Análise do efeito adjuvante de nanopartículas de albumina sérica bovina na imunização de camundongos utilizando a proteína não estrutural 1 do Dengue vírus

Abstract

Dengue fever is a viral, systemic disease, considering endemic in more than 128 countries, with about 3.9 billion people worldwide living in infection risk area. Dengue virus is transmitted to humans through the bite of infected female mosquitoes of the genus Aedes. DENV is a RNA virus with positive polarity belonging to the Flaviviridae family, Flavivirus genus. The development of a vaccine conferring immunity, safely and efficiently against all four serotypes of DENV is considered priority. The NS1 is a protein conserved among the serotypes of DENV (1-4) and it is related to the immunopathological process observed in the most severe forms of dengue, including the induction of inflammatory cytokine production and increased endothelial permeability via activation of Toll-like receptors 4. Researches suggest the use of NS1 as a vaccine candidate against dengue fever, since vaccination with recombinant NS1 was able to protect mice against lethal doses of homologous and heterologous serotypes of DENV. Studies in our group have shown that bovine serum albumin nanoparticles (NPBSA) are promising vaccine systems for delivery antigen of DENV and other microbial antigens as likely to have adjuvant activity. This study aimed to verify the adjuvant potential of bovine albumin nanoparticles to induce an immune response in the presence of the NS1 protein of DENV-1. The results indicate that albumin NPs did not show significant cytotoxicity in cultures of macrophagic RAW 264.7 and BHK-21 fibroblast cells, however, the nanoparticles are captured more easily by RAW 264.7 cells than for BHK-21 cells. NS1 of DENV-1 was expressed in prokaryotic system and then used as antigen. Subcutaneous administration of the NPs in mice in the presence or absence of the NS1 protein was able to induce the recruitment of an inflammatory infiltrate at the sites where it was applied. Following immunization, it was observed that NPBSA were able to induce production of anti-NS1 IgM antibodies in 60% of the immunized animals and anti-NS1 IgG in 80%, these data may be related to the adjuvant profile of NP, which when administered associated with NS1, were able to induce a faster class exchange, leading to the production of IgG secreting plasmocytes. Future studies will be carried out to verify if the antibodies produced are able to inhibit the binding of NS1 to TLR-4 receptor and thereby decrease the production of proinflammatory cytokines, responsible for increased vascular permeability and extravasation of plasma.