Linear epitope mapping in the E and NS1 proteins of dengue and Zika viruses: prospection of peptides for vaccines and diagnostics GA_DZ_V1

Dengue and Zika are two mosquito-borne diseases of great concern, affecting mainly the tropical and subtropical regions worldwide. The arrival of Zika virus (ZIKV) in dengue virus (DENV) endemic areas imposed challenges for differential diagnosis and the development of candidate vaccines. The use of peptides has shown great potential to achieve these goals. We aimed to identify the linear epitope profile recognized by the serum samples of dengue and Zika patients in the E and NS1 proteins of DENV and ZIKV to select peptides with the potential for the development of diagnostic tests and vaccines. Analysis of a peptide microarray platform with serum samples of dengue and Zika patients demonstrated that the epitopes were evenly distributed across the entire viral proteins, showing no preference for particular regions. However, several epitopes were within epitope hot spots constituted by clusters of peptides recognized in more than 30% of the sub-arrays analyzed with individual or pools of serum samples. The serum samples of dengue and Zika patients showed a high level of cross-reaction for epitopes in the DENV and ZIKV proteins. Analysis of an additional peptide microarray platform containing selected peptides based on the results of the first screening showed that three peptides (DENV: TQGEPSLNEEQDKRF and TQTVGPWHLGKLEID; ZIKV: LELDPPFGDSYIVIG), highly specific for their cognate viruses (p<0.05), were within the epitope hot spots; however, these peptides showed low detection rates (32.5, 35.0, and 28.6%, respectively). We also found two peptides (DENV: WEVEDYGFGVFTTNI and LELDFDLCEGTTVVV) in the epitope hot spots detected by both dengue and Zika patients with similarly high rates (arbitrary detection rate cut-off threshold of ≥40%). The epitope hot spots harbor several immunodominant epitopes recognized by a higher number of individuals when compared to the 15 aa sequence peptides. Therefore, the entire epitope hot spots, spanning up to ~30 aa, would have more potential than peptides of only 15 aa to serve as antigens in diagnostic tests and vaccine developments. The array contained 15aa linear peptides with overlapping sequences 13 aa covering the entire E (393 aa without the transmembrane region) and NS1 proteins of DENV-1 (GenBank AKQ00011), DENV-2 (GenBank AGX15379), DENV-3 (GenBank AFK83760), DENV-4 (GenBank AEW50183), and ZIKV (GenBank AMA12085) isolates. The linear epitopes were mapped with serum samples of dengue (n=19) and Zika (n=28) patients in 16 and 11 arrays, respectively. The serum samples from healthy individuals (n=4) with negative serological tests for dengue and Zika but vaccinated against yellow fever were analyzed in 3 arrays and served as controls.