Biochemical Basis of Virulence in Epidemic Typhus
Annual progress rept.
UNIVERSITY OF SOUTH ALABAMA MOBILE DEPT OF MICROBIOLOGY AND IMMUNOLOGY
Pagination or Media Count:
Rickettsia prowazeki were assessed for their in vitro susceptibility to phagocytosis by rabbit polymorphonuclear leukocytes PMN. ATP labeling was used to quantitatively determine phagocytosis and adsorption. Rickettsiae were less susceptible to phagocytosis then were Escherichia coli and Neisseria gonorrhoeae. Although rickettsiae were similar to E. coli in susceptibility to superoxide and activated halide, few phagocytized rickettsiae were inactivated 45 min after being ingested by PMN and some rickettsiae were observed free in the PMN cytoplasm. At low rickettsia PMN multiplicities, phagocytosis increased as a linear function of time, but at high multiplicities MOI50 rickettsiae were phagocytized during only the first 10 min of incubation. PMN were damaged in the presence of high rickettsial multiplicities such that they released lactate dehydrogenase into the medium and lost the ability to phagocytize both rickettsiae and E. coli. This rickettsial leukotoxic activity was associated with phospholipase activity which was similar to the phospholipase activity associated with rickettsial hemolysis, and the amount of leukotoxic activity in a given rickettsial sample correlated with the relative hemolytic activity of that sample.
- Medicine and Medical Research