Desenvolvimento de antiveneno piloto contra os venenos de serpentes Bothrops ayerbei, Bothrops rhombeatus, Bothrops asper e Lachesis acrochorda, usando nanopartículas de quitosana como imuno adjuvante

Abstract

Snake bite poisoning is a neglected tropical disease, and one of the main factors aggravating this problem is the scarcity of effective antivenoms in sufficient quantities to treat victims. In such circumstances, it is essential to research new strategies for the production and improvement of snake antivenoms, using substances capable of stimulating the immune response, as has been repeatedly reported for chitosan. Thus, the objective of this research was to develop a prototype antivenom against the venoms of Lachesis acrochorda (SVLa), Bothrops ayerbei (SVBay), Bothrops rhombeatus (SVBr), and Bothrops asper (SVBas), using chitosan nanoparticles (NPs) as immunoadjuvants. The nanoparticles were obtained by ionic gelation, loaded with viper venoms (SVLa, SVBay, SVBr, and SVBas), and characterized in terms of their physical-chemical properties and loading efficiency. Next, a process of immunization in rabbits was carried out, followed by immunorecognition tests. The NPs exhibited an encapsulation efficiency of 77.5%, an average size of 85.1 nm, a zeta potential of approximately +7.4 mV, and a polydispersity index ≤ 0.5, indicating NPs with stable physicochemical characteristics. Furthermore, antibodies produced by rabbits immunized with chitosan NPs loaded with venoms demonstrated a protein recognition immune response equal to or greater than that observed in control rabbits and commercial antivenoms tested, both in Western blot and ELISA assays, indicating greater antigenic recognition capacity compared to conventional antivenoms. Regarding in vivo neutralization tests, a good response was observed, inhibiting deaths equally or more than the control rabbit antivenom without nanoparticles. The immunization model in rabbits demonstrated greater efficacy of chitosan NPs with poisons (SVLa, SVBay, SVBr, and SVBas) compared to conventional immunoadjuvants, such as aluminum hydroxide and Freund's adjuvant. Thus, chitosan nanoparticles loaded with venoms represent a promising biotechnological approach for the development of antivenom immunotherapies.