Design and development of highly conserved, HLA-promiscuous T cell multiepitope vaccines against human visceral Leishmaniasis

aline silva Barreto ¹ Mariana Nobre Farias Franca ² Tatiana Leão dos Santos dos Reis ³ João Antonio Barbosa Martins Silva ³ Priscila Santos ¹ Fabrícia Alvisi Oliveira ¹ ANGELA MARIA SILVA ¹ Lucas Sousa Magalhães ¹ Danielle Angst Secco ⁴ Maria Aiza Fontes Andrade ⁵ Luís Cristóvão Porto ⁴ Daniela Santoro Rosa ⁶ Rafael Cavalcante ⁵ Cristiane Bani Correa ² John Sidney ⁷ Alessandro Sette ⁷ Roque Pacheco De Almeida ¹ Clarisa B. Palatnik-de-Sousa ^3*

• ¹ Division of Immunology and Molecular Biology Laboratory, Federal University of Sergipe, Aracaju, Brazil
• ² Department of Morphology, Federal University of Sergipe, Sergipe, Brazil, Aracaju, Brazil
• ³ Microbiologia Geral, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
• ⁴ TIXUS Technologic Core for Tissue Repair and Histocompatibility. Rio de Janeiro State University, Rio de Janeiro, Brazil, Rio de Janeiro, Brazil
• ⁵ Department of Pharmacy, Federal University of Sergipe, Lagarto, Sergipe, Brazil, Lagarto, SE, Brazil
• ⁶ Federal University of São Paulo, São Paulo, São Paulo, Brazil
• ⁷ Division of Vaccine Discovery, La Jolla Institute for Immunology (LJI), La Jolla, California, United States

No vaccine is currently licensed against human visceral leishmaniasis (VL), a fatal CD4 + T cell immunosupressive disease against which chemotherapy is reduced to a few toxic drugs. The NH36 nucleoside hydrolase is a DNA metabolism vital enzyme present in all Leishmania species. A vaccine based on such a conserved antigen could protect against both VL and cutaneous leishmaniasis, whose epidemics geographically overlap.Increased frequencies of NH36-specific IL-2 + TNF-α + IFN-γ + -producing CD4 + T cells were associated with VL immune protection. We identified in silico fifteen NH36 conserved epitopes that correspond to promiscuous binders of HLA-DR, -DQ, -DP class II molecules, as well as HLA-A, B and C class I molecules. Collectively, these epitopes provide high worldwide population coverage of both class I and II alleles, and bound to alleles associated with VL susceptibility and resistance. VL asymptomatic individuals showed maximal frequencies of CD4 + and CD8 + multifunctional IL-2 + TNF-α + IFN-γ +producing T lymphocytes in response to these epitopes, with secretion of TNF-α, IL-1β and IL-6. Two recombinant multiepitope vaccines were designed using these epitopes linked by AAA or GPGPG spacers. Both proteins promoted CD4 + and CD8 + T cell responses in PBMC of VL cured and asymptomatic individuals and could be potentially used for universal human vaccination against leishmaniasis.