| dc.description.abstract | Few conserved epitopes from the Envelope (E) protein of the dengue virus have previously
been identified to show a broader immunogenicity and neutralization towards all the
fours dengue virus serotypes. Inclusion of an unnatural amino acid such as para-nitro
phenylalanine in the place of a phenylalanine in a protein, has previously been reported
to enhance the immunogenicity. The aim of this research was to explore the effect of
having para-nitro phenylalanine in the place of phenylalanine of those conserved E protein
epitopes in enhancing their immunogenicities. Therefore peptides representing these
epitopes, namely P1/E, P2/E, P3/E and P4/ E, were commercially synthesized with and
without the inclusion of a para-nitro group on phenylalanine. Three mice (Balb/c) batches
were immunized with each peptide. The immunogenicity of these peptides was studied,
by assessing the antibody levels generated against the corresponding peptide in collected
antisera. The whole E protein was used as a positive control and the adjuvant alone was
used as the negative control. All the peptides, with or without the modification, induced
antibodies in mice as measured using ELISA assays. Mean OD values of unmodified and
modified peptides are as follows; P1/E:0.390 ± 0.02a, P2/E:0.305 ± 0.01a, P3/E: 0.244 ±
0.02b, P4/E: 0.238 ± 0.01a, Mod-P1/E; 0.311 ± 0.01b, Mod-P2/E: 0.166 ± 0.02b, Mod-P3/
E: 0.371Âs0.03a, Mod-P4/E: 0.253Â ´ s0.01a. Out of the four peptides studied, P3/E with the ´
para-nitro phenylalanine modification (Mod-P3/ E), produced significantly high antibody
levels as compared to its unmodified version. Interestingly for rest of the peptides, there
were no significant differences in the levels of antibodies between the ones with and
without para-nitro phenylalanine. Accordingly, this study does not provide sufficient
enough evidence to support the claim that inclusion of an unnatural amino acid in the
place of a phenylalanine in a protein enhances the immunogenicity in the tested E protein
epitopes of the dengue virus. | |
