ABSTRACT
The features of intracellular development of the virulent Breinl strain and 3 vaccine E strains of Rickettsia prowazeki have been followed in continuous FL, McCoy, and B cell cultures at temperatures of 30, 35, 37, 38.5 and 40 degrees C. The virulent Breinl strain multiplied well at these temperatures in McCoy and B cells but in had been gradually lost when cultured at 40 degrees C in FL cells. In contrast to the virulent Breinl strain the vaccine E strains have lost their capacity of long term reproduction at 38.5 degrees C. At 40 degrees C the E strains did not multiply in and had been eliminated from the McCoy and B cells; thus the vaccine E strains revealed a ts-phenotype and, accordingly, it was found to represent a ts-mutant.
Subject(s)
Rickettsia prowazekii/growth & development , Rickettsial Vaccines/analysis , Vaccines/analysis , Animals , Cell Line , Chick Embryo , Rickettsia prowazekii/immunology , Rickettsia prowazekii/pathogenicity , Temperature , Time FactorsABSTRACT
Vaccine and virulent strains of Rickettsia prowazeki differ by the degree of reproduction in McCoy, B, and chick embryo cells but replicate to similar levels in FL cells. As distinct from the virulent Breinl strain, the vaccine E strain rickettsiae permanently lost their capacity for long-term reproduction in McCoy cell cultures but retained their capacity to adsorb on to and penetrate into these cells. Consequently, the reproduction of rickettsiae is limited at later stages of intracellular infection. The E strain of R. prowazeki has been defined as a conditional lethal, host-dependent (hr) mutant.
Subject(s)
Cells, Cultured/microbiology , Rickettsia prowazekii/growth & development , Amnion , Animals , Cell Line , Chick Embryo , Humans , Mice , Rickettsia prowazekii/pathogenicity , Rickettsial Vaccines , Species Specificity , Synovial MembraneABSTRACT
Microcinematography, cytological and cytochemical studies revealed new features of D. sibericus, D. murinus, and R. tsutsugamushi biology, mainly a very active movement in the cell. In contrast to D. sibericus, development of D. murinus and R. tsutsugamushi in cells is characterized by severe irritation of the infected cells early in the infection, a greater speed of movement of rickettsiae and their active release from the affected cells, as well as the development of necrobiotic changes in the latter. The mitotic activity of the cells increased early in cultures infected with Cox. burneti, R. prowazeki, D. sibericus, and T. tsutsugamushi. Subsequently, cell nuclei shrink and different cytotic changes develop in various rickettsia. Studies on the metabolism of the affected cells revealed activation of nucleic metabolism and redox enzymes associated with mitochondria in the course of the first 3 days followed by a low activity in 5 postinfection days. The lysosomal apparatus of the cells underwent drastic changes and the activity of acid phosphatase increased markedly with further elevation in the permeability of lysosomal membranes.
