INDUCTION OF NEUTRALIZING ANTIBODY IN MICE BY IMMUNIZATION WITH RECOMBINANT 56 KDA PROTEIN OF ORIENTIA-TSUTSUGAMUSHI

Anti-oriental antibody inhibits Orientia tsutsugamushi attachment to, and penetration of, host cells. However, O. tsutsugamushi antigens tha t induce the production of a neutralizing antibody have not been ident ified. The authors immunized mice and rabbits with the recombinant 56 kDa protein of O. tsutsugamushi fused to the maltose binding protein o f Escherichia coli (MBP-Bor56) and analysed their effect on O. tsutsug amushi attachment to or penetration of L929 cells. O. tsutsugamushi at tachment and penetration were measured by using an indirect immunofluo rescent antibody assay (IFA). O. tsutsugamushi growth in L929 cells wa s determined by [H-3]thymidine uptake assay. By IFA, we observed a 96% reduction of attachment or penetration of O. tsutsugamushi treated wi th rabbit anti-MBP-Bor56 sera. [H-3]thymidine uptake showed that mouse anti-MBP-Bor56 sera caused a 91% reduction in O. tsutsugamushi growth , when compared to mouse anti-MBP sera. These results suggest that the 56 kDa protein of O. tsutsugamushi plays an important role in O. tsut sugamushi attachment to or penetration of cells. (C) 1997 Elsevier Sci ence Ltd.