Protein and antigen variability among strains of Mycoplasma arthritidis

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.

Identification of novel species-specific antigens of Mycoplasma hyopneumoniae by preparative SDS-PAGE ELISA profiling

Mycoplasma hyopneumoniae, M. hyorhinis and M. flocculare are commonly isolated from the respiratory tract of pigs and are phylogenetically related. The identification and characterization of antigens specific for M. hyopneumoniae is crucial for the development of serological reagents and for understanding the mechanisms of pathogenicity of this pathogen. Protein and antigen profiles of six strains of M. hyopneumoniae, four strains of M. hyorhinis and a type strain of M. flocculare were compared using SDS-PAGE and immunoblotting. Five strains of M. hyopneumoniae originally isolated from diverse geographical regions produced similar protein and antigen profiles. One strain, C1735/2, produced a unique protein profile and was poorly immunoreactive, suggesting that some strains of M. hyopneumoniae may possess a structurally modified repertoire of antigens. Major M. hyopneumoniae antigens with molecular masses of approximately 36, 43, 48, 52, 76, 78, 80, 82, 94, 106, 114 and 200 kDa were identified by immunoblotting using hyperimmune pig sera raised against both high and low passage strains of M. hyopneumoniae. Porcine hyperimmune sera raised against the GDL type strain of M. hyorhinis reacted strongly with all M. hyorhinis strains although the profiles displayed considerable variation. Major antigens of molecular mass 42, 49, 52, 78, 80 and 82 kDa were identified in type strains GDL and BTS-7 and field strain 2; however, field strain 1 produced a unique profile. A preparative SDS-PAGE profiling (PPP) technique was developed which enabled quantification of the immunoreactivity of denatured antigens with porcine serum by ELISA. PPP facilitated the rapid identification of species-specific and cross-reactive antigens among the three mycoplasma species. PPP studies revealed several strongly immunoreactive M. hyopneumoniae-specific antigens of 43, 76, 94, 114 and 200 kDa as well as antigens of molecular mass between 52 and 62 kDa which were not apparent in immunoblotting studies. Rabbit monospecific anti-42 kDa serum reacted specifically with a 43 kDa antigen in whole cell lysates of geographically diverse strains of M. hyopneumoniae and failed to cross-react with M. flocculare or M. hyorhinis whole cell lysates. This study has identified a number of M. hyopneumoniae-specific antigens which warrant further investigation to determine their potential as diagnostic reagents and the role they play, if any, in pathogenicity.

Comparison of Mycoplasma arthritidis strains by enzyme-linked immunosorbent assay, immunoblotting, and DNA restriction analysis

Twenty Mycoplasma arthritidis strains or isolates were compared by a combination of enzyme-linked immunosorbent assay by an antiserum adsorption technique, Western immunoblotting, and restriction analysis of chromosomal DNA. Antigenic markers that defined strains related to strains 158p10p9, PG6, and H606 were identified. In addition, restriction analysis allowed all 20 strains to be divided into six groups. Results of restriction analysis corresponded generally with antigenic similarities, although the former did not allow grouping with as fine a precision as the latter. However, intrastrain antigenic variability, which is common among many Mycoplasma species, including M. arthritidis, introduced a complicating factor into our attempts at antigenic analysis. While serologic and antigenic analyses remain useful, we recommend that they be used with caution and in combination with other techniques for identifying and characterizing new isolates and newly acquired strains. Combinations of these techniques have proven to be useful in our laboratory for quality control and for uncovering interesting relationships among strains subjected to animal passage and their less virulent antecedents and among strains originally classified as the same but obtained from different sources and maintained, sometimes for decades, in different laboratories.

Polypeptide cartography of Spiroplasma taiwanense

Spiroplasma taiwanense is the first member of the Class Mollicutes to be subjected to polypeptide cartography using computerized image analysis. The small genome size characteristic of this group was shown to code for low numbers of polypeptides when compared to other bacterial species. Silver-stained two-dimensional electrophoresis gels, following separation by either isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (ISO-DALT) or nonequilibrium pH gradient electrophoresis (NEPHGE), were used to create databases from 10 and 6 gels, respectively, for each technique and produced, respectively, 263 and 287 replicated spots. Polypeptides were mapped with respect to molecular mass and glyceraldehyde-3-phosphate dehydrogenase carbamylation standards. Of interest was the unexpectedly high percentage (50.2%) of the total normalised optical intensity associated with all 263 spots detected by ISO-DALT electrophoresis, having been contributed by just 29 dominant protein spots. These 29 polypeptides are to be given priority in microsequencing and microanalysis aimed at their identification.