Abstract
Mice were infected with a non-lethal strain of Babesia microti and challenged with a lethal strain of B. microti, 1 week, 2 weeks, 3 weeks, 4 weeks, and 8 weeks post-infection. At all times tested the mice were protected from lethal challenge if they were first exposed to the non-lethal strain of parasite. Passive transfer of immune sera from non-lethal strain infected mice, to naive mice then infected with the lethal strain, showed no protective effects. Immune sera reacted positively with the homologous antigen in both the IFA test and Western Blotting analysis but not with the antigen of the heterologous strain. Polyacrylamide gel electrophoresis showed multiple differences between the proteins of the lethal and non-lethal strains of parasite. The effects of two specific and two nonspecific immunostimulants were tested on these two strains of B. microti. Avridine and killed Corynebacterium parvum showed pronounced effects ranging from suppression to enhancement of parasitemia, depending on the time of administration as well as the strain studied. However, MDP and IL 2, stimulants with more defined and specific effects on the immune system, failed to affect parasitemias of the strains tested. The protection afforded by the non-lethal strain to the lethal strain of B. microti does not seem to be antibody mediated as the antibodies produced against the two strains do not cross-react. However, as evidenced by the effects of non-specific immunostimulants on the infections and their proposed mechanisms of action, cell mediated immunity, possibly involving macrophages, NK cells and gamma interferon, could provide the protective effects seen in this study.
Sharp, Susan Elaine (1985). Studies of cross-strain protection between two strains of Babesia microti and the effects of several immunomodulators on these two strains. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -597411.