Evaluation of an indirect immunoperoxidase test for identification of acholeplasma and mycoplasma

Exosomes Secreted by Umbilical Cord Blood-Derived Mesenchymal Stem Cell Attenuate Diabetes in Mice

Mesenchymal stem cell (MSC) therapy is an innovative approach in diabetes due to its capacity to modulate tissue microenvironment and regeneration of glucose-responsive insulin-producing cells. In this study, we investigated the role of MSC-derived exosomes in pancreatic regeneration and insulin secretion in mice with streptozotocin-induced diabetes. Mesenchymal stem cells (MSCs) were isolated and characterized from umbilical cord blood (UCB). Exosomes were isolated and characterized from these MSCs. Diabetes was induced in male C57Bl/6 mice by streptozotocin (STZ; 40 mg/kg body weight, i.p.) for five consecutive days. The diabetic mice were administered (i.v.) with MSC (1 × 105 umbilical cord blood MSC cells/mice/day), their derived exosomes (the MSC-Exo group that received exosomes derived from 1 × 105 MSC cells/mice/day), or the same volume of PBS. Before administration, the potency of MSCs and their exosomes was evaluated in vitro by T cell activation experiments. After day 7 of the treatments, blood samples and pancreatic tissues were collected. Histochemistry was performed to check cellular architecture and β cell regeneration. In body weight, blood glucose level, and insulin level, cell proliferation assay was done to confirm regeneration of cells after MSC and MSC-Exo treatments. Hyperglycemia was also attenuated in these mice with a concomitant increase in insulin production and an improved histological structure compared to mice in the PBS-treated group. We found increased expression of genes associated with tissue regeneration pathways, including Reg2, Reg3, and Amy2b in the pancreatic tissue of mice treated with MSC or MSC-Exo relative to PBS-treated mice. MicroRNA profiling of MSC-derived exosomes showed the presence of miRs that may facilitate pancreatic regeneration by regulating the Extl3-Reg-cyclinD1 pathway. These results demonstrate a potential therapeutic role of umbilical cord blood MSC-derived exosomes in attenuating insulin deficiency by activating pancreatic islets' regenerative abilities.

Development of a recombinant antigen for antibody-based diagnosis of Mycoplasma bovis infection in cattle

Mycoplasma bovis induces various clinical manifestations in cattle, such as mastitis, arthritis, and pneumonia. We have evaluated the immunoreactivity of three variable surface proteins (Vsps) of M. bovis, namely VspA, VspB, and VspC, with sera collected from herds with mycoplasmosis or from cattle experimentally infected with M. bovis. Western blot analysis revealed that the Vsps are the predominant antigens recognized by the host humoral response during M. bovis infection. The immunoreactivity of VspA, VspB, and VspC with host antibodies was independent of the clinical manifestations, the geographical origin of the M. bovis isolates, the mode of infection, and the animal's history. Moreover, the results showed that Vsp-specific host antibodies can be detected about 10 days after experimental infection and for up to several months. The full-length or truncated versions of the VspA product were overexpressed in Escherichia coli as fusion proteins (FP-VspA). Recombinant products showed strong immunoreactivity with the Vsp-specific monoclonal antibodies 1A1 and 1E5, with the corresponding epitopes localized at the VspA N-terminal and C-terminal ends, respectively. Anti-M. bovis sera of cattle naturally or experimentally infected also strongly recognized the full-length FP-VspA. The seroreactivity of sera collected from cattle between 6 and 10 days after experimental infection was weaker with truncated versions of VspA lacking the 1E5 epitope than with the full-length VspA or the truncated versions lacking the 1A1 epitope. Overall, the results indicate that the Vsps, despite their inter- and intraclonal variability, may be applied as target antigens in serodiagnostic assays for epidemiological studies.

A filter immunobinding technique for the rapid detection and simultaneous identification of avian and bovine mycoplasmas

A filter immunobinding (FIB) method was developed for the detection and identification of mycoplasmas. Type strains of a total of 18 avian and bovine mycoplasma species propagated in broth media were diluted and immobilized on a nitrocellulose membrane as antigens for investigating the specificity with rabbit hyperimmune sera. Non-specific FIB reactions were easily eliminated by the procedure of absorbing rabbit hyperimmune sera in the broth. Absorbed rabbit hyperimmune sera exhibited clear species-specificity with mycoplasma antigens by the FIB. These specific reactions always agreed with the results of identification by tests of biochemical properties and growth inhibition for the isolates of M. bovirhinis, M. bovis, M. columbinum, M. columborale, M. gallisepticum and M. synoviae. Some bovine mycoplasma species, which were impossible to identify by growth inhibition test, because of their strong production of film and spots on the agar, specifically reacted with absorbed rabbit hyperimmune sera against M. bovis in the FIB. The detection limit of mycoplasmas by this method was about 10(4)-10(5) colony-forming units/ml, which is lower than that of colony determination on agar. The FIB seems to be a useful technique for rapid detection and simultaneous identification of mycoplasmas.

Effect of mixed infection of Mycoplasma gallinarum and Newcastle disease virus (F strain) on the tracheal epithelium of village chickens

The effects of a mixed infection of Mycoplasma gallinarum and Newcastle disease virus (F strain) on the tracheal epithelium of village chickens were investigated and observed by scanning electron microscopy. Day-old village chicks were vaccinated intranasally with F strain Newcastle disease virus and inoculated intratracheally on the same day with 10(8) colony forming units of M gallinarum. In another study the chicks were vaccinated and then infected with M gallinarum seven days later. The first group of chicks was euthanased three, seven, 10, 14 and 21 days after vaccination and infection and the vaccinated chicks were euthanased three, seven, 10 and 14 days after infection. In the chicks vaccinated and infected on the same day, major alterations to the tracheal epithelium were visible three days later. There were fewer ciliated cells and the borders of the non-ciliated cells were prominent. Several depressions had formed in the epithelial surface. At higher magnification, clumps of microvilli were visible on some of the non-ciliated cells. Seven days after vaccination and infection, the tracheal epithelium appeared normal, with an increase in the numbers of ciliated cells, although raised borders were observed on the non-ciliated cells in some areas. No clumping of microvilli or depressions in the epithelial surface were observed. In the chicks infected seven days after vaccination, the tracheal epithelium appeared normal with no visible changes on its surface.

Variant colony surface antigenic phenotypes within mycoplasma strain populations: implications for species identification and strain standardization

Immunobinding assays with mycoplasma colonies on agar plates (immunofluorescence and immunoperoxidase techniques) or with imprints of colonies transferred to solid supports (colony immunoblotting) are widely used as standard diagnostic tests for serological species identification of mycoplasma isolates. However, in light of the high rate of variability of surface antigens in many mycoplasmas, diagnostic data obtained with these techniques require a more critical evaluation. In this report, we demonstrate with some examples that mycoplasma surface variability based on alterations in expression, in size, and in surface presentation of integral and peripheral membrane proteins may lead to misinterpretation of colony immunostaining reactions obtained by using specific monoclonal antibodies as well as conventional diagnostic hyperimmune sera. To more easily identify phenotypically mixed isolates or samples which contain more than one species, we have introduced some minor modifications of the colony immunoblot technique which provide sharp signals of positive as well as negative reactions and enable identification of cryptic epitopes. It is further demonstrated that because of the variability in colony surface antigenic phenotype, mycoplasma strains, including well-established reference and other prototype strains which are used under the same designation in many laboratories, can differ markedly in their antigen profiles and their potentially virulence-related surface properties, since they are usually purified by filter cloning and often propagated by subcultivation of randomly selected agar-grown subpopulations. We conclude from this study that because of this surface variability, the establishment of criteria for standardization of mycoplasma strains and diagnostic antisera is urgently required in order to obtain reproducible results in different laboratories.

Effect of Mycoplasma gallinarum on embryonated village chicken eggs

The effect of Mycoplasma gallinarum isolated from village chickens on embryonated village chicken eggs was investigated. Seven-, 10-, 12- and 18-day-old embryos were inoculated with medium containing 10(6) colony forming units of M gallinarum or with uninfected medium and incubated at 37 degrees C until they hatched. There was no significant difference between the infected embryos which failed to hatch and those which hatched or between them and the group inoculated with medium only. A much higher percentage of the eggs inoculated as 18-day-old embryos hatched than of those inoculated at seven, 10 and 12 days old. The hatchability of the uninoculated village chicken eggs used in the four trials ranged from 60 to 100 per cent. Mycoplasmas were isolated from the oesophagus, trachea and yolk of the infected chicks and from the dead-in-shell embryos.

Prevalence of mycoplasmas in the respiratory tracts of pneumonic calves

The prevalence of mycoplasmas in the respiratory tracts of 148 pneumonic calves originating from 25 herds in the Netherlands is reported. Four types of culture media were used to isolate mycoplasmas: solid modified Edward medium, 2 types of Friis media, and A7B differential agar medium. Mycoplasmas were isolated both from nasal swab specimens and lung lavage fluids collected from live calves and from nasal mucosa and lung tissue specimens collected post mortem. All of the mycoplasma strains isolated could be identified as either Ureaplasma diversum (isolated from 80% of 25 herds), Mycoplasma dispar (92%), M. bovirhinis (88%), M. bovis (20%), M. bovigenitalium (4%), M. arginini (16%), or M. canis (12%). Isolation rates of M. dispar and U. diversum were considerably higher from lung lavage fluids than from nasal swab specimens. M. bovis was detected only in fattening herds and not in dairy herds. The respiratory tracts of 75% of the calves examined contained at least 2 mycoplasma species. In total, 25 different combinations of mycoplasma species were detected in specimens collected from noses and lungs. The pathogenic species U. diversum and M. dispar had not been isolated before in the Netherlands.

Contagious bovine pleuropneumonia. A review

The prevalence, characteristics of the aetiological agent, clinical signs, pathological changes, pathogenesis, epizootiology, microbiological and serological diagnosis, prevention, and control of contagious bovine pleuropneumonia (CBPP), caused by Mycoplasma mycoides subspecies mycoides SC.type, are reviewed. New aspects of the disease are discussed. A renewed interest in this disease is important because of outbreaks in Southern Europe since 1980. When, at the end of 1992, the national borders of the countries of the European Community are abolished, it is conceivable that the disease will be introduced by cattle imported into CBPP-free countries.

Increased prevalence of Mycoplasma bovis in the Netherlands

The epidemiology, therapy, and prevention of M. bovis infections are briefly reviewed. In a survey begun in 1982, M. bovis was found frequently in the respiratory tract [corrected] of veal calves and beef cattle with respiratory problems. In replacement calves infected with respiratory disease in dairy herds, however, the organism has only been detected since 1986. Respiratory tract specimens collected from calves with respiratory disease were submitted for examination for M. bovis from 1986 to 1991 and originated from 83 herds. Mycoplasma bovis was detected in specimens from 59 of the herds, 20% of which were dairy herds and 80% fattening herds. Arthritis caused by M. bovis was observed in 12 herds until July 1991. Since 1976 when the first mastitis outbreak caused by M. bovis was diagnosed, M. bovis has caused 14 more outbreaks. The number of diseased cattle varied from 1 tot 16 per farm, and clinical signs of mastitis varied from mild to severe. In all instances the infection has been eradicated from the herds. Because M. bovis can cause great losses in intensively reared cattle herds, it is advisable to separate purchased veal calves and beef cattle from dairy cattle to prevent further spread of M. bovis.

Combination of immunofluorescence and immunoperoxidase techniques for serotyping mixtures of Mycoplasma species

We describe a method for the simultaneous identification of up to three Mycoplasma species by the use of contrast-labeled fluorescent antibodies against two species and peroxidase-labeled antibody against a third species. The procedure enabled the rapid identification of colonies of three artificially mixed avian Mycoplasma species on agar blocks and also mixtures of species in cultures from naturally infected chickens. Furthermore, it was possible to quantitate the components of a mixture of Mycoplasma gallisepticum, M. synoviae, and M. gallinarum. This new procedure offers an improvement over existing methods in terms of both speed and analytical capability.

Identification of ruminant mycoplasmas by dot immunobinding on membrane filtration (MF dot)

A simple method of species identification of ruminant mycoplasmas by dot immunobinding (MF dot) is described. Mycoplasmas from broth cultures were directly trapped onto the surface of low protein-binding affinity membranes by vacuum filtration. Specific polyclonal anti-mycoplasma sera were then applied. Mycoplasma-antibody complexes were then revealed by an enzyme conjugated anti-immunoglobulin. A positive reaction was indicated by the development of a color reaction when substrate was added. The method was tested on 22 type-strains representative of species, subspecies, types or yet unnamed serogroups of mycoplasmas isolated from ruminants. MF dot presented a specificity close to that which could be expected from the reference serological tests. The advantages of the MF dot over the other tests are utility, rapidity, ready standardization and it allows many samples to be treated simultaneously.

An improved method for the identification of Mycoplasma dispar

An indirect immunoperoxidase test is described for easy and reliable identification of Mycoplasma dispar. Cultures suspected of being M. dispar were grown on nitrocellulose filter papers and could be identified without having produced centre-forming colonies. These develop only after several passages in vitro and are required for standard identification procedures such as immunofluorescence or growth inhibition. It is to be expected that the method reported here could also be useful for the identification of other mycoplasma species forming centre-less colonies.

Elimination of Mycoplasma from cell cultures by means of specific bovine antiserum

Heifers were immunized against Mycoplasma arginini, M. fermentans, M. hyorhinis and M. orale and the antisera were applied for elimination of these species from cell cultures. From fifteen out of nineteen contaminated human and animal cell cultures the mycoplasmas could be eliminated by treating the cells with medium with 10% or 20% antiserum (eight cases) or antiserum combined with one or two antibiotics (six cases). In ten cases two treatments were sufficient, in four cases respectively four, six or eight (2 X) treatments were necessary, in one case antiserum combined with a heat treatment (42 degrees C) was successful. The efficacy of the treatment depended on the antibody titer of the serum, the contaminating mycoplasm species (M. arginini being more difficult to eliminate than the other three species) and the cells involved. The bovine sera were not cytotoxic, except for a slight toxicity for a mouse lymphoma cell line. The application of specific bovine antiserum for elimination of mycoplasmas is an easy and often successful method.

Rapid identification of mycoplasmas by indirect immunoperoxidase test using small square filter paper

The indirect immunoperoxidase test using small, square filter paper was used for rapid identification of mycoplasmas. Colonies of type strains of 22 mycoplasma species, 3 acholeplasma species, and three Ureaplasma diversum serogroups were stained by this test with high sensitivity and specificity. All of 49 isolates from bovine materials and cell cultures were easily identified by this test, and the results agreed with those obtained by growth inhibition test. Use of filter paper made it possible to add different kinds of antisera or conjugates to the same agar plate simultaneously and also to save antiserum and conjugate. This test proved to be a simple and useful technique for rapid identification of many mycoplasma species grown on agar medium.

Comparison of two methods for detection of mollicutes (Mycoplasmatales and Acholeplasmatales) in cell cultures in the Netherlands

A total of 1949 cell cultures was tested for contamination with mollicutes by cultivation on and in mycoplasma media, 25.7% of the cell cultures was positive, 243 strains of Mycoplasma hyorhinis were isolated. Furthermore, mainly M. arginini and M. orale were detected, less often Acholeplasma laidlawii, M. fermentans and M. pneumoniae. Optimal conditions for isolation were discussed. About one third of 217 hybridoma cultures and two third of 57 myeloma cultures proved to be contaminated, all with M. hyorhinis. A DNA fluorochrome staining method (DAPI-test) was compared to cultivation for testing 1039 cell cultures. The efficiency of the DAPI-test could be estimated to be about 96% that of cultivation about 89%, but cultivation is more specific. The highest assurance is obtained when both methods are applied.

Retrospective confirmation of Mycoplasma infection by the immunoperoxidase technique

Rat tissues embedded in paraffin blocks stored for 8-10 yr were sectioned for immunoperoxidase staining. Sections of lung, trachea and endometrium of 22 of 32 rats that had exhibited clinical symptoms of mycoplasmal pneumonia prior to euthanasia, and whose organs had shown gross lesions suggesting mycoplasmal infection on necropsy, demonstrated the presence of Mycoplasma pulmonis organisms by the immunoperoxidase technique in one or more of these tissues.

Detection and speciation of common cell culture mycoplasmas by an enzyme-linked immunosorbent assay with biotin-avidin amplification and microporous membrane solid phase

An enzyme-linked immunosorbent assay (ELISA) was developed in order to serve in detecting and speciating mycoplasmas isolated from cell cultures. Its main features included a biotin-streptavidin amplification step and a solid phase consisting of a microporous membrane. Cell samples in the form of suspensions were applied to nitrocellulose or ion exchange membranes immobilized in commercially-available microtiter, multiwell manifolds. The blocking buffer contained 1% purified alpha-casein. The primary antibodies were monoclonal and the polyclonal secondary antibody was biotinylated. The enzyme utilized was streptavidin-horseradish peroxidase. The substrate-dye complex consisted of either 4-chloro-1-naphthol and hydrogen peroxide or ortho phenylene diamine (OPD) and hydrogen peroxide. The presence of homologous antiserum in the reaction sequence gave clearly visible, colored reactions on the membrane when 50 ul with approximately 10(5) or more cfu/ml were present. This new biotin-avidin microporous membrane (BAMM-ELISA) test can be used both to detect mycoplasmas and to speciate them. The BAMM-ELISA is simple, rapid, sensitive, specific and economical. As such, it has potential for aiding in the control of mycoplasma contamination in cell culture, and could prove useful in clinical diagnostic applications as well.

Rapid and simple identification of mycoplasmas by immunobinding

A simple and rapid method of species identification of mycoplasmas by immunobinding assay is described. Small amounts of antigen of supernatant from cell cultures, broth cultures or clinical specimens were spotted onto nitrocellulose paper. This was followed by application of specific anti-mycoplasma antisera. After incubation, an enzyme-conjugated antiserum against the first antiserum was applied. A positive reaction was indicated by the development of intense blue color reaction when substrate was added. This method identified mycoplasma species with monoclonal and polyclonal antibodies. It detected 9.3 X 10(3) - 7.5 X 10(4) CFU/ml of organisms depending on mycoplasma species. For identification of mycoplasma, ureaplasma, acholeplasma and spiroplasma species, this assay is useful and rapid compared with other serological methods. In limited studies, the method correlated with microbiological assay of clinical specimens for Mycoplasma pneumoniae.

Serotyping of Ureaplasma urealyticum by immunoperoxidase assay

The immunoperoxidase method was applied to the identification of Urea-plasma urealyticum serotypes. The assay used highly diluted antisera and could be run directly on primary plate isolates. It was ideal for detecting and identifying mixed serotypes because stained and unstained colonies could be visualized simultaneously by conventional light microscopy. Antisera run against eight serotypes revealed one-way cross-reactions between serotypes 3 and 5 and antiserum to 2, and between serotype 4 and antiserum to 8, at dilutions of less than 1:150. This cross-reactivity could be diluted out at the optimal antiserum dilution for the immunoperoxidase assay, but not for the growth inhibition assay or immunofluorescence test. The immunoperoxidase assay therefore proved ideal for serotyping U. urealyticum.

A direct comparison of procedures for the detection of mycoplasma in tissue culture

Mycoplasma contamination of cell cultures has been shown to perturb a number of immunologic parameters. Because such contamination is almost always introduced in the laboratory, the immunologist requires a procedure to screen his cell lines frequently for mycoplasma. Two procedures recently described for the detection of mycoplasma in cell cultures, the uridine-uracil incorporation procedure and a direct fluorescent assay, were compared with the standard procedures of agar culture and transmission electron microscopy. The results with uridine-uracil incorporation were totally non-concordant with those of any of the other 3 procedures and, moreover, were inconsistent through serial assays on the same cell culture. In contrast, the direct fluorescent assay, using the fluorochrome Hoechst 33258, yielded consistent results in full agreement with the agar culture data. Since the fluorescent assay is rapid and has discriminatory capability at least equivalent to that of agar culture, it would appear to be the method of choice for routine screening of cell cultures for mycoplasma.