scholarly journals Antibody to Cryptococcus neoformans Glucuronoxylomannan Inhibits the Release of Capsular Antigen

2004 ◽  
Vol 72 (6) ◽  
pp. 3674-3679 ◽  
Author(s):  
Luis R. Martinez ◽  
Dariush Moussai ◽  
Arturo Casadevall
Keyword(s):  
Monoclonal Antibody ◽  
Cryptococcus Neoformans ◽  
Humoral Immunity ◽  
Capsular Polysaccharide ◽  
Liquid Cultures ◽  
Capsular Antigen

ABSTRACT Cryptococcus neoformans releases capsular polysaccharide in the supernatant of liquid cultures and in tissues. Significantly less glucuronoxylomannan (GXM) was released by C. neoformans in the presence of capsule-binding monoclonal antibody (MAb). MAb-mediated inhibition of GXM release may be another mechanism by which humoral immunity can mediate protection against this pathogen.

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.

scholarly journals Detection of Cryptococcus neoformans capsular polysaccharide antigen in asymptomatic HIV-infected patients

1995 ◽  
Vol 37 (5) ◽  
pp. 385-389 ◽  
Author(s):  
R. Negroni ◽  
C. Cendoya ◽  
A.I. Arechavala ◽  
A.M. Robles ◽  
M. Bianchi ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Capsular Polysaccharide ◽  
Detection System ◽  
Latex Agglutination ◽  
Antigen Detection ◽  
Hiv Positive ◽  
Cd4 Cells ◽  
Serum Samples ◽  
Capsular Antigen ◽  
Asymptomatic Hiv

Serum samples from 242 HIV-positive persons were studied for the detection of capsular polysaccha-ride antigen of Cryptococcus neoformans; 193 of these patients presented less than 300 CD4+ cells/µl of blood and 49 patients had more than 300 CD4+ cells/µl. None of them had symptoms or signs characteristic of cryptococcosis. The capsular antigen of C. neofarmans was detected by latex agglutination technique with pronase pre-treatment (IMMY, Crypto-Latex Antigen Detection System, Immunomycologics Inc., OK, USA); in 61% of the samples, ELISA technique was also used (Premier, Cryptococcal Antigen, Meridian Diagnostic Inc., Cincinatti, Oh, USA). The comparative study of both methods showed that the results obtained were similar in 96.9% of the cases. The capsular antigen was detected in 13 out of 193 (6.7%) patients with less than 300 CD4+ cells/µl. Cryptococcosis was confirmed mycologically in 3 of these 13 cases (23%) by the isolation of C. neoformans in CSF or blood cultures. Three patients, who had presented negative results of both tests for capsular antigen, suffered disseminated cryptococcosis 4 to 8 months later. The predictive diagnostic value of capsular antigen detection of C. neoformans seems tobe low and we believe that it should not be done routinely in asymptomatic HIV-positive persons.

scholarly journals Antibodies Produced in Response to Cryptococcus neoformans Pulmonary Infection in Mice Have Characteristics of Nonprotective Antibodies

2004 ◽  
Vol 72 (7) ◽  
pp. 4271-4274 ◽  
Author(s):  
Oscar Zaragoza ◽  
Arturo Casadevall
Keyword(s):  
Cryptococcus Neoformans ◽  
Humoral Immunity ◽  
Pulmonary Infection ◽  
Capsular Polysaccharide ◽  
Immunoglobulin M ◽  
Antibody Responses ◽  
Yeast Cells ◽  
Serum Immunoglobulin

ABSTRACT Murine cryptocococcal pulmonary infection elicited serum immunoglobulin M (IgM) and IgG to the capsular polysaccharide, but only IgG stained yeast cells in alveoli. Both isotypes produced punctuate immunofluorescence patterns on yeast cells like those of nonprotective antibodies. The difficulties involved in associating humoral immunity with protection in murine cryptocococcal infection could reflect nonprotective antibody responses.

scholarly journals Antibody-Mediated Immobilization of Cryptococcus neoformans Promotes Biofilm Formation

2009 ◽  
Vol 75 (8) ◽  
pp. 2528-2533 ◽  
Author(s):  
Emma J. Robertson ◽  
Arturo Casadevall
Keyword(s):  
Monoclonal Antibody ◽  
Cryptococcus Neoformans ◽  
Biofilm Formation ◽  
Capsular Polysaccharide ◽  
Time Lapse ◽  
Biofilm Growth ◽  
Time Lapse Microscopy ◽  
Antibody Capture ◽  
Pathogenic Microbes ◽  
Antibody Coating

ABSTRACT Most microbes, including the fungal pathogen Cryptococcus neoformans, can grow as biofilms. Biofilms confer upon microbes a range of characteristics, including an ability to colonize materials such as shunts and catheters and increased resistance to antibiotics. Here, we provide evidence that coating surfaces with a monoclonal antibody to glucuronoxylomannan, the major component of the fungal capsular polysaccharide, immobilizes cryptococcal cells to a surface support and, subsequently, promotes biofilm formation. We used time-lapse microscopy to visualize the growth of cryptococcal biofilms, generating the first movies of fungal biofilm growth. We show that when fungal cells are immobilized using surface-attached specific antibody to the capsule, the initial stages of biofilm formation are significantly faster than those on surfaces with no antibody coating or surfaces coated with unspecific monoclonal antibody. Time-lapse microscopy revealed that biofilm growth was a dynamic process in which cells shuffled position during budding and was accompanied by emergence of planktonic variant cells that left the attached biofilm community. The planktonic variant cells exhibited mobility, presumably by Brownian motion. Our results indicate that microbial immobilization by antibody capture hastens biofilm formation and suggest that antibody coating of medical devices with immunoglobulins must exclude binding to common pathogenic microbes and the possibility that this effect could be exploited in industrial microbiology.

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