Evaluation of cross-reactivity induced after immunization of mice with mutated or non-mutated envelope proteins of dengue and zika viruses.

• Grant number: 23/02433-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2023
• End date: May 31, 2024
• Field of knowledge: Biological Sciences - Immunology - Cellular Immunology
• Principal Investigator: Silvia Beatriz Boscardin
• Grantee: Vitoria Maria Pereira da Silva
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The genus Flavivirus is composed of single-stranded positive-sense RNA genome viruses, comprising different viruses, such as dengue virus serotype 2 (DENV-2) and ZIKA virus (ZIKV), both of great importance in public health in Brazil. Flaviviruses are structurally similar, and this similarity is responsible for the induction of cross-reacting antibodies, which mainly target the envelope (E) protein. More specifically, cross-reacting antibodies appear to be directed to the fusion loop (FL) portion of the E protein, a highly conserved region among flaviviruses linked to the fusion of viral and host cell membrane. The occurrence of cross-reactivity has been related to an increase in infection, as well as being an obstacle to correct detection in serological tests and to the development of safe and effective vaccines and therapies.In an effort to mitigate this occurrence, it has been reported that specific mutations in FL appear to reduce cross-reactivity. To study in more detail this phenomenon, this project aims to evaluate the cross-reactivity induced after immunization with E proteins mutated and unmutated (wild-type) in the fusion loop of dengue virus serotype 2 (DENV-2) and ZIKA virus (ZIKV). DENV-2 and ZIKV E proteins, mutated in the fusion loop and wild-type, will be produced in Drosophila S2 cells and subsequently purified. C57BL/6 mice will be immunized with the produced proteins in a vaccine scheme of 2 to 3 doses, 14 days apart. At the end of the planned administration, the animals will undergo a bleeding procedure to collect blood and obtain serum. Finally, two enzyme-linked immunosorbent assays (ELISA) will be performed to titrate the antibodies produced by the animals and analyze the cross-reactivity of the same antibodies using the previously produced E proteins.