Characterization of a vaccine platform for mucosal administration based on Lactobacillus as carrier

MARA ROSET; GABRIEL BRIONES; PAULA URIZA

Congreso; 54th Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2018

Since mucosal surfaces are the main route of entry for microbial pathogens, the induction of a protective immunity at this level emerges as an attractive field of study for vaccine development. It has been reported that oral route is capable to induce an immune response at level of other distal mucosal surfaces and eventually at systemic level. Different strategies have been postulated for antigen delivery to gut mucosal surface, here we have proposed to use a probiotic bacteria Lactobacillus acidophilus (LB) as a vaccine carrier for targeting antigens into gut mucosa. We selected Escherichia coli O157:H7 (STEC) as a experimental model. STEC is an emerging bacterial pathogen that has a great regional impact, responsible for the Hemolytic Uremic Syndrome. As antigen, three STEC proteins (EspA, Intimin, Tir) were fused-in-frame and combined also with the binding domain of the S-layer protein (SLAP domain) of LB (EITS). EITS binding to the lactobacilli surface was estimated by Quantitative Infrared Western Blots, determining that until 20 µg of EITS protein can be coated on 108 lactobacillus. BALB/c mice were orally immunized with EITS-coated lactobacilli (0, 2 and 4 weeks). Although no significant increase of fecal IgA titers against EIT was detected, mice EITS-immunized were able to control an oral challenging infection (1010 UFC of STEC) estimated by reduction of fecal shedding of STEC.