Cherniak R, Valafar H, Morris LC, Valafar F; American Society for Microbiology. General Meeting.

Abstr Gen Meet Am Soc Microbiol. 1997 May 4-8; 97: 266 (abstract no. F39).

Georgia State University, Atlanta, GA.

The disposition of the O-acetyl substituents contributes to the antigenic multiplicity observed in GXMs obtained from all serotypes (A, B, C, D and A/D). Generally the serological activity observed with type specific antibodies is lost after O-deacetylation. The O-acetyl may be part of the epitope; it may serve to fix the conformation of the epitope; or it may serve in both capacities. Consequently, the relationship of the variation in GXM structure cannot be correlated to the range of virulence observed among C. neoformans isolates using serological reagents. HNMR spectroscopy is used to determine the structure of GXMs; composition and primary sequence. Seven structural motifs based on a alpha-(1-3)-mannotriose substituted with variable quantities of 2-O-beta/4-O-beta-Xyl and 2-O-beta-G1cA have been identified; MO through M6 triad repeating units. Chemical shifts of the anomeric protons of the mannosyl residues serve as reporter groups for the identification and quantitation of the triads present in any GXM. A learning set of 60 GXMs for which NMR and structural data were determined (Felix 95 and PeakFit) was used to train a neural network. The quantitative distribution of the triads was determined by the neural network for 40 NMR data sets not used for training. The results were compared to the quantitative distribution of structural triads of the 40 GXMs determined by Felix 95 and PeakFit. Serotype A isolate 150 has 45% M2 and 55% M3 by PeakFit and 41% M2 and 62% M3 by the neural network. Serotype D 9375 has 74% M1, 16% M5 and 10% M6 by PeakFit and has 71% M1, 12% M5 and 10% M6 by the neural network. Similar comparisons were made for the other GXMs of the test set. Rapid identification and quantitation of triads present in an isolate is done by the online submission of the 1 D proton data of the reporter group region of the spectrum to the neural network.

Publication Types:

• Meeting Abstracts

Keywords:

• Antigens, Fungal
• Computer Simulation
• Computers
• Cryptococcus neoformans
• Epitopes
• Indicators and Reagents
• Magnetic Resonance Spectroscopy
• Molecular Conformation
• Polysaccharides
• glucuronoxylomannan
• immunology

Other ID:

• 98928690

UI: 102235343

From Meeting Abstracts