopes are highlighted in colored boxes. (B) ELISA was done using serum samples (1:300 dilution) from mice immunized with Zn-chitosan, collected 6 weeks after the third immunization. Two hundred nanograms of peptides were coated in each well. RBD was used as a positive control. A negative control without any peptides is indicated as “Empty.” No immunoreactive peptides were identified using serum samples from Alhydrogel or Adju-Phos groups. Peptide numbers represent those from the 181-peptide array of the S protein. (C) Locations of the five most immunogenic linear epitopes are mapped onto the RBD structure (PDB: 6M0J).