NOVEL ANTIGENIC DETERMINANTS FROM PEPTIDORHAMNOMANNANS OF SPOROTHRIX-SCHENCKII

Antisera were raised in rabbits against acetone-dried yeast-like and m ycelium forms of Sporothrix schenckii. These antisera were tested for immunoprecipitation of peptido-rhamnomannans isolated from both cell t ypes. Both antisera reacted strongly with S.schenckii peptidorhamnoman nans, but the reactions were weak with beta-eliminated peptidopolysacc harides. These antisera did not recognize the Saccharomyces cerevisiae mannoprotein, and reacted poorly with Ceratocystis (Ophiostoma) steno ceras cell wall glycopeptides. Since beta-eliminated glycopeptides wer e poorly reactive, we investigated the activity of O-glycosidically li nked oligosaccharides which were liberated from the peptidorhamnomanna ns by mild alkaline hydrolysis, using a hapten inhibition test. The ra tes of inhibition showed that the immunodominant epitopes in O-linked tetra- and pentasaccharides had the following novel structures: alpha- L-Rhap (1-->4)-alpha-D-GlcpA and -L-Rhap(1-->4)-[alpha-L-Rhap(1-->2)]a lpha-D-GlcpA. Results suggest that peptidorhamnomannans or synthetic a ntigens bearing these epitopes should be used for the specific detecti on of anti-S.schenckii antibodies rather than the long-chain N-linked polysaccharides.