cruzi challenges [20-22]. In the present study, we investigated whether the immune response against TcSP, a member of the TS superfamily, or the A, R or C domains of TcSP is capable of inducing protection against both acute and chronic T. cruzi infection in mice. Trichostatin A Because differential immune responses have been reported when immunity was induced by DNA or recombinant proteins [23, 24], animals were immunized with DNA encoding for either TcSP, the A, R or C domains or with the corresponding recombinant proteins to compare the immune response induced by the two antigen delivery systems. The immune response was evaluated with regard to the antibody response, cytokine production

and the capacity of the antigen to confer protective immunity against T. cruzi infection in a mouse model. We found that immunization with DNA that encoded the R domain of TcSP induced protection in mice against challenge with T. cruzi. Female BALB/c mice, 4–6 weeks old, were used in all of the experiments, and both immunized and unimmunized mice had access to food and water ad libitum. The H8 strain of T. cruzi was a kind gift from Dr. Jorge E. Zavala Castro, Centro de Investigaciones Regionales ‘Dr. Hideyo Noguchi’,

Universidad Autónoma de Yucatán, Mérida, Yucatán, México. T. cruzi was maintained and propagated by serial passage in naive mice. The mice were housed in a controlled environment and managed according to the National Institutes of Health Guide for Care and Use of Experimental Animals, with the approval of the CINVESTAV-IPN Animal Care and Use Committee. The DNA encoding the surface protein (SP) of T. cruzi (TcSP) was obtained from the genomic clone Vincristine in vivo A83 (GenBankTM database accession number HQ642765, ORF1) by digesting the plasmid pBSKA83 with EcoR I and subcloning in frame into the eukaryotic expression vector pBluescript-CMV

(Stratagene), thus obtaining the plasmid pBKTcSP. The DNA fragments coding for the TcSP domains A (N-terminal, 459 aa), R (central amino acid repeats sequence, 5 aa repeats (PKPAE)48) Thalidomide or C (C-terminal, 110 aa) were amplified by PCR with the following primers: SPAF 5′-GGGAATTCATTGGCTTCCTCACCGATGC-3′, SPAR 5′-GATCTCCTTCATCTTCTGCAGCGGAGGTGGAATGGTGACTT-3′; SPRF 5′-GGGAATTCAAAGTCACCATTCCACCTCC-3′, SPRR 5′-GATCTCCTTCATCTTCTGCAGTGAGGATGTCGCGGCATTGG-3′; SPCF 5′-GGGAATTCAATGCCGCGACATCCTCAGC-3′, SPCR 5′-GATCTCCTTCATCTTCTGCAGAAGGCTGCTGCTGAGTGTCG-3′. The PCR contained 1 μg of the pBSKA83 template, 2 mm MgSO2, 0·4 mm of each dNTP, 1X PCR buffer and 2.5 U of Taq DNA polymerase. PCR conditions involved denaturizing at 94°C for 30 s, primer annealing at 70°C for 30 s, extension at 72°C for 30 s for 30 cycles and a final extension at 72°C for 10 min. The amplified DNA products TcSPA (1367pb), TcSPR (758pb) and TcSPC (317pb) were digested with EcoR I and Pst I and cloned in frame into the pBluescript-CMV and pRSETB (Invitrogen, Carlsbad, CA, USA) expression vectors.