Antigenic analysis of three strains of Mycoplasma meleagridis of varying pathogenicity

Molecular cloning of a Mycoplasma meleagridis-specific antigenic domain endowed with a serodiagnostic potential

A recombinant phage library harbouring Mycoplasma meleagridis (MM) genomic DNA fragments was generated in the bacteriophage lambda gt11 expression vector. The library was screened for expression of MM specific antigens with a polyclonal antiserum that had been preadsorbed with antigens of the most common unrelated avian mycoplasma species. A 49-amino acid antigenic domain unique to MM was isolated, expressed in Escherichia coli, and its serodiagnostic potential was demonstrated. An antiserum raised against this MM-specific antigenic domain recognized a cluster of seven membrane-associated MM proteins with molecular masses ranging from 34 to 75 kDa. Overall, this study resulted in the identification of a potent serodiagnostic tool and revealed the complex antigenic nature of MM.

Pathogenicity of Mycoplasma meleagridis for Chicken Cells

Mycoplasma meleagridis (MM) is a known pathogen for turkeys only. In this study, MM was used to inoculate chicken embryos and tumor cells to assess its pathogenic potential for chickens. In chicken embryos, it caused abnormal-shaped toes and severely denuded tracheae. In chicken tumor cells, MM reduced the cellular capacity to release a chemoattractant that causes the migration of heterophils. MM also caused death and/or a reduced growth rate in chicken HD-11 cells, a macrophage-monocyte-derived cell line. Thus, the data show that MM is a potential pathogen for chicken embryos and chickens cells. Further exploration to determine the pathogenicity in chickens may be warranted.

Interactions between the membranes of turkey cells and Mycoplasma meleagridis

We used Myoplsma meleagridis (MM) to infect the RP-9 cells and the eggshell membranes and scanning electron microscopy (SEM) and confocal microscopy to study the interactions between the organisms and the cell surfaces. The surface of the RP-9 cells contained numerous projections. After 24 hr of infection with MM, those projections were either lost or aggregated to the side; MM-like particles could be seen on the surface of the cells, and surface fluorescence could be detected by confocal microscopy. On the surface of MM-infected shell membranes were necrotic fibrous tissues and cells detected by SEM and an intense surface fluorescence detected by confocal microscopy. These results indicate that MM infection of the cell surface can result in cellular damage.

Antigen heterogeneity and epitope variable expression in Mycoplasma meleagridis isolates

Immunoblotting was used to check the antigenic profiling of 27 Mycoplasma meleagridis strains isolated in different countries. Hyperimmune polyclonal rabbit antiserum as well as monoclonal antibodies (MAbs) raised against M. meleagridis (MM) showed antigen heterogeneity among strains. Five anti-MM MAbs were selected for lack of reaction against heterologous avian mycoplasma. Three of these five Mabs did not cross-react with 63 mycoplasma strains from six species affecting turkeys other than M. meleagridis. The five Mabs used to analyse the epitopes of 30 M. meleagridis strains indicated that some epitopes were not expressed in all strains. Moreover, other epitopes were located on proteins which differed according to number or molecular mass from strain to strain. The five Mabs therefore, recognised variable surface proteins, among which two were amphiphilic membrane proteins. Three of the selected Mabs recognised 29 or 30 of the 30 tested strains. The in vitro expression of surface epitopes in M. meleagridis ATCC 25284 was investigated by colony immunobinding and allowed demonstration of a variable antigenic system.

Detection of the turkey pathogens Mycoplasma meleagridis and M. iowae by amplification of genes coding for rRNA

PCR-based diagnostic tests using oligonucleotides specific to 16S rRNA were designed for the specific detection of the turkey pathogens Mycoplasma meleagridis and M. iowae. This method of detection was shown to be rapid, species specific, and unaffected by strain variation or the presence of other organisms. Detection of M. meleagridis in clinical samples by PCR was achieved and later confirmed by culture and growth inhibition. Definitive identification by culture and growth inhibition required up to 3 weeks, whereas positive results from PCR testing were obtained within a day and negative samples were confirmed within 4 days.

Detection of Mycoplasma meleagridis by polymerase chain reaction

A pair of 32 base primers was synthesized based on the DNA sequence data of a Mycoplasma meleagridis (MM) species-specific recombinant, pMM-2. The primers were used in a MM-polymerase chain reaction (PCR) to amplify a target DNA of approximately 850 bp. Annealing temperatures ranging from 58 degrees C to 61 degrees C could be used for the MM-PCR without loss of specificity. The primers amplified 1 ng of DNA from 17 strains of MM, but not 10 ng of DNA from 16 heterologous species of avian mycoplasma, pUC8 plasmid, lambda phage or calf thymus DNA. The minimum amount of target DNA detected by MM-PCR was 10 fg, which indicated that this procedure was 100000 times more sensitive than dot blot methodology using an MM recombinant DNA probe.

Species-specific recombinant DNA probes for Mycoplasma meleagridis

Two recombinant DNA probes (pMM-2 and pMM-13) were isolated from a Mycoplasma meleagridis strain 17529 genomic library prepared in plasmid pUC8, and Escherichia coli strain JM83. In dot blot assays, 32P-labeled pMM-13 with a DNA insert of 3.5 kbp, hybridized with 18 isolates of M. meleagridis but not with 16 other known species of avian mycoplasmas. Except for weaker signals on hybridization with the M. meleagridis cultures, pMM-2 with an DNA insert of 0.85 kbp, showed a similar reaction pattern. The minimal concentration of M. meleagridis strain 17529 chromosomal DNA that pMM-13 and pMM-2 detected were 1 and 8 ng, respectively. Neither probe hybridized with chromosomal DNA of M. gallisepticum strain S6, M. synoviae strain WVU-1853, or M. iowae strain I-695 at concentration of 256 ng.