BABESIA RODHAINI AND BABESIA-MICROTI - CROSS-IMMUNITY AND CROSS-ANTIGENS

Cross reactivity of Babesia rodhaini (B. rodhaini) and Babesia microti (B. microti) antigens against Babesia-chronically infected mice sera was examined using indirect fluorescent antibody (IFA) technique and w esternblotting. The effect of monoclonal antibody #7 (mAb #7), which r ecognized both B. microti and B. rodhaini antigens, was also studied a gainst Babesia-infections. Passive immunization with mAb #7 was carrie d out to clarify the relationship between cross-reactive antigens and progression of Babesia infection. Results of IFA assay showed cross re activity in B. microti and B. rodhaini antisera at a dilutions of 1:51 2 and 1:128, respectively. Each type of antiserum exhibited parasite s pecific fluorescence. Immunoblotting demonstrated the reactivity of B. microti and B. rodhaini antisera with the 70 and 32 kilodaltons (kDa) B. rodhaini antigens, and with the 70 kDa B. microti antigen, respect ively. These results suggest a stronger cross reactivity of B. microti antiserum compared to B. rodhaini antiserum. Monoclonal antibody #7 r eacted with 70 and 30 kDa antigens of B. microti, and with 70 and 32 k Da antigens of B. rodhaini. Passive immunization using mAb #7 showed a delayed development in high levels of parasitemia in both Babesia spp ., compared to the control groups. These results demonstrate the appar ent role of mAb #7 in suppressing the onset of parasitemia.