All animal procedures and experimental protocols were in accordance AZD6244 with the local Ethical Committee for Animal Research (CEEA – Protocol no. 212). NOD mice were distributed in three groups: non-immunized NOD mice (NOD); NOD mice immunized with BCG vaccine (BCG–NOD) and NOD

mice immunized with the prime-boost BCG/pVAXhsp65 (BCG/DNAhps65–NOD). Diabetes type 1 in male C57BL/6 mice was induced with STZ and animals were allocated into four groups: non-immunized, non-diabetic mice (control); non-immunized diabetic mice (STZ), mice immunized with BCG (BCG-STZ) and mice immunized with the prime-boost BCG/pVAX-hsp65 (BCG/DNAhps65–STZ). The vaccine pVAXhsp65 was derived from the pVAX vector (Invitrogen, selleck Carlsbad, CA, USA), digested previously with BamHI and NotI (Gibco BRL, Gaithersburg, MD, USA) by inserting a 3·3 kb fragment corresponding to the Mycobacterium leprae hsp65 gene

and the cytomegalovirus (CMV) intron A. DH5a Escherichia coli transformed with plasmid pVAX or the plasmid carrying the hsp65 gene (pVAXhsp65) were cultured in Luria-Bertani liquid medium (Gibco BRL) containing kanamycin (100 μg/ml). The plasmids were purified using the Concert High Purity Maxiprep System (Gibco BRL). Plasmid concentrations were determined by spectrophotometry at 260 and 280 nm by using the Gene Quant II apparatus (Pharmacia Biotech, Amersham, UK). BCG vaccine [50 μl containing around 105 colony-forming units (CFU)] was administered subcutaneously at the base of the tail when NOD mice were 7 weeks old and C57BL/6 mice were 4–6 weeks old. In the prime-boost group, animals were additionally injected with pVAXhsp65 (100 μg/100 μl) associated with 25% of saccharose by the intramuscular route (quadriceps muscle) 15 days after BCG immunization. NOD mice were monitored until their 29th week of life, whereas STZ groups were monitored for 21 days after diabetes induction. Body weight and blood glucose level were measured weekly and insulitis scores were measured only after euthanasia.

In addition, in the NOD mice, Ergoloid cytokine production by spleen cells and the presence of Treg cells in the spleen were analysed. In order to induce diabetes, male C57BL/6 mice were given intraperitoneal injections of STZ diluted in citrate buffer (40 mg/kg; Sigma-Aldrich, St Louis, MO, USA) for 5 consecutive days. Using this protocol, glycaemia was determined once before the first STZ dose and three times after the last dose. Non-fasted glucose concentration was determined in blood samples collected from the facial vein and measured using Prestige LX Smart System Test-strips (Home Diagnostic, Inc., Fort Lauderdale, FL, USA). NOD mice are known to develop hyperglycaemia around week 12 and, therefore, blood glucose concentration was measured from the 11th week onwards. Animals were considered diabetic when blood glucose levels were higher than 200 mg/dl during 2 consecutive weeks.