Homologous prime-boost strategy with TgPI-1 improves the immuneresponse and protects highly susceptible mice against chronicToxoplasma gondii infection

VANESA R. SÁNCHEZ, IGNACIO M. FENOY, MARIANO S. PICCHIO, ARIADNA S. SOTO, NADIA ARCON,ALEJANDRA GOLDMAN, VALENTINA MARTIN

ACTA TROPICA

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015

0001-706X

Subunit-based vaccines are safer than live or attenuated pathogen vaccines, although they are generallyweak immunogens. Thus, proper combination of immunization strategies and adjuvants are needed toincrease their efficacy. We have previously protected C3H/HeN mice from Toxoplasma gondii infection byimmunization with the serine protease inhibitor-1 (TgPI-1) in combination with alum. In this work, weexplore an original vaccination protocol that combines administration of recombinant TgPI-1 by intra-dermal and intranasal routes in order to enhance protection in the highly susceptible C57BL/6 strain.Mice primed intradermally with rTgPI-1 plus alum and boosted intranasally with rTgPI-1 plus CpG-ODNelicited a strong specific Th1/Th2 humoral response, along with a mucosal immune response character-ized by specific-IgA in intestinal lavages. A positive cellular response of mesentheric lymph node cells andTh1/Th2 cytokine secretion in the ileon were also detected. When immunized mice were challenged withthe cystogenic Me49 T. gondii strain, they displayed up to 62% reduction in brain parasite burden. More-over, adoptive transfer of mesenteric lymph node cells from vaccinated to naïve mice induced significantprotection against infection. These results demonstrate that this strategy that combines the administra-tion of TgPI-1 by two different routes, intradermal priming and intranasal boost, improves protectiveimmunity against T. gondii chronic infection in highly susceptible mice.