Abstract
When occurring together with the polysaccharide III-antigen the X-antigen displayed a phenotypic variation in vitro, and so did 1 R-strain. Genuine X-straims, and other types as well, seemed to remain unaffected by commonly used laboratory procedures. The hypothesis is advanced that previously described in-vivo variations of these antigens are induced by antibodies against the antigen in question.
Keywords: Group-B streptococci, serological types, variation of type antigens
Sammendrag
ulige årsager til de tidligere påviste variationer in vivo af gruppe B-streptokok (B-str.) typeantigener er undersøgt.
Det blev fundet:
At den anvendte typebestemmelsesmetode er følsom og specifik nok til at registrere kvantitative forskelle i B-str. stanumernes antigenoutput.
At kirtler fra starten kan være inficerede med to serotyper. Ved undersøgelse af 29 kirtler fandtes i 3 kirtler både Type III og Type IIIX, i 1 kirtel både Type II og NT (Tabel 1).
At laboratorieprocedurer kan medvirke ved typeskift (fasevariation).
Af 20 stammer – oprindelig typebestemt til III eller IIIX – varierede 14. Både Type III (4) og IIIX (2) var blandt de 6 konstante stammer. Polysakkarid III-antigenet var stabilt.
Fire NT-stammer, 4 X-stammer og 1 IIIR-stamme varierede ikke. En R-stamme varierede : R → NT. Polysakkaridantigenet II var stabilt in vitro (1 stamme).
Det konkluderes, at X-antigenet varierer tilfaeldigt når det optrseder i forbindelse med III-antigenet. Det synes derimod at være stabilt in vitro når det forekommer som eneste antigen. Andre undersøgte stammer (II, IHR, NT) var ligeledes stabile in vitro, men en R-stamme varierede.
På trods af variationerne kan X-antigenet have epidemiologisk betydning, da dette antigen, hvad danske B-str. stammer angår, næsten selektivt synes knyttet til det bovine reservoir.
Variationerne – in vivo og in vitro – nødvendiggør, at man ved epidemiologiske undersøgelser af bovin B-str. mastitis vurderer muligheden for sammenhaeng mellem forskellige „typer”, altså arbejder med besætningstypebegrebet.
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