Abstract
This project was undertaken because of the lack of published work comparing the serological and biochemical properties of porcine mycoplasmas. Seven strains of M. hyorhinis were isolated from swine lungs and were compared with a number of strains of M. suipneumoniae, M. hyorhinis, M. hyosynoviae and A. granularum by growth inhibition, complement fixation, metabolic inhibition and flat gel polyacrylamide electrophoresis. The analysis of porcine mycoplasmas by flat gel polyacrylamide electrophoresis showed that whilst the technique is useful for species identification, it is not sufficiently sensitive to differentiate between strains of M. hyorhinis and M. hyosynoviae at the sub-species level. However, the flat gel polyacrylamide electrophoresis system has the advantage that different protein samples can be examined in parallel without the rearrangement of separate gel columns required with the tube technique. The growth inhibition test was found to be species---specific, and the well method was found to be more sensitive than the disc technique for comparing strains of M. hyorhinis and for studying M. suipneumoniae. There was a degree of heterogeneity in the growth inhibition results with M. hyorhinis which suggested that there were antigenic differences between the 12 M. hyorhinis strains examined. Complement fixation and metabolic inhibition tests were found to be useful for examining M. hyorhinis at the sub-species level although some cross-reactions were noted between species using complement fixation. Differences were noted between strains of M. hyosynoviae using complement fixation, although the differences within M. hyorhinis and M. hyosynoviae were not sufficient for the species to be subdivided. Although the techniques used in this study have shown that the 20 porcine mycoplasmas can be grouped into species, the different tests have not shown agreement in differentiating between the 12 strains of M. hyorhinist and it is suggested that different antibodies are involved in the growth inhibition and metabolic inhibition tests.