The Results of Some Comparative Experimental Investigations of L‐forms of Bacteria and Mycoplasma*

Abstract

It is well known that the differentiation of mycoplasma and L-forms of bacteria is very difficult because of their biological similarity. Therefore, the aim of our investigations was to find possible criteria for differentiating between these microorganisms. Hence, we conducted the following comparative investigations of the morphology of L-forms of bacteria and mycoplasma, their antigenic peculiarities, behavior in tissue cultures and their capacity to produce a certain pathogenic effect in experimental infection of susceptible species of animals. A short review of these works is given in this paper. MaterialsIn all of the studies, the same cultures of stable L-forms and mycoplasma were used.The following L-forms were used: L-form of Salmonella typhi ( N 152 L), Gform of p-hemolytic Streptococcus group A obtained experimentally from Streptococcus type 2 (N 10-S) and its reversed L-form, two strains of L-forms of streptococci (N 409 L and N 406 L) isolated by us from the blood of rheumatic patients' and their reversed forms ( N 409r and N 406r). All these cultures of L-forms have now lost the capacity to revert. In addition, L-forms of the known strains of streptococci (AEDL) and gl8L and their parental cultures were tested (AED) type 12 and (g18) of the type 19.The following mycoplasma cultures were used : Mycoplasma hominis 1, M . salivarium (cultures received from Dr. D. G . ff Edward, Kent, England), M . laidlawii, M . aguluctiae (cultures received from Dr. W. Kohler, Jena, Germany), mycoplasma isolated from tissue cultures Hep-2, CMH, HeLa, A-1. The methods used for these studies are given briefly in each section. ResultsThe comparative investigations of the morphology of L-forms and mycoplasma were conducted by phase-contrast microscopy combined with Zeitraffer filming. This technique permits observation of the peculiarities of microstructures and their development and multiplication. The cultures were inoculated on proper media under optimal conditions of growth for L-forms and mycoplasma and observed with different types of cameras.As is known, the absence of a rigid cell wall in the L-forms of bacteria and mycoplasma conditions their polymorphism and plasticity. In the structure of the colonies, we, as well as other scientist^,"^ observed granular and globular *

Mycoplasmas and cell cultures.

“…The mycoplasmainfected cells were also less sensitive to exogenously supplied interferon. However, other investigators have found some suggestion of increased production of interferon when mycoplasma and virus are present together (25,88,205).…”

“…The effects of mycoplasmas on the morphology of contaminated cell lines range from zero (26,135,155,156) to increase in cytoplasmic granularity and retardation of growth (91,185,186) to frank cytopathology (3,9,24,27,54,61,66,76,84,88,137,185,186). The mycoplasmas may have such a drastic effect upon the cell cultures that the whole cell population lyses (92, 94).…”

“…Kagan et al (88,89) showed that arbovirus replication was inhibited when grown in mycoplasma-contaminated cells. However, Rouse et al (157,158) noted that the titer of dengue type 2 virus (an arbovirus) was not affected when grown in mycoplasma-contaminated cells.…”

Mycoplasma-Associated Induction of Interferon in Ovine Leukocytes

“…Several studies have demonstrated that mycoplasmas may enhance (43), depress (36), or have no effect on (2) the induction of interferon by various agents in tissue culture. Similar diverse effects of mycoplasmas on viral replication are well documented (2,16,24,36). The ability of A. Iaidlawii to induce interferon in mammalian cells should be viewed with some concern due to increasing frequency of isolation of this and other mycoplasmal species from cell cultures (18,38).…”

“…As with A. laidlawii, BTV elicited higher levels of interferon in leukocytes from ewe #7 than in cell cultures from ewe #46. The interferon induced by A. Iaidlawii was usually not detectable until 48 h postinoculation, whereas that induced by BTV was apparent at 24 h.…”