Predição de uma vacina multi-epítopo contra o vírus da febre amarela através de ferramentas de imunoinformática e modelagem molecular

Abstract

Outbreaks of Yellow Fever are observed periodically, especially in endemic regions. However, in 2016, two related outbreaks of urban yellow fever (Luanda/Angola and Kinshasa/Democratic Republic of Congo) exported cases to other countries, including China, demonstrating that Yellow Fever represents a serious global threat that requires new strategic planning. This fact has generated concern about the control of this arbovirus, mainly because there is no specific treatment for this disease. The attenuated virus vaccine has been the most effective form of prevention, but its use is not recommended for specific groups of individuals because of potential adverse effects. In this perspective, a prototype of a multi-epitope subunit vaccine capable of generating an effective immune response against different strains of Yellow Fever virus was the object of this research. To develop this prototype, initially, the whole viral proteome - composed of three structural proteins (E, prM and C) and seven non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5) - of 234 strains were used for the prediction of B and T cell epitopes through Immunoinformatics and Molecular Modeling tools. After an evaluation of the number of alleles of the human leukocyte antigen (HLA) system that these epitopes had affinity for and tests for antigenicity, immunogenicity, allergenicity, toxicity and conservation, 10 lymphocyte T cytotoxic (TCL) and 5 helper T lymphocyte (THL) epitopes were found with overlapping B lymphocyte (LB) epitopes. These epitopes were linked to each other and to a β-defensin adjuvant, giving rise to a primary amino acid sequence with suitable physicochemical properties and theoretical vaccine potential, specifically high immunogenicity and high population coverage. The 3D structure of this sequence was designed, refined and its quality validated. Then, anchoring of the vaccine prototype to the Toll-like receptor (TLR-2) was performed to assess its binding capacity and affinity, this affinity of the vaccine-receptor complex was equated in a QM:MM optimized model and the key intermolecular interactions identified. Furthermore, the vaccine model simulated a good immune response and presented an optimized codon sequence that could be incorporated into the pET-28a(+) vector after in silico cloning test. In summary, the designed multi-epitope vaccine prototype is potentially effective as a tool for Yellow Fever prevention and control, however the computational predictions need to be validated by preclinical studies.