Hum mel, R., G . L e h man n : Bovine coagulase-negative Staphylococci: Biochemistry and Polymerase Chain Reaction. Acta vet. Brno, 63,1994: 133-139.Staphylococcus (S.) simulans, S. chromogenes, and S. epidermidis were the species of coagulase-negative staphylococci (CNS) most frequently involved in subclinical mastitits of dairy cattle. The same biochemical features characterized the successive isolates of a particular chronically infected udder quarter. Occurrence rate of the various species differed between the herds examined. In cases of clinical mastitis of cows S. xylosus, S. simulans, S. haemolyticus, and S. chromogenes predominated. A comparison between strains of the particular CNS species from infections in man and cattle did not show host attributable biochemical features or profiles obtained by polymerase chain reaction using arbitrary primers (AP-PCR). Materials and Methods Bacterial strainsThe CNS examined in this study originated from cases of clinical mastitis (54 strains) and of subclinical mastitits (57 strains) in cattle. For comparison, 8 strains from infections in man were included in these studies.Of the strains from bovine clinical mastitis 41 were isolated from udder secretions in 39 dairy herds submitted for bacteriological examination to the regional veterinary laboratory. An additional 13 strains originated from Belgium.The 57 strains from subclinical mastitis were selected in five large herds of cattle (Table 1) with 300 to 500 cows each. An infection of the mammary gland means isolation of CNS in pure culture together with an elevated total cell count (>300 000 cells/ml milk). Sampling of udder secretions was carried out before and after milking. Repeated isolates from a particular udder quarter possessed of the same biochemical features were considered a single strain. The 57 strains represented a total of 580 isolates. All of the herds practised post milking teat dipping but only two of them (herds Np and Lu) applied a proper hygiene at milking. There was an occasional history of Streptococcus agalacriae in these herds and the infected cows were removed for slaughter.In herd Np quarter milk samples from 463 cows at freshening were investigated for the presence of CNS infections. 21 cows with 29 chronically CNS infected quarters in herd Np were resampled monthly or bimonthly to the next freshening. The 29 strains represented a total of 502 isolates. In herds Mo and Zi, respectively, 7 out of 197 and 3 out of 293 cows could be found chronically infected. Three consecutive samplings were performed and a total of 42 isolates gathered. Herds Ka and Lu have been sampled only once.

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In accordance with the clonal selection theory we intended to prevent the development of artificially induced birch pollen allergy in rabbits with the aid of the radiolabelled pollen allergen (75-1000 microCi125 I-pollen/animal) intravenously administered prior to pollen sensitization. The birch pollen allergen, is accordance with Burnet's working hypothesis, reacts only with a genetically determining B cell subpopulation. The fixation of the radiolabelled birch pollen allergen to the receptors of the competent B cell clone causes the lesion of the latter. Compared with the control group, this group of rabbits showed an extensive suppression of anaphylactic reagin-like PCA-antibodies, and haemagglutinating antibodies in the blood as well as in nasal secretion. In addition, we tried to influence the already ongoing synthesis of the antibodies with the aid of subsequent intravenously administered radiolabelled birch pollen allergen (750-100 microCi 125 I-pollen/animal). An intensive suppression of the synthesis of antibodies could also be proved in this case. The simultaneous immunization of the control rabbits with birch pollen and egg albumin resulted in the production of antibodies against both antigens, as expected. The hot-labelled birch pollen antigen intravenously injected before or after immunization with egg albumin and birch pollen led selectively to suppression of anti-birch-pollen PCA antibodies. The synthesis of anti-egg albumin PCA antibodies was unaffected.

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