The experimentally infected mice (which inoculated with blood of naturally infected camels with Trypanosoma) were sacrified at high parasiteamia and the blood was collected in tubes with anticoagulant. The collected blood was centrifuged at 3000 r.p.m. for 15 minutes. The plasma was removed and several washing using phosphate buffer solution pH. 7.2 were accomplished. The erythrocytes were lysed by using distal water. The suspension was centrifuged at 3000 rpm for 15 minutes and washed several times with distal water. The supernatant was discarded and the sediment was kept in ice bag. The sediment was sonicated with ultrasonicator in ice bag for 3 minutes with 30 second interval then centrifuge for 45 minutes at 4 ºC at 14000 r.p.m. The supernatant was used as antigen and stored frozen until used. The concentration of protein in the antigen was determined by the method described by Lowry et al., (1951).