Strains Of Mycoplasma Pulmonis Research Articles

Clearance of different strains of Mycoplasma pulmonis from the respiratory tract of C3H/HeN mice.

Pathogen-free C3H/HeN mice were exposed by aerosol to Mycoplasma pulmonis PG34(ASH), UAB 5782C, M1, UAB T, or UAB CT, and clearance of mycoplasmas from the nasal passages, trachea, and lungs was determined during the first 72 h postinoculation (PI). There were differences among strains of mycoplasmas in physical removal of organisms and in killing by nonspecific factors in the nasal passages and trachea. The avirulent strain, PG34(ASH), was quickly removed from the nasal passages and trachea. Physical removal of the other mycoplasmal strains occurred slowly, with 60 to 89% of the radioactive label remaining in the nasal passages and trachea even after 72 h. There were significant differences in killing among mycoplasmal strains by nonspecific host mechanisms in the nasal passages, trachea, and lungs. Strain UAB T was quickly killed at all levels of the respiratory tract. Strains UAB 5782C and M1 were killed at all three sites by 2 to 4 h PI. The most virulent strain, UAB CT, was killed much more slowly than the other strains. However, there was no statistical difference in the relative numbers of mycoplasmas present in the lungs at 72 h PI among strains UAB CT, UAB 5782C, and M1. These studies showed that the different mycoplasmal strains were cleared from the respiratory tract by different mechanisms and suggest that the differences in virulence among the mycoplasma strains can be explained, in part, by the differences in elimination of the organisms from the respiratory tract by nonspecific host defense mechanisms.

Differences in virulence for mice among strains of Mycoplasma pulmonis.

The mouse model of acute murine respiratory mycoplasmosis was used to screen 18 strains of Mycoplasma pulmonis for their ability to establish respiratory infections and produce gross lung lesions in the susceptible C3H/HeN mouse strain. All experiments were designed to minimize host, environmental, and microbial differences to ensure that experimental results would reflect differences in mycoplasmal virulence. There were differences in the 50% infectious dose (range, 3 X 10(2) to greater than 10(7) CFU) and the 50% gross pneumonia dose (range, 10(3) to greater than 10(7) CFU) among the 18 mycoplasmal strains. Only 10 strains (UAB CT, M1, UAB 5782C, UAB 6510, 66, UAB T, UAB 8145D, Nelson C, Peter C, and Negroni) established respiratory infections, and only 2 of the 10 strains (UAB CT and M1) produced gross lung lesions. Strains UAB CT, UAB T, M1, UAB 5782C, and PG34(ASH) were chosen for qualitative and quantitative evaluation of lung lesions in C3H/HeN and C57BL/6N mice. Lesion incidence and severity was dependent on the mycoplasmal strain and the mouse strain. Microscopic lesions varied among mycoplasmal strains and mouse strains in the amount of lymphoid infiltrate, neutrophilic exudate, and consolidation, as well as overall severity. The most virulent strain, UAB CT, produced acute pneumonitis in the 10(7) CFU dosage group and required a threshold dose of 10(3) CFU to consistently produce microscopic lung lesions. These results suggest that M. pulmonis virulence is multifactorial and different strains of mycoplasmas yield disease expressions that differ both qualitatively and quantitatively.

Colony opacity, hemadsorption, hemolysis, and mitogenicity are not associated with virulence of Mycoplasma pulmonis.

Colony opacity, hemadsorption and hemolysis of erythrocytes, and the ability of whole mycoplasmal cells to induce a blastogenic response when incubated with C3H/HeN or C57BL/6 mouse lymphocytes were examined for 18 strains of Mycoplasma pulmonis to determine if any of these characteristics could be associated with virulence in vivo. Although there were differences among strains in each of these characteristics, none of these parameters were associated with virulence.

Protein variability among strains of Mycoplasma pulmonis.

The proteins of Mycoplasma pulmonis were examined by two-dimensional polyacrylamide gel electrophoresis and immunoblotting. Comparison of profiles from silver-stained two-dimensional polyacrylamide gel electrophoresis of 18 strains of M. pulmonis allowed identification of five proteins that were strain variable. These variable proteins were not dependent on the medium used to grow the organisms and were shown by reaction with serum samples from naturally infected rats and mice to be produced in vivo and not to be medium components. Identification of strain-variable proteins may lead to an explanation of the differences in properties found among M. pulmonis strains.

Variation in the Virulence of Strains of Mycoplasma pulmonis Related to Susceptibility to Killing by Macrophages in vivo

The virulence of five strains of Mycoplasma pulmonis, as judged by their ability to survive in the respiratory tract and induce pneumonia in CBA mice, was related to the ability of viable organisms to persist in the peritoneal cavity. This appeared to be the result of differences in the ability of the strains to resist killing by peritoneal macrophages in vivo. It is suggested that resistance to phagocytosis by macrophages is an important determinant of virulence for M. pulmonis.

Plaque-forming factor produced by Mycoplasma pulmonis.

IT has been reported that mycoplasma viruses have been isolated from a number of different mycoplasmas—both Mycoplasma and Acholeplasma species. All the viruses isolated so far, however, only produce plaques on Acholeplasma laidlawii lawns and seem unable to infect the mycoplasma from which they were reputedly derived1. Some strains of Mycoplasma pulmonis are pathogenic for mice and others are not, and because pathogenicity may be attributable to the possession of a virus, we have searched for viruses that may infect M. pulmonis.

Electrophoretic patterns of strains of Mycoplasma pulmonis.

SUMMARY: Strains of Mycoplasma pulmonis, examined by polyacrylamide-gel electrophoresis of proteins extracted in a phenol-acetic acid-water solvent, gave patterns with reproducible differences. Some strains could be placed into groups, but a number could not be associated with any group. In all but one case a ‘basic M. pulmonis pattern’ was easily recognizable. This exception suggests that occasionally one might fail to recognize a strain of M. pulmonis by relying solely on the electrophoretic technique.

Serological heterogeneity of Mycoplasma pulmonis.

SUMMARY: Twelve stock and 15 freshly isolated strains of Mycoplasma pulmonis were examined and compared using four serological techniques. Complement fixation tests and inhibition of growth on solid medium showed that the strains were all M. pulmonis, although, with some strains, only one of these techniques gave an unequivocal result. These tests were confirmed to be specific only at a species level. Gel diffusion and metabolic inhibition techniques revealed heterogeneity of the strains at the subspecies level. The relationship between some strains was statistically significant and stable in vitro and some small groups could be defined. These serogroups bore no relationship to groups formed on the basis of protein patterns produced on polyacrylamide gel electrophoresis of strains of Mycoplasma pulmonis.

Relation between mycoplasmas and leukaemia and related diseases.

Forty-five bone marrow specimens from leukaemia patients and 40 marrows from nonleukaemia patients were cultured for mycoplasmas. No mycoplasmas were isolated. Sera from patients with leukaemia or reticuloses and from non-leukaemic subjects were examined for antibodies to the Negroni and 880 strains of Mycoplasma pulmonis and also to the K7, K10, and prototype (PG18) strains of M. fermentans. No significant differences were observed between the two groups of patients with respect to antibodies to these mycoplasmas. These findings support those of the majority of other workers in failing to show any relationship between mycoplasmas and neoplastic disease in man.

Phase-contrast and electron microscopy of murine strains of Mycoplasma.

Nelson, John B. (The Rockefeller University, New York, N.Y.), and Michael J. Lyons. Phase-contrast and electron microscopy of murine strains of Mycoplasma. J. Bacteriol. 90:1750-1763. 1965.-Two strains of Mycoplasma pulmonis (associated with infectious catarrh) on examination in fluid culture (20% horse serum-bouillon) by phase microscopy were highly pleomorphic, with many bacilliform elements and fewer coccoid ones. Motility, characterized by gliding of rods and spinning of spherical forms, was observed through the 9th subculture of one strain and the 15th of the second. Motile elements were not seen in later transfers and pleomorphism was reduced. One strain of M. neurolyticum (associated with conjunctivitis and encephalitis) was much less pleomorphic and showed neither bacilliform elements nor motility at any time. When examined by negative-contrast electron microscopy, organisms of this strain were found to have an average diameter of 0.7 mu and to possess a concentrated peripheral layer of cytoplasm and a central mass which may represent the cells' nuclear equivalent. The latter feature was not prominent in spherical forms of M. pulmonis. These cells, when observed after 48 hr of culture, showed evidence of the generation of new progeny cells in their central area. The filamentous or bacilliform cells of M. pulmonis were frequently serpentine in appearance, 2.0 to 3.0 mu in length and 80 to 250 mmu in width. They appeared to generate new cells from terminal buds from which outpouchings initially developed. Older cells, in the stationary phase, showed evidence of undergoing multipolar germination. Microtubules, about 60 mmu wide, were found in association with most filamentous cells from 48-hr cultures; fragments of membrane, studded with closely packed ribosomelike particles, were also found. There was no evidence of flagella or any specialized structure that could account for the observed motility of the organisms.