title: Galactoxylomannans from Cryptococcus neoformans varieties neoformans and grubii are structurally and antigenically variable.
abstract: Prior studies have established that the Cryptococcus neoformans capsular polysaccharide component galactoxylomannan (GalXM) manifests serotype-related structural differences that translate into antigenic differences. We analyzed GalXM from acapsular serotype A and D strains by carbohydrate analysis and static and dynamic light scattering to determine mass, effective diameter, polydispersity, and diffusion coefficients. Multiangle laser light scattering showed that GalXM from C. neoformans var. grubii strain cap59 (serotype A) had larger molecular mass (4.21 x 10(6) +/- 0.95 x 10(6) g/mol) and radius of gyration (207 +/- 27 nm) than GalXM from C. neoformans var. neoformans cap67 (serotype D). cap67 GalXM had corresponding values of 0.70 x 10(6) +/- 0.05 x 10(6) g/mol and 120 +/- 22 nm, respectively. The effective diameter for GalXM and polydispersity from the two strains varied depending on temperature and medium growth conditions, indicating that GalXM structure can vary within a strain, depending on its environment. Zeta potential determinations were negative for GalXM from both strains under all conditions, consistent with the recently reported presence of glucuronic acid. These results imply that C. neoformans GalXM, like glucuronoxylomannan, can manifest variety- and growth condition-related variations. Analysis of 16 C. neoformans and 7 Cryptococcus gattii strains with polyclonal antibody to a GalXM strain revealed antigenic similarities among the C. neoformans variety neoformans and grubii strains and no reactivity with C. gattii. As a result of the deleterious effects of GalXM on immune function, structural and antigenic variability between serotypes may translate into differences in immunomodulatory effects.
authors.affiliation: Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA.
authors.forename: Magdia
authors.initials: M
authors.lastname: De Jesus
authors.forename: Siu-Kei
authors.initials: SK
authors.lastname: Chow
authors.forename: Radames J B
authors.initials: RJ
authors.lastname: Cordero
authors.forename: Susana
authors.initials: S
authors.lastname: Frases
authors.forename: Arturo
authors.initials: A
authors.lastname: Casadevall
mesh_terms: D000908:Antibodies, Fungal / Q000276:immunology; D000946:Antigens, Fungal / Q000276:immunology*; D003455:Cryptococcus neoformans / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000276:immunology*; D003470:Culture Media / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D008027:Light; D008970:Molecular Weight; D011134:Polysaccharides; D011135:Polysaccharides, Bacterial / Q000737:chemistry* / Q000276:immunology*; D012542:Scattering, Radiation; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature
chemical_list: D000908:Antibodies, Fungal; D000946:Antigens, Fungal; D003470:Culture Media; D011134:Polysaccharides; D011135:Polysaccharides, Bacterial; D012965:Sodium Chloride; C043689:galactoxylomannan