CENTRO DE INVESTIGACION Y DESARROLLO EN INMUNOLOGIA Y ENFERMEDADES INFECCIOSAS
Unidad Ejecutora - UE
congresos y reuniones científicas
NOVEL ORAL VACCINE BASED ON THE FULL REPERTOIRE OF GIARDIA VSPs PREVENTS ESTABLISHMENT OF INFECTION AND REDUCES CHRONIC GIARDIASIS IN DOMESTIC ANIMALS
SERRADELL, MARIANELA; SAURA, ALICIA; RUPIL, LUCÍA; GARGANTINI, PABLO; FAYA, MARCELA; FURLAN, PAULINA; LUJÁN, HUGO
Congreso; XXVII Reunión Anual - SAP; 2015
Sociedad Argentina de Protozoología
Giardia lamblia is an intestinal parasite of humans and one of the most common enteric parasites of domestic animals, including cats, dogs, and cattle. Clinical manifestations of giardiasis, such as acute or chronic diarrhea, anorexia, weight loss and lethargy, have been associated with Giardia infections in both domestic and farm animals. A few anti-parasitic drugs are used to treat giardiasis, but re-infections are common and drug resistant strains have already been reported. Unfortunately, efficient vaccines against Giardia are not available. Giardia undergoes antigenic variation, a mechanism that allows parasites to evade the host?s immune response. Antigenic variation is characterized by the continuous switching in expression of a family of homologous genes encoding surface antigens. Recently, we found that the mechanism controlling variant-specific surface proteins (VSPs) switching in Giardia involves components of the RNA interference (RNAi) pathway. Only one VSP, from a repertoire of ~200 VSP genes, is expressed on the surface of individual trophozoites, but disruption of the RNAi machinery generates trophozoites expressing the entire repertoire of VSPs. We previously demonstrated that oral immunization of gerbils with VSPs isolated from these altered parasites shows high levels of protection, clearly indicating that targeting the entire repertoire of surface antigenic variants is an effective approach to prevent infections. In this work, we tested this vaccine in cats and dogs, demonstrating that it is highly efficient in preventing new infections and in alleviating chronic giardiasis in both experimentally and naturally acquired animal infections. Remarkably, vaccination of dogs in a hyperendemic shanty town decreased the level of Giardia infections in children living in the community, clearly indicating that vaccination of domestic animals also prevents the zoonotic transmission of the parasite to humans.