AN EXPERIMENTAL VACCINE FOR HEPATITIS E ADJUVANTATED WITH SAPONINS DERIVED FROM LEAVES FROM THE SOAP TREE QUILLAJA BRASILIENSIS

MULLER, MELISA FLORENCIA; WALLACE, FEDERICO ; SACUR, JACINTO ALFREDO; VERA, MARÍA DANIELA; MATIAS BRANCHER, JULIA RAFAELA; VILLENA, JULIO; KITAZAWA, HARUKI; FERREIRA, FERNANDO; OLIVARO, CRISTINA; VIZOSO PINTO, MARÍA GUADALUPE

Londres

Simposio; 2nd International Hepatitis E Symposium; 2023

● Background and aimsHepatitis E is increasingly reported in industrialized countries mainly associated to zoonotictransmission via consumption of meat products derived from contaminated animals. HepatitisE virus genotype 3 (HEV-3) is the main genotype associated with this transmission. Althoughswine, the main reservoir, do not suffer from the disease, a veterinary vaccine could helpcontrolling the disease before it reaches human beings. QuilA® is a potent adjuvant used inveterinary vaccines and consists of a mixture of saponins obtained from the barks of theChilean tree Quillaja Saponaria. The high demand for the pharmaceutical and cosmeticindustries and the tree destructive source have posed the trees at risk. We have recentlyobtained saponins extracts from the leaves and bark of Quillaja brasilensis (an endemic treefrom Argentina, Uruguay, Brazil, and Paraguay) and isolated a novel molecule, Qb1, withadjuvant potential. The aim of this study was to evaluate an experimental vaccine consisting ofthe recombinant protein HEV-3 ORF2 mixed with the extracts and purified saponins of Quillajabrasiliensis.● MethodsFraction B from leaves or cortex were obtained by fractionation of an aqueous extract on a C18SPE column. Fraction B3 was further purified by semi-preparative-HPLC on a reverse phasecolumn, affording a novel triterpenic saponin named Qb1. We evaluated if saponin mixturescould activate macrophages in vitro. We determined the production of cytokines involved inthe generation of adaptative immunity and regulators of innate immunity pathways (TNF-α, IL-17, IL-6, IL-1α, IL-1β, INF-γ, IL-4, IL-10, TGF-β, IL-27, A20, Bcl-3, SIGIRR, IRAK-M, MKP-1 andTollip) by qPCR in porcine macrophages (3D4/31) stimulated with 1,6 ug/ml saponin solutions.Then, we administered the recombinant capsid protein ORF2 (20 ug per dose) produced in E.coli mixed with saponins (20 to 50 ug) to BALB/c mice: 1)Fraction B cortex + ORF2; 2)Fraction Bleaves + ORF2; 3)Qb1 + ORF2; 4)ORF2 (control withoutadjuvant) and 5)QuilA®QuilA + ORF2.Mice received 2 doses every 4 weeks subcutaneously; blood samples were taken every 2weeks to follow up specific antibodies by ELISA.● ResultsAll saponins significantly (p