The Anti-Dengue Virus Peptide DV2 Inhibits Zika Virus Both In Vitro and In Vivo.

The C-terminal portion of the E protein, known as stem, is conserved among flaviviruses and is an important target to peptide-based antiviral strategies. Since the dengue (DENV) and Zika (ZIKV) viruses share sequences in the stem region, in this study we evaluated the cross-inhibition of ZIKV by the stem-based DV2 peptide (419-447), which was previously described to inhibit all DENV serotypes. Thus, the anti-ZIKV effects induced by treatments with the DV2 peptide were tested in both in vitro and in vivo conditions. Molecular modeling approaches have demonstrated that the DV2 peptide interacts with amino acid residues exposed on the surface of pre- and postfusion forms of the ZIKA envelope (E) protein. The peptide did not have any significant cytotoxic effects on eukaryotic cells but efficiently inhibited ZIKV infectivity in cultivated Vero cells. In addition, the DV2 peptide reduced morbidity and mortality in mice subjected to lethal challenges with a ZIKV strain isolated in Brazil. Taken together, the present results support the therapeutic potential of the DV2 peptide against ZIKV infections and open perspectives for the development and clinical testing of anti-flavivirus treatments based on synthetic stem-based peptides.

Diagnostic and vaccine potential of Zika virus envelope protein (E) derivates produced in bacterial and insect cells.

Introduction: In the present study we evaluated the features of different recombinant forms of Zika virus (ZIKV) proteins produced in either bacterial (Eschericha coli) or insect cells (Drosophila melanogaster). The ZIKV-envelope glycoprotein (EZIKV) is responsible for virus entry into host cells, is the main target of neutralizing antibodies and has been used as a target antigen either for serological tests or for the development of subunit vaccines. The EZIKV is composed of three structural and functional domains (EDI, EDII, and EDIII), which share extensive sequence conservation with the corresponding counterparts expressed by other flaviviruses, particularly the different dengue virus (DENV) subtypes. Methods: In this study, we carried out a systematic comparison of the antigenicity and immunogenicity of recombinant EZIKV, EDI/IIZIKV and EDIIIZIKV produced in E. coli BL21 and Drosophila S2 cells. For the antigenicity analysis we collected 88 serum samples from ZIKV-infected participants and 57 serum samples from DENV-infected. For immunogenicity, C57BL/6 mice were immunized with two doses of EZIKV, EDI/IIZIKV and EDIIIZIKV produced in E. coli BL21 and Drosophila S2 cells to evaluate humoral and cellular immune response. In addition, AG129 mice were immunized with EZIKV and then challenge with ZIKV. Results: Testing of samples collected from ZIKV-infected and DENV-infected participants demonstrated that the EZIKV and EDIIIZIKV produced in BL21 cells presented better sensitivity and specificity compared to proteins produced in S2 cells. In vivo analyses were carried out with C57BL/6 mice and the results indicated that, despite similar immunogenicity, antigens produced in S2 cells, particularly EZIKV and EDIIIZIKV, induced higher ZIKV-neutralizing antibody levels in vaccinated mice. In addition, immunization with EZIKV expressed in S2 cells delayed the onset of symptoms and increased survival rates in immunocompromised mice. All recombinant antigens, either produced in bacteria or insect cells, induced antigen-specific CD4+ and CD8+ T cell responses. Conclusion: In conclusion, the present study highlights the differences in antigenicity and immunogenicity of recombinant ZIKV antigens produced in two heterologous protein expression systems.