Growth on artificial medium of an agent associated with atypical pneumonia and its identification as a PPLO

Mycoplasma-associated induction of interferon in ovine leukocytes

A mycoplasmal species, Acholeplasma laidlawii, isolated as a contaminant from a fetal lamb kidney cell line, was shown to be associated with the induction of interferon in cultures of ovine peripheral blood leukocytes. Broth cultures of the mycoplasma induced between 20 and 230 U of interferon per ml in leukocytes from two adult ewes. The amount of interferon produced correlated with the inoculum size of mycoplasma. Interferon production was associated with replication of the mycoplasma in the leukocyte cultures. Interferon was not induced by sterile mycoplasmal broth, a cell-free filtrate of the mycoplasmal cultures, or heat-inactivated mycoplasmas. The antiviral substance was characterized as interferon by the usual criteria.

Antibody to Mycoplasma pneumoniae in nasal secretions and sputa of experimentally infected human volunteers

After experimental infection with Mycoplasma pneumoniae, 42% of 67 volunteers developed a threefold or greater rise in antibody in nasal secretions as measured by radioimmunoprecipitation. Development of an antibody increase in sputum was detected more often, i.e., in 73% of the volunteers. Each of the antibody increases involved immunoglobulin (Ig) A. Twelve rises in IgG antibody were detected in the specimens which exhibited a rise in IgA antibody. In almost every instance the rise in IgA antibody exceeded that seen with IgG antibody. Analysis of the response to experimental challenge with M. pneumoniae of volunteers with different levels of preexisting respiratory tract IgA antibody suggested that this secretory antibody was related to host resistance to M. pneumoniae disease. Further, respiratory tract IgA antibody appeared to be more directly related to host resistance than was antibody in serum.

Detection and characterization of defective mycoplasmacidal antibody produced by rodents against Mycoplasma arthritidis

A procedure has been developed for the detection of mycoplasmacidal antibody in the serum of rats and mice infected with Mycoplasma arthritidis. Antibody activity can apparently be measured only by using resting mycoplasma cells. The reaction is complement dependent and is usually complete within 3 h. Early antibody (5 days) could be detected only within the immunoglobulin (Ig)M fraction, whereas late antibody (42 days) is found within the IgG fraction. The mycoplasmacidal antibody was highly specific and cross reactions were not observed with other mycoplasma species. Antibody activity could be removed from serum by absorption with either viable or nonviable M. arthritidis. Cidal antibody produced by rats against other mycoplasma species was active against both resting and multiplying cells. Mycoplasmacidal antibody against M. arthritidis was detected in rats 2 days after injection of the organisms and persisted at least through 300 days. Mice usually developed antibodies by 3 days after injection of the organisms and moderate titers have been observed for as long as 487 days. Since viable mycoplasmas can persist in the peripheral circulation in the presence of antibody, it is likely that viable mycoplasma-antibody complexes are also present.

Synchronization of mitochondrial DNA synthesis in Chinese hamster cells (line CHO) deprived of isoleucine

Mitochondrial DNA (mit-DNA) synthesis was compared in suspension cultures of Chinese hamster cells (line CHO) whose cell cycle events had been synchronized by isoleucine deprivation or mitotic selection. At hourly intervals during cell cycle progression, synchronized cells were exposed to tritiated thymidine ([(3)H]TdR), homogenized, and nuclei and mitochondria isolated by differential centrifugation. Mit-DNA and nuclear DNA were isolated and incorporation of radioisotope measured as counts per minute ([(3)H]TdR) per microgram DNA. Mit-DNA synthesis in cells synchronized by mitotic selection began after 4 h and continued for approximately 9 h. This time-course pattern resembled that of nuclear DNA synthesis. In contrast, mit-DNA synthesis in cells synchronized by isoleucine deprivation did not begin until 9-12 h after addition of isoleucine and virtually all [(3)H]TdR was incorporated during a 3-h interval. We have concluded from these results that mit-DNA synthesis is inhibited in CHO cells which are arrested in G(1) because of isoleucine deprivation and that addition of isoleucine stimulates synchronous synthesis of mit-DNA. We believe this method of synchronizing mit-DNA synthesis may be of value in studies of factors which regulate synthesis of mit-DNA.

Membrane changes and adenosine triphosphate content in normal and malignant transformed cells

Transformed fibroblasts had a low content of ATP when grown at a high cell density and a high content of ATP when grown at a low cell density. Concanavalin A agglutinated transformed cells with a low, but not those with a high, ATP content. Transformed cells with a high ATP content gained agglutinability after ATP depletion by inhibitors of the energy-generating systems, and those with a low ATP content lost their agglutinability after restoration of a high ATP content by glucose. Fixation of the surface membrane by formaldehyde, glutaraldehyde, or LaCl(3), inhibited agglutination of cells with an ATP content that allows agglutination. Normal fibroblasts grown at a high or a low cell density were not agglutinated by concanavalin A. Depletion of the cellular ATP content of normal cells induced agglutination only in cells grown at a high, but not at a low, cell density. A similar number of concanavalin A molecules was bound to the surface membrane of agglutinating and nonagglutinating fibroblasts. It is suggested that a high content of ATP inhibits the movement of concanavalin A binding sites, and that a low content of ATP allows, in transformed cells, a new distribution of binding sites to form the clusters required for cell agglutination. Agglutinability of transformed cells is determined by ATP content, and in normal cells changes in the content of ATP are by themselves not sufficient to induce agglutination. Transformed cells, therefore, do not have a control, presumably for membrane stability, that exists in normal cells.

Macrophage nonimmunologic recognition: target cell factors related to contact inhibition

Activated mouse macrophages were not cytotoxic to contact-inhibited nontumorigenic 3T3 fibroblasts, but caused marked destruction to non-contact-inhibited, tumorigenic 3T12 and simian virus 40-transformed fibroblasts. Nonimmunologic recognition and destruction of target cells by activated macrophages is independent of altered morphology, abnormal karyotype, and ability for continuous multiplication in vitro-all characteristics of 3T3 fibroblasts. A modification e f the target cell surface that results in a high in vitro saturation density, agglutinability by plant lectins, and tumorigenicity appears to evoke a cytotoxic response by activated macrophages.

Interaction of Mycoplasma arthritidis and other mycoplasmas with murine peritoneal macrophages

Neither mouse nor rat peritoneal macrophages were able to kill Mycoplasma arthritidis to any observable degree in the absence of specific hyperimmune rabbit antiserum. Although convalescent mouse and rat serum were somewhat inhibitory to M. arthritidis in the absence of macrophages, these sera did not promote active phagocytosis by peritoneal macrophages. In fact, the macrophages appeared to protect the mycoplasmas against the inhibitory effects of the antisera by stimulating their growth. Hyperimmune rabbit antiserum against M. arthritidis initiated phagocytic action and resulted in a 50-fold decrease in numbers of viable mycoplasmas by 6 h. In contrast with M. arthritidis, M. pulmonis rapidly adsorbed to the surface of peritoneal macrophages. Upon addition of specific rabbit antiserum, a rapid decrease in viable organisms occurred, and a more complete destruction of organisms ensued in comparison with M. arthritidis. M. gallinarum, as with M. arthritidis, did not adsorb to the macrophages to any great extent. Phagocytic action was observed only in the presence of homologous rabbit antiserum and was not marked until after 6 h of incubation.

The association of viral and bacterial respiratory infections with exacerbations of wheezing in young asthmatic children

The relationship between exacerbations of wheezing and infection of the respiratory tract was studied prospectively in 32 young hospitalized asthmatic children. Of 139 episodes of wheezing, 58 (42 per cent) were associated with identifiable viral infections. There were 25 respiratory syncytial virus infections; wheezing occurred in 24 of these and pneumonia in 13. Parainfluenza type 2 infection appeared to be next most likely to be associated with wheezing, followed by coronavirus infection. Influenza A. (Hong Kong) was not associated with wheezing in any of the children. Infection with “pathogenic” bacteria was not statistically associated with wheezing.

Fate of intravenously injected Mycoplasma arthritidis in rodents and effect of vaccines

Virulent Mycoplasma arthritidis strain 158 P10 was rapidly eliminated from the peripheral circulation of rats and mice during the first 2 h after intravenous injection of the organisms. Characteristically after this time, the numbers of viable organisms remained remarkably constant through 48 to 72 h. The inability to clear the remaining mycoplasmas was not due to reticuloendothelial blockade but appeared to indicate the presence of a certain number of cells which were resistant to the clearance mechanism. Rat blood was usually devoid of mycoplasmas at 6 days and mouse blood was sterile by 14 days. An occasional transient mycoplasmemia occurred after these times. Avirulent M. arthritidis strain H606 was cleared more rapidly from rats in which it is non-arthritogenic. Different, but characteristic, clearance curves were obtained in mice using M. hominis, M. bovirhinis, and M. pulmonis. Active immunization procedures resulted in enhanced clearance of virulent M. arthritidis from rats. These procedures were less successful in mice. The results of passive immunization of normal rats and mice using convalescent serum indicated the presence of a serum factor which greatly enhanced clearance from rats but had only minimal effects in mice. This serum factor could not be correlated with metabolic-inhibiting antibody. Lymphocytes taken from convalescent rats enhanced the clearance rates of recipient rats. Mouse convalescent lymphocytes were without effect. The results indicated that mice are less able to control long-term infection by M. arthritidis than are rats.

Ultrastructural lesions in Mycoplasma pneumoniae membranes produced by antibody and complement

Lesions in Mycoplasma pneumoniae membranes were produced by antibody and either human or guinea pig complement and were observed by electron microscopy after negative staining. These defects measured approximately 9.0 to 10.0 nm in diameter-slightly more for human complement than for guinea pig complement. The development of these small lesions was accompanied by a decrease in the viability of the organism.

[Factors influencing the susceptibility of mice to Mycoplasma arthritidis]

Concentrated broth constituents markedly enhanced the development of abscesses after subcutaneous injection of Mycoplasma arthritidis. Under appropriate conditions, both virulent and avirulent strains of M. arthritidis produced toxic effects in mice, as detected by the development of necrotic abscesses and death of the animals. The treatment of mice at birth with M. arthritidis antigens rendered the animals more susceptible to infection with M. arthritidis later in life, as evidenced by increased arthritis after intravenous injection. The injection of M. arthritidis into pregnant mice resulted in a high incidence of abortions. Comparative studies using different mouse strains showed that DBA mice were the most susceptible and BALB/c and C57BL mice were the most resistant to infection by M. arthritidis.

Differences in the binding of fluorescent concanavalin A to the surface membrane of normal and transformed cells

The binding of fluorescein-conjugated Concanavalin A to the cell surface has been studied in normal and transformed cells in interphase and mitosis. Binding to the cell surface was in the form of an incomplete ring of fluorescence, and the binding was inhibited by alpha-methyl-D-mannopyranoside. All the cells were fluorescent when treated with 25-250 mug/ml of fluorescent Concanavalin A. With 10 mug, the cells were all fluorescent after 30 min of binding, but after 0.5-5 min with 10 mug or 30 min with 1 or 2.5 mug, transformed interphase cells showed a higher percentage of cells with surface fluorescence than did normal interphase cells. Trypsinized normal and transformed interphase cells showed the same fluorescence. Binding with 2.5 mug at 4 degrees instead of at 24 degrees , gave a higher percentage of fluorescent cells with trypsinized than with untrypsinized transformed cells. Mitotic normal cells were similar to transformed interphase cells, whereas mitotic transformed cells were intermediate between normal and transformed interphase cells. The results indicate that the use of low concentrations of fluorescent Concanavalin A can show differences in surface fluorescence between normal and transformed, interphase and mitotic, and trypsinized and untrypsinized cells. It is suggested that the observed differences in fluorescence can be explained by differences in affinity of the lectin binding sites and/or differences in the clustering of sites.

Virus deoxyribonucleic acid sequences in subdiploid and subtetraploid revertants of polyoma-transformed cells

Polyoma-transformed cells can revert in the properties characteristic of transformation, although they maintain the polyoma-specific T antigen. Transformed cells contain the same number of copies of polyoma virus deoxyribonucleic acid (DNA) per cell (eight) as revertants with a subdiploid or a subtetraploid chromosome number. The results indicate that the duplication of chromosomes in the subtetraploid revertants did not include the chromosomes that carry the viral genome. The virus DNA in both transformed and revertant cells was associated with high-molecular-weight cell DNA. Reversion of the properties of transformed cells was, therefore, not associated either with a decrease in number of virus DNA copies per cell or with a lack of association of the virus DNA with cell DNA.

Tetrazolium agar overlay in test for Mycoplasma pneumoniae

In this rapid presumptive test for Mycoplasma pneumoniae, subculture is not required, and tetrazolium reduction is evident in 1 hr or less.

Etiology of chronic pneumonia in rats and a study of the experimental disease in mice

The lungs of conventional rats with chronic pneumonia contained Streptobacillus moniliformis and Mycoplasma pulmonis. These organisms singly and in combination failed to produce lung disease when inoculated into specific pathogen-free rats. On the other hand, diseased lung homogenate not containing cultivable organisms caused a chronic pneumonia when inoculated into specific pathogen-free rats. The organism involved was seen by electron microscopy and is morphologically indistinguishable from the grey lung agent of Andrewes and Glover and Nelson's enzootic bronchiectasis "virus." All of these agents have morphological and biological properties which indicate close relationship to the mycoplasmas. However, we failed to culture them either in tissue cultures or on inanimate media and conclude that a group of highly fastidious mycoplasma-like agents are a cause of chronic pneumonia in rodents.

Mycoplasma-virus interrelationships in mouse tracheal organ cultures

The effects produced by single and mixed infections with Mycoplasma pulmonis and influenza A/PR-8 virus were studied in mouse tracheal organ cultures. M. pulmonis multiplied in the tracheal organ cultures, producing inhibition of ciliary activity and histologic tissue damage. The organism grew in close association with the cell membranes but did not appear to attach directly to the membranes or the cilia. Influenza A virus also replicated in tracheal organ cultures, producing ciliary inhibition and more extensive cytopathologic changes. Virus particles were seen by electron microscopy to attach to and cause clumping of the cilia. Simultaneous infection of the organ cultures with mycoplasma and virus resulted in more rapid inactivation of ciliary activity and greater tissue damage than occurred when the cultures were infected with only mycoplasma or virus. Presence of the virus appeared to have no effect on the growth of the mycoplasma; however, the mycoplasma partially interfered with virus replication.

Human diseases associated with mycoplasms. With an appendix on simple culture techniques

The mycoplasmas (formerly called pleuropneumonia-like organisms, or pplo) are a group of pleomorphic micro-organisms characterized by lack of cell wall and ability to form colonies on agar resembling tiny fried eggs. They have been recognized as pathogens of lower mammals since 1898. Of the more than 40 known veterinary species, many are pathogens, commonly causing pneumonia, arthritis or arteritis. Of the mycoplasmas found in man, Mycoplasma pneumoniae is the only well established human pathogen. It is responsible for a variety of respiratory syndromes, of which the most frequently recognized is cold agglutinin-positive atypical pneumonia. Hematologic, neurologic and dermatologic complications of this infection have been noted. M. hominis has been implicated as a causative factor in various febrile complications of pregnancy, such as septic abortion and amnionitis. T-strain mycoplasmas are ubiquitous in the human genitourinary tract, but attempts to link their presence to disease have thus far been unsuccessful. Mycoplasmas also have been associated with neoplastic disease and with rheumatoid arthritis. The validity of these latter findings is unclear, and additional study is needed.

Oral mycoplasmas in Sjögren's syndrome

Mycoplasmas were sought in the salivary secretions and minor salivary gland tissue of 26 patients with Sjögren's syndrome or the allied sicca complex. A mycoplasma (M. orale type 1) was recovered from the stimulated parotid saliva of only one case. Possible mechanisms of mycoplasmal cell damage in this and allied disorders are considered and some future lines of investigation are suggested.

A specific metabolic activity on the surface membrane in malignant cell-transformation

The carbohydrate-binding protein, Concanavalin A (Con A), binds to glucose- or mannose-like sites on the cell-surface membrane. Unless the cells are treated with trypsin, this protein agglutinates malignantly transformed cells, but not normal cells. The transformed cells were agglutinated at 24 degrees C but not at 4 degrees C. Transformed and normal cells treated with trypsin were agglutinated at both 24 degrees C and 4 degrees C with high concentrations of Con A (500 mug/ml), but only at 24 degrees C with low concentrations (5 mug/ml). The same number of Con A molecules were bound to normal and transformed cells at both temperatures. The results indicate that the site for Con A on the surface membrane contains two activities, a component that binds Con A molecules (B) and a component that determines agglutination (A). B is not temperature sensitive and is active in normal and transformed cells, whereas A, which is temperature sensitive, is in an active form only in transformed cells. A can be activated by trypsin, and the increased activity per cell allows agglutination at 4 degrees C with a high, but not with a low, concentration of Con A. Agglutination of transformed cells by wheat-germ agglutinin, which binds to N-acetyl-D-glucosamine-like sites, and by soybean agglutinin, which binds to N-acetyl-D-galactosamine-like sites, was not temperature sensitive. Thus, the temperature-sensitive component A is specific for Con A, and malignant transformation of normal cells, which results in agglutinability by Con A, is associated with the activation of a specific temperature-sensitive activity on the surface membrane.

Antibiotic sensitivities of oral mycoplasma

Antibiotic sensitivities of five human species and one saprophytic species of mycoplasma were determined by the disk method. All were resistant to the antibiotics that act on cell walls. All were sensitive to the tetracyclines, chloramphenicol, kanamycin, and neomycin. Only Mycoplasma pneumoniae and Mycoplasma laidlawii B were sensitive to erythromycin, oleandomycin, streptomycin, and dihydrostreptomycin.

Chronic proliferative arthritis of mice induced by Mycoplasma arthritidis. I. Induction of disease and histopathological characteristics

Mice injected intravenously with Mycoplasma arthritidis developed a chronic arthritis which persisted through at least 269 days. Rats similarly treated developed an acute short-term infection. The mouse disease was characterized by periods of remission and exacerbation and was proliferative in nature, gradually spreading to adjacent joints. M. arthritidis strain 158 P10 was found to be less arthritogenic for mice than for rats, but further passage of this strain in mice substantially increased its virulence. Unlike rats, mice appeared to be susceptible to a "toxin" of M. arthritidis and they developed a necrotic spreading abscess after subcutaneous administration of the organisms. Histopathological studies revealed that mice varied greatly in the degree of joint inflammation, destruction, and repair. The disease was characterized by (i) an initial acute phase with infiltration of the articular and periarticular tissues with polymorphonuclear leukocytes and a mild hyperplasia of the synovial membrane; (ii) a mixed acute-chronic phase in which new areas of acute inflammation developed alongside areas of chronic lesions; (iii) a chronic phase followed which was characterized by massive synovial proliferation with mononuclear cell infiltration, irregularity in the articulating cartilage, pannus formation, and "punched out" defects in cortical bone near cartilagenous osseous junctures. The clinical course and histopathological characteristics of the chronic phase of mouse arthritis induced by M. arthritidis closely resembled those of rheumatoid arthritis of man.

Chronic proliferative arthritis of mice induced by Mycoplasma arthritidis. II. Serological responses of the lost and effect of vaccines

Complement-fixing antibodies were first detected in mice 7 days after intravenous injection with Mycoplasma arthritidis. Peak titers were observed at 21 days, and high levels of antibody persisted through 293 days. The metabolism-inhibiting antibody response was minimal. On fractionation of mouse sera, only 7S antibody was detected which first appeared at 12 days after injection and persisted throughout the experiment. In contrast, serum taken from rats injected with M. arthritidis contained predominantly 19S antibodies in the early stages of the disease which were gradually replaced with 7S antibodies. The intravenous injection of mice with M. arthritidis culture supernatant fluid had no effect upon their subsequent susceptibility to the arthritogenic effects of M. arthritidis, but this procedure appeared to delay the onset of abscess formation after the subcutaneous injection of M. arthritidis. Formalin-killed cells of M. arthritidis partially protected mice against the arthritis induced by M. arthritidis. Previous infections with M. arthritidis conferred partial immunity against the arthritogenic effects of the organism. Serum taken from convalescent mice at 41 days had a partial protective effect when used to immunize passively normal mice against M. arthritidis. However, rabbit anti-M. arthritidis serum which possessed higher complement-fixing and metabolism-inhibiting antibodies was without significant protective properties.

Effect of actinomycin D on the yield of lymphocytic choriomeningitis virus in baby hamster kidney cells

Depending on the concentration of actinomycin D, the yield of lymphocytic choriomeningitis virus in baby hamster kidney cells was either enhanced or inhibited.

Effect of serum on the yield of lymphocytic choriomeningitis virus in baby hamster kidney cells

The yields of the Armstrong and WE strains of lymphocytic choriomeningitis virus in baby hamster kidney (BHK) cells cultivated in either bovine, calf, fetal bovine, or horse serum were investigated. Lines of BHK cells were established in these sera. When the infected cell lines were observed by immunofluorescence, the per cent fluorescing cells for a given virus strain did not vary. However, for both strains, the extracellular virus yields per cell were significantly greater in the fetal bovine-cell line than in the other serum-cell lines.