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The further attenuated Enders (FAE) measles vaccine strain and the Edmonston B-Zagreb (EZ) measles vaccine strain were compared. In VERO-cells plaque sizes of FAE varied between 0.5 and 1 mm, those of EZ between 1 and 2 mm in diameter. The lots available in Switzerland during a 2 year period showed virus titers of 10(3.1) to 10(4.0) TCID50 per dose in the one vaccine (FAE) and of 10(3.1) to 10(4.5) TCID50 per dose in the other (EZ). Clinical investigations were performed with FAE and EZ monovalent and trivalent (measles + mumps + rubella) vaccine preparations. The virus titers of the vaccine lots used were 10(3.1) to 10(4.0) TCID50 per dose. The overall seroconversion rates of 96% to 100% indicate that both types of vaccine have comparable immunization properties. Stability tests demonstrated good stability of both the FAE and the EZ vaccines. Thus conservation at 37 degrees C was possible for 2 and 4 weeks, respectively, and at 41 degrees C for 6 and 6 days, respectively, without undue loss of live virus content (less than 1 log 10). Since the EZ vaccine is derived from human diploid cells, it is particularly suitable for the vaccination of persons with a history of allergy to avian proteins.

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An enzyme-linked immunosorbent assay (ELISA) was proposed as an alternative to the complement-fixation test (CF) for the detection of antibodies of Haemophilus pleuropneumoniae, agent of the pleuropneumonia in pigs. In tests done with different antigen-extraction procedures (including Tween 20, sodium dodecyl sulfate, aqueous phenol, sonification, and heat treatment at 120 C), ethylenediaminetetraacetic acid (EDTA) provided a satisfactorily reactive antigen. Chromatography purification on Sephacryl S200 improved the specificity of this antigen. Using hyperimmune rabbit sera, we investigated the specificity and the sensitivity of the ELISA with the EDTA-purified antigen of the different serotypes of H pleuropneumoniae on selected swine sera in herds with confirmed H pleuropneumoniae infection, from specific-pathogen-free animals showing doubtful CF reactions. The ELISA proved to be highly specific and more sensitive than the CF test. Furthermore, evidence of cross-reactions with H parasuis, a common bacteria isolated in swine populations, was not found.

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Litters of pigs were vaccinated with inactivated Mycoplasma hyopneumoniae organisms in Freund's complete adjuvant. The cell-mediated and humoral immune response following vaccination was investigated, and the protective effect of the induced immunity was assayed. The cell-mediated immune response to whole M hyopneumoniae organisms was determined as incorporation of tritiated thymidine, using a microculture system. After vaccination, detectable sensitization of peripheral blood lymphocytes was induced. The inoculations induced considerable antibody titers in the animals. The animals were challenged exposed by natural infection and protective effect of the cell-mediated or humoral response could not be detected.

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The preparation of an antigen of Mycoplasma hyopneumoniae containing selected proteins after treatment with the neutral detergent Tween 20 and purification on Sephadex G25 is described. The antigenic activity and the specificity were determined by means of an enzyme linked immunosorbent assay and compared with that of a whole-cell, SDS-solubilised antigen. The Tween 20 purified antigen showed a comparable activity but a higher specificity.

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Several Mycoplasma and Acholeplasma species chosen at random and solubilized with sodium dodecyl sulphate showed a common periodic acid-Schiff positive band with an apparent molecular weight of about 64 000, when examined by polyacrylamide gel electrophoresis. Another more cathodic minor band was detected in M. hyopneumoniae and M. flocculare. The common periodic acid-Schiff positive band appeared when a precipitate of serum constituents of the uninoculated growth medium after incubation was examined. The minor band was identified as a serum glycoprotein contaminating mycoplasmas grown in the presence of swine serum. We draw attention to the compounds as a possible source of error in serological tests or in the lymphocyte stimulation response. After lithium diiodosalicylate solubilization and aqueous phenol extraction, polyacrylamide gel electrophoresis showed a periodic acid-Schiff positive band in membranes from M. hyopneumoniae (molecular weight 75 000) and M. hyorhinis (molecular weight 80 000), suggesting the presence of a membrane glycoprotein. Such a glycoprotein was absent from A. granularum. Since the common periodic acid-Schiff positive band was not extracted by aqueous phenol, this growth medium constituent did not contaminate the preparations of membrane glycoproteins. However, the minor band was present in glycoprotein preparations of M. hyopneumoniae grown in the presence of swine serum.

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