Studies on some bovine mycoplasmas

My studies on bovine mycoplasnas fall under three separate headings:A. ANGPLASMA MYQPI.DES VAR. MCOIDES AND CONTÁ2IOUS BOVINE UROPNEUMONIA. An investigation was undertaken to determine whether the allergic reaction could be developed as a useful diagnostic test for contagious bovine pleuropneumonia. Using antigens obtained from M. mycoides var. n coides two types of reaction were observed, an immediate reaction associated with lipopolysaccharide material and a delayed reaction associated with protein. It was impossible to separate the protein completely from the lipopolysaccharide, which elicited some non-specific reactions, and the test was abandoned.A comparison of various serological tests employed in contagious bovine pleuropneumonia diagnosis revealed that no single test was entirely satisfactory, but the complement fixation test was the best available. Growth inhibition of M. mycoides var. mycoides by serum was examined as a diagnostic test and as a measure of immunity. Two tests were evolved, one on solid medium and the other in liquid medium, and both proved to be of potential value for contagious bovine pleuropneumonia diagnosis, but their value in measuring immunity was not determined. Inhibition was observed, to occur in the absence of agglutination and heat-labile accessory factors.The lipopolysaccharide from M. mycoides var. mycoides, responsible for the immediate allergic reaction, was shown to be serologically related to a galactan extracted from normal bovine lung. This lipopolysaccharide was also shown to be aritigenically related to polysaccharides from a number of different sources including other microorganisms and this relationship was considered to be responsible for non-specific reactions discerned in diagnostic tests.It was suggested that the serological relationship between the lipopolysaccharide of M. Ayssides vay_t_mycoides and the galactan from bovine lung might play a role in the pathogenesis of contagious bovine pleuropneumonia. A preliminary examination of this percept was inconclusive, but it was shown, fortuitously, that immunity could be transferred passively.Electronmicroscopic examination of ItmmixleamaEl. ycoides, treated with specific antiserum, revealed a capsule or slime layer round the organisms. This capsule is probably composed of galactan.A method devised for the production, testing and transport of a modified Ti contagious bovine pleuropneumonia vaccine is described.Chicken embryos, from hens previously inoculated with M. mycoides var. mycoides, were immune to challenge with this organism, suggesting that the chicken embryo might be a suitable host for studying immunity to contagious bovine pleuropneumonia.B. MYCOPLASMAS WITH CALF NEUMONIA AND BOVINE KERATOCON'UNCTIVITIS. Material from pneumonic lungs cultured in special media resulted in the isolation of two species of xaycoplasma hitherto unrecorded from lungs. One was a new species of mycoplasma, subsequently named M. dispar, and the other was T-mycoplasna. Mycoplasmas were isolated from 75% of 65 pneumonic lungs examined; these comprised T-mycoplasmas from 58.5% of lungs, M. dispar from 51% and M. bovirhinis from 23%.The pathogenicity of the T-mycoplasmas was tested by inoculating cultures endobronchially into 3-week-old calves. Gross pneumonic lesions were observed in 14 out of the 16 calves at slaughter, compared with 2 out of 9 that revealed lesions following inoculation of control materials (P