Two cases of Mycoplasma gallisepticum infection in different avian species in backyard gamebird operations in Slovenia were investigated. In the first case, M gallisepticum was associated with severe respiratory disease with almost 20 per cent mortality in pheasants, whereas the infection was less pathogenic for chickens and turkeys reared at the same site. The M gallisepticum isolates from pheasants had a unique pMGA gene sequence containing a repeat of 12 nucleotides, and they contained only small amounts of the cytadhesins MGC1 and MGC3 and no PvpA protein. However, they expressed some typical M gallisepticum proteins and several proteins which were immunogenic for pheasants, chickens and turkeys. A strain of M gallisepticum isolated from the sinus of a pheasant was highly pathogenic for chicken embryos. In the second case, the M gallisepticum strain that was associated with respiratory disease and mortality in peafowl also affected chickens. M gallisepticum strain ULB 992 was isolated from the infraorbital sinus of a dead peafowl. The ULB 992 strain synthesised a small amount of MGC3, a truncated form of MGC1 and lacked PvpA. However, it expressed several proteins which were immunogenic for the birds infected with M gallisepticum at both gamebird operations.

SUMMARYChicken flocks hatched together but reared under different management systems were examined for mycoplasmas over a two-year period. On the farm A multiple-age flocks were reared in close contact. This farm had not been depopulated for over 15 years. On farms B, C and D single-age flocks were reared and the farms were depopulated every year. On farm A 218 birds from 20 flocks were tested: mycoplasmas were isolated from 202 (92.7%). On farms B, C and D 289 birds from seven flocks were tested: mycoplasmas were recovered from 55 (19.0%). On farm A the following mycoplasmas were identified: M. gallisepticum (46.9% of isolates), M. gallinarum (47.8%), M. pullorum (46.3%), M. gallinaceum (43.2%),M. iners (10.9%), M. iowae (8.3%),M. synoviae (51.7%), M. lipofaciens (23.8%) and M. glycophilum (16.7%). Furthermore, mycoplasma strains which do not belong to recognised species of avian mycoplasmas, Acholeplasma laidlawii and an unidentified Acholeplasma strain were also isolated. On farms B, C and D the isolates were identified as M. gallisepticum or M. synoviae. The only exception was one culture from which M. gallinarum was recovered. The differences between farm A and farms B, C and D regarding total mycoplasma isolation yields and incidence of their species are significant (/K0.01) and are attributed to the different management systems.

Within 1 mo, two separate outbreaks of respiratory disease occurred in two flocks on the multiage market turkey farm in Slovenia. More severe dinical signs and higher mortality were observed in male birds. Ornithobacterium rhinotracheale (ORT) was isolated in pure culture from tracheas of the affected birds in both outbreaks. Commercial enzyme-linked immunosorbent assay test showed the presence of antibodies to ORT in sera of birds from both clinically affected flocks and also in two flocks of younger birds without clinical sings. Immunoblotting with ORT culture isolated during the outbreak as an antigen confirmed the presence of antibodies to ORT in sera of turkeys of all four flocks examined. In addition, three different serologic assays also detected antibodies to Mycoplasma synoviae (MS) in three out of four flocks. The concomitant infection with MS did not show an obvious effect on mortality rates nor on the antibody response against ORT. Younger birds appeared to be less susceptible to ORT pathogenicity because in those flocks the infection was subclinical.

Chicken bile was examined for mycoplasma by culture and for antibody against mycoplasma by indirect immunoperoxidase assay (IIPA) detecting chicken either IgA or IgG and IgM, as well as by rapid plate agglutination (RPA), haemagglutination-inhibition (HI) and double immuno-diffusion (DID). Cultures indicated the presence of M. gallisepticum (Mg) and Ai. synoviae (Ms) in bile and their isolations were positively correlated with those from upper respiratory tract. In 45 chickens from five flocks examination of biliary samples with IIPA detected considerably higher rates of Mg and Ms antibodies than the same assay performed with sera especially those of IgA class of antibody. In chickens with a strong serological response to Mg, titres of specific agglutinins and HI antibody in biliary samples were significantly higher than those found in sera. Only biliary fractions containing Ig exhibited antibody activity.

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