1). At each time point, tumour size was determined by measuring the smallest diameter (a) and the biggest diameter (b) by calliper. Tumour volume was calculated using the formula: V = (a2b)/2 . Measurement of antibody responses. Pooled sera were prepared after retro-orbital bleeding from the whole blood samples of each group 3 weeks after the booster injection (prechallenge),
and twice post-challenge (2 and 4 weeks after challenge, Fig. 1). The pooled sera of each group were stored at −20 °C. E7-specific IgG1 buy Y-27632 and IgG2a in the sera were measured by enzyme-linked immunosorbent assay (ELISA). Briefly, a 96-well flat-bottom ELISA plate (NUNC) was coated overnight at 4 °C with 100 μl of 5 μg/ml rE7 protein diluted in PBS (pH 7.2). Then, the plate was rinsed
with washing buffer (0.5% (v/v) Tween-20 in PBS), incubated with blocking buffer (1% BSA in PBS) for 2 h at 37 °C. The pooled sera were serially diluted from 1:250 to 1:2000 in dilution buffer (0.5% (v/v) Tween-20 in blocking buffer), added to the plate and incubated for 2 h at 37 °C. After rinsing with washing buffer, the plate was incubated with biotin-conjugated rat anti-mouse IgG1 (Cedarlane Laboratories, Hornby, ON, Canada) or biotin-conjugated goat anti-mouse IgG2a (Southern biotechnology Association. Inc, Birmingham, AL, USA) for find more 2 h at 37 °C. Then, the plates were washed and incubated with streptavidin-horseradish peroxidase diluted in PBS (1:500; Sigma) for 1 h. Hundred microliters of O-Phenylenediamine (Sigma) in citrate phosphate buffer (citric acid 0.1 m, Na2HPO4 0.2 m, pH 4.5) was added as the substrate, followed by incubation for 30 min at 37 °C. The reaction was stopped with 1 m H2SO4. The ELISA plate was read at 492 nm. Cytokine assay. Three weeks after booster, Acyl CoA dehydrogenase two mice from each group were killed and
the spleens were removed (Fig. 1). An amount of 2 × 106 cells/ml of red blood cell-depleted pooled splenocytes from immunized mice of each group were resuspended in complete RPMI medium 1640 supplemented with 5% FCS, 2 mm glutamine, 5 × 10−5 mm mercaptoethanol (2-ME), 10 mm HEPES and 40 μg/ml gentamycin. Cells were incubated in U-bottomed, 96-well plates (Costar, Cambridge, MA, USA) in the presence of 20 μg/ml of rE7 protein, 20 μg/ml of rNT-gp96 protein, RPMI 5% as negative control and 5 μg/ml of concanavalin A (ConA) as positive control. Cells were cultured for 3 days at 37 °C and 5% CO2. Supernatants were then collected and frozen at −70 °C, until the samples were analysed. The presence of interferon-γ (IFN-γ) and interleukin-5 (IL-5) was measured using a DuoSet ELISA system (R&D Systems, Minneapolis, MN, USA) according to the manufacturer’s instructions. All data were represented as mean ± SD of duplicate for each set of samples.