The identification of immunodominant linear epitopes of dengue type 2 virus capsid and NS4a proteins using pin-bound peptides.

We have used multi-pin peptide synthesis strategy to identify B-cell epitopes on two small dengue virus proteins, capsid and NS4a. We have identified several linear, immunodominant epitopes on both these proteins. Almost all these epitopes mapped to regions predicted to be hydrophilic based on Kyte and Doolittle profiles. Of the capsid epitopes identified in this study, the most immunogenic ones mapped to the C-terminal alpha4 helix, which lies on the solvent-exposed surface of the capsid dimer. The capsid epitopes were dengue-specific in that they could recognize antibodies in dengue virus-, but not yellow fever virus (YFV)- or Japanese encephalitis virus (JEV)-immune sera. This study has demonstrated the presence of anti-NS4a antibodies in dengue-patient sera definitively, for the first time, using authentic NS4a-derived pin-bound peptides as capture antigens. All the NS4a epitopes mapped to the amino-terminal third of the NS4a molecule. Our study suggests that the immunodominant epitopes of these two dengue proteins might have the potential to be used as a part of a recombinant multi-epitope protein containing carefully chosen E and NS1 epitopes for the detection of dengue infections with a high degree of sensitivity and specificity.