CHARACTERIZATION OF A VACCINE PLATFORM FOR MUCOSAL ADMINISTRATION BASED ON Lactobacillus AS CARRIER.

URIZA PJ; ROSET MS; G. BRIONES

Congreso; SAIB 2018; 2018

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