Evaluation of the immunopotentiating effect of the molecular adjuvant RS09 in a peptide vaccine formulation against sporotrichosis

Abstract

Sporotrichosis is a subcutaneous fungal infection of subacute or chronic evolution, caused by pathogenic species of the genus Sporothrix. It has a cosmopolitan geographic distribution and is considered an endemic zoonosis in Brazil, transmitted by cats infected by S. brasiliensis, the most pathogenic species among the Sporothrix genus. Cases of sporotrichosis were only reported in the State of Rio de Janeiro, but today the disease is considered a public health problem, is frequently reported in the 26 states of Brazil. Faced with this problem, prophylactic and/or therapeutic vaccination for cats has been proposed as a promising alternative to reducing the zoonotic transmission of the disease. Previous studies showed that a mixture of Sporothrix spp enolase peptides formulated with Freund's adjuvant, induced a protective immune response in BALB/c mice challenged with S. brasiliensis. Although an encouraging result, the immune response profile (Th1/Th2 and Th17) induced by the peptide formulation was evidently stimulated by Freund's adjuvant, considered toxic for veterinary and human use. The RS09 peptide, a synthetic agonist of the TLR-4 receptor, has been shown to contribute to the induction of Th1/Th17 immune response when formulated or fused with different recombinant and peptide antigens. Based on this property and taking into account the prohibition of Freund's adjuvant for clinical use, we propose to evaluate the potentiating effect of the RS09 peptide fused to the 2765 peptide of enolase, which proved to be antigenic and immunogenic among the chosen peptide mixture of the enolase protein. We believe that the results derived from the project will be able to validate the use of RS09 adjuvant in peptide formulations against sporotrichosis.(AU)