The mice were housed in autoclaved micro isolator cages (Alesco, Brazil) and manipulated under aseptic conditions. All procedures were performed in accordance with the Brazilian Committee for Animal Care and Use (COBEA) guidelines. The presence of the HLA-class II transgene in all mice studied was verified by molecular biology techniques

using skin biopsies. All mice that did not have the HLA class II transgene were discarded and were not used in this study. We also evaluated the presence of the HLA class II molecules on the surface of antigen presenting cells from the peripheral blood to control for the expression of the specific transgene (data not shown). HLA-class II transgenic mice received two subcutaneous doses (100 μL) on days 0 and 14 of a suspension containing 50 μg of StreptInCor absorbed find more onto 300 μg of Al(OH)3 (aluminum hydroxide). Animals receiving saline plus adjuvant were used as

experimental controls for immunization. Sera samples were obtained Gemcitabine supplier from mice on day 28 following immunization while under light anesthesia by retro-orbital puncture. Sera antibody titers were determined by ELISA. Briefly, 1 μg of StreptInCor vaccine epitope and overlapping peptides, porcine cardiac myosin (Sigma, USA), or M1 recombinant protein (clone kindly provided by Prof Patrick Cleary, University of Minnesota Medical School, MN, USA) produced and purified in our lab, were diluted in coating buffer (0.05 M carbonate–bicarbonate,

pH 9.6, 50 μL/w) and was added to a 96-well MaxiSorp assay plate (Nunc, Denmark). After overnight incubation, the unless plates were blocked with 0.25% gelatin (Sigma) diluted in 0.05% Tween-20 (Sigma, USA) in PBS (dilution buffer) for 1 h at room temperature. Starting at 1/100 in dilution buffer, serial 2-fold dilutions were added to the plates (50 μL/w). After a 2 h incubation at 37 °C and three washes (200 μL/w) with 0.05% Tween 20 in PBS (rinse buffer), the plates were incubated for another hour at 37 °C with peroxidase-conjugated anti-mouse IgG (Pharmingen, USA) at 1:2000 in dilution buffer (50 μL/w). The plates were then washed three times (200 μL/w) with rinse buffer, and the reaction was revealed with 50 μL/w of 0.4 mg/mL ortophenylenediamine (OPD, Sigma, USA) in 100 mM sodium citrate (Merck, Germany) containing 0.03% H2O2 (Merck). After 10 min at room temperature, the reactions were stopped using 4 N H2SO4, and the optical density was evaluated using a 490 nm ELISA filter in an MR4000 ELISA plate reader (Dynatech, USA). To study IgG isotypes, the biotinylated conjugates anti-mouse IgG1, IgG2a, IgG2b and IgG3 (Pharmingen, USA) were used at 2 μg/mL (50 μL/w) and incubated for 1 h at 37 °C.