scholarly journals Studies on Fungal Polysaccharides. III. Chemical Structure of the Capsular Polysaccharide from Cryptococcus neoformans.

1961 ◽  
Vol 9 (10) ◽  
pp. 829-833 ◽  
Author(s):  
Toshio Miyazaki
Keyword(s):  
Cryptococcus Neoformans ◽  
Chemical Structure ◽  
Capsular Polysaccharide ◽  
Fungal Polysaccharides

scholarly journals The capsule ofCryptococcus neoformansmodulates phagosomal pH through its acid-base properties

2018 ◽  
Author(s):  
Carlos M. De Leon-Rodriguez ◽  
Man Shun Fu ◽  
M. Osman Corbali ◽  
Radames J.B. Cordero ◽  
Arturo Casadevall
Keyword(s):  
Cryptococcus Neoformans ◽  
Capsular Polysaccharide ◽  
Glucuronic Acid ◽  
Pathogenic Fungus ◽  
Weak Acid ◽  
Phagocytic Cells ◽  
Acid Base ◽  
Encapsulated Cells ◽  
Human Pathogenic Fungus ◽  
Base Properties

AbstractPhagosomal acidification is a critical cellular mechanism for the inhibition and killing of ingested microbes by phagocytic cells. The acidic environment activates microbicidal proteins and creates an unfavorable environment for the growth of many microbes. Consequently, numerous pathogenic microbes have developed strategies for countering phagosomal acidification through various mechanisms that include interference with phagosome maturation. The human pathogenic fungusCryptococcus neoformansresides in acidic phagosome after macrophage ingestion that actually provides a favorable environment for replication since the fungus replicates faster at acidic pH. We hypothesized that the glucuronic acid residues in the capsular polysaccharide had the capacity to affect phagosome acidity through their acid-base properties. A ratiometric fluorescence comparison of imaged phagosomes containingC. neoformansto those containing beads showed that the latter were significantly more acidic. Similarly, phagosomes containing non-encapsulatedC. neoformanscells were more acidic than those containing encapsulated cells. Acid-base titrations of isolatedC. neoformanspolysaccharide revealed that it behaves as a weak acid with maximal buffering capacity around pH 4-5. We interpret these results as indicating that the glucuronic acid residues in theC. neoformanscapsular polysaccharide can buffer phagosomal acidification. Interference with phagosomal acidification represents a new function for the cryptococcal capsule in virulence and suggests the importance of considering the acid-base properties of microbial capsules in the host-microbe interaction for other microbes with charged residues in their capsules.ImportanceCryptococcus neoformansis the causative agent of cryptococcosis, a devastating fungal disease that affects thousands of individuals worldwide. This fungus has the capacity to survive inside phagocytic cells, which contributes to persistence of infection and dissemination. One of the major mechanisms of host phagocytes is to acidify the phagosomal compartment after ingestion of microbes. This study shows that the capsule ofC. neoformanscan interfere with full phagosomal acidification by serving as a buffer.

UDP Glucuronate Decarboxylase and Synthesis of Capsular Polysaccharide in Cryptococcus neoformans

1982 ◽  
Vol 152 (2) ◽  
pp. 932-934
Author(s):  
Eric S. Jacobson ◽  
William R. Payne
Keyword(s):  
Cryptococcus Neoformans ◽  
Capsular Polysaccharide ◽  
Decarboxylase Activity

UDP glucuronate decarboxylase activity was comparable in encapsulated and non-encapsulated strains of Cryptococcus neoformans , required NAD ( K a = 0.2 mM), and was inhibited by NADH ( K i = 0.1 mM) and UDP xylose.

scholarly journals Monoclonal Antibodies Reactive with Immunorecessive Epitopes of Glucuronoxylomannan, the Major Capsular Polysaccharide of Cryptococcus neoformans

2003 ◽  
Vol 10 (5) ◽  
pp. 903-909 ◽  
Author(s):  
Suzanne Brandt ◽  
Peter Thorkildson ◽  
Thomas R. Kozel
Keyword(s):  
Monoclonal Antibody ◽  
Immune Response ◽  
Monoclonal Antibodies ◽  
Cryptococcus Neoformans ◽  
Capsular Polysaccharide ◽  
Passive Immunization ◽  
The Other ◽  
Serotype A ◽  
Humoral Immune ◽  
New Information

ABSTRACT Cryptococcus neoformans is surrounded by an antiphagocytic capsule whose primary constituent is glucuronoxylomannan (GXM). An epitope shared by GXM serotypes A, B, C, and D is immunodominant when mice are immunized with serotype A GXM. In contrast, an epitope shared only by serotypes A and D is immunodominant when mice are immunized with serotype D. Hybridomas secreting antibodies reactive with subdominant epitopes were identified through a positive-negative screening procedure in which antibody-secreting colonies were characterized by reactivity with both the immunizing polysaccharide and GXMs from each of the four major serotypes. In this manner, a monoclonal antibody (MAb) that was reactive with an epitope shared only by serotypes A and B was identified and designated F10F5. Such an epitope has not been described previously. Immunization of mice with de-O-acetylated serotype A GXM generated a hybridoma that secreted an antibody, designated F12D2, that was reactive with all four serotypes. Unlike previously described monoclonal and polyclonal panspecific antibodies, the reactivity of MAb F12D2 was not altered by de-O-acetylation of GXM. These results indicate that there are at least two panspecific GXM epitopes; one epitope is dependent on O acetylation for antibody reactivity, and the other is independent of O acetylation. This study identifies strategies for production of MAbs that are reactive with subdominant or cryptic GXM epitopes and provides new information regarding the antigenic makeup and the humoral immune response to GXM, an essential virulence factor that is a target for active and passive immunization.

SPECIFIC DEGRADATION OF CRYPTOCOCCUS NEOFORMANS 3723 CAPSULAR POLYSACCHARIDE BY A MICROBIAL ENZYME: I. ISOLATION, PARTIAL PURIFICATION, AND PROPERTIES OF THE ENZYME

1961 ◽  
Vol 7 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Hans H. Gadebusch ◽  
John D. Johnson
Keyword(s):  
Cryptococcus Neoformans ◽  
Capsular Polysaccharide ◽  
Enzyme Reaction ◽  
Partial Purification ◽  
Intracellular Enzyme ◽  
Purification And Properties ◽  
Microbial Enzyme ◽  
Specific Degradation ◽  
Kinetics Of ◽  
Enzyme I

A partially purified intracellular enzyme from a species of Alcaligenes is described which specifically initiates the degradation of the he heteropolysaccharide of Cryptococcus neoformans, isolate 3723, The enzyme is active in the presence of serum and can be inactivated by heating at 45 °C for 10 minutes, The kinetics of the enzyme reaction are similar to those of other enzymes. Recovery and identification of the four known monosaccharides from enzymatic hydrolyzates suggest the presence of a number of other enzymes in these preparations.

scholarly journals Immunoglobulin G3 blocking antibodies to the fungal pathogen Cryptococcus neoformans.

1996 ◽  
Vol 183 (4) ◽  
pp. 1905-1909 ◽  
Author(s):  
G Nussbaum ◽  
R Yuan ◽  
A Casadevall ◽  
M D Scharff
Keyword(s):  
Cryptococcus Neoformans ◽  
Host Defense ◽  
Fungal Pathogen ◽  
Capsular Polysaccharide ◽  
Protective Efficacy ◽  
Antibody Therapy ◽  
Antibody Isotype ◽  
Cryptococcal Infection ◽  
Epitope Specificity ◽  
Blocking Antibodies

Vaccination and infection can elicit protective and nonprotective antibodies to the fungus Cryptococcus neoformans in mice. The effect of nonprotective antibodies on host defense is unknown. In this study we used mixtures of protective and nonprotective monoclonal antibodies (mAbs) to determine if nonprotective mAbs blocked the activity of the protective mAbs. Antibody isotype and epitope specificity are important in determining the ability to prolong survival in mice given a lethal C. neoformans infection. Three different nonprotective immunoglobulin (Ig) G23 mAbs to cryptococcal capsular polysaccharide were used to study the interaction between the IgG3 isotype and protective IgG1 and IgG2a mAbs in murine cryptococcal infection. One IgG3 mAb reduced the protective efficacy of an IgG1 with identical epitope specificity. A second IgG3 mAb with different epitope specificity also reduced the protection provided by the IgG1 mAb. The protective efficacy of an IgG2a mAb was also dramatically decreased by still another IgG3 mAb. To our knowledge this is the first report of blocking antibodies to a fungal pathogen. The results have important implications for the development of vaccines and passive antibody therapy against C. neoformans.

scholarly journals Immunochemical Properties of the Staphylococcal Poly-N-Acetylglucosamine Surface Polysaccharide

2002 ◽  
Vol 70 (8) ◽  
pp. 4433-4440 ◽  
Author(s):  
Tomás Maira-Litrán ◽  
Andrea Kropec ◽  
C. Abeygunawardana ◽  
Joseph Joyce ◽  
George Mark ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Staphylococcus Epidermidis ◽  
Chemical Structure ◽  
Capsular Polysaccharide ◽  
Analytical Techniques ◽  
Molecular Size ◽  
Wide Range ◽  
Molecular Masses ◽  
Surface Polysaccharide ◽  
Average Molecular Masses

ABSTRACT Staphylococcus aureus and Staphylococcus epidermidis often elaborate adherent biofilms, which contain the capsular polysaccharide-adhesin (PS/A) that mediates the initial cell adherence to biomaterials. Biofilm cells produce another antigen, termed polysaccharide intercellular adhesin (PIA), which is composed of a ∼28 kDa soluble linear β(1-6)-linked N-acetylglucosamine. We developed a new method to purify PS/A from S. aureus MN8m, a strain hyperproducing PS/A. Using multiple analytical techniques, we determined that the chemical structure of PS/A is also β(1-6)-N-acetylglucosamine (PNAG). We were unable to find N-succinylglucosamine residues in any of our preparations in contrast to previously reported findings (D. McKenney, K. Pouliot, Y. Wang, V. Murthy, M. Ulrich, G. Doring, J. C. Lee, D. A Goldmann, and G. B. Pier, Science 284:1523-1527, 1999). PNAG was produced with a wide range of molecular masses that could be divided into three major fractions with average molecular masses of 460 kDa (PNAG-I), 100 kDa (PNAG-II), and 21 kDa (PNAG-III). The purified antigens were not soluble at neutral pH unless first dissolved in 5 M HCl and then neutralized with 5 M NaOH. PNAG-I was very immunogenic in rabbits, but the responses of individual animals were variable. Immunization of mice with various doses (100, 50, or 10 μg) of PNAG-I, -II, and -III demonstrated that only PNAG-I was able to elicit an immunoglobulin G (IgG) immune response with the highest titers obtained with 100-μg dose. When we purified a small fraction of PNAG with a molecular mass of ∼780 kDa (PNAG-780) from PNAG-I, significantly higher IgG titers than those in mice immunized with the same doses of PNAG-I were obtained, suggesting the importance of the molecular mass of PNAG in the antibody response. These results further clarify the chemical structure of PS/A and help to differentiate it from PIA on the basis of immunogenicity, molecular size, and solubility.

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