Evaluation of the immunomodulatory properties of type II heat-labile toxins produced by enterotoxigenic Escherichia coli (ETEC) administered by transcutaneous route.

Author(s)

Camila Mathias dos Santos

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2009-05-27

Examining board members

Luis Carlos de Souza Ferreira; Paulo Lee Ho; Roxane Maria Fontes Piazza

• Advisor: Luis Carlos de Souza Ferreira

Abstract

Heat-labile toxins expressed by enterotoxigenic Escherichia coli (LT-I, LT-IIa and LT-IIb) are potent systemic and mucosal adjuvants. These proteins have low identity (<14%) in their B subunits and bind to different receptors, which may result in differential biological properties. The objective of this work was to evaluate the immune response induced by LT-IIa toxin and its pentameric B subunit (LT-IIaB) delivered by transcutaneous and intradermic routes. Initially the proteins of interest were expressed in recombinant E. coli strains, purified and tested for functionality in vitro. In a second moment, the immunomodulatory properties of LT-IIa and LT-IIaB, immunogenicity and adjuvant activity, were evaluated in mouse model. The humoral and cellular immune responses induced against ovalbumin (OVA) used as antigen were determined. The results show that the adjuvant activity of LT-IIa and its B pentamer depends on the route of inoculation and that LT-I and LT-IIa differ both on induction of inflammation and activation of immune responses in mice. (AU)