Serologic Response to Cell Wall Mannoproteins and Proteins ofCandida albicans

Abstract

SUMMARY The cell wall of Candida albicans not only is the structure in which many biological functions essential for the fungal cells reside but also is a significant source of candidal antigens. The major cell wall components that elicit a response from the host immune system are proteins and glycoproteins, the latter being predominantly mannoproteins. Both the carbohydrate and protein moieties are able to trigger immune responses. Although cell-mediated immunity is often considered to be the most important line of defense against candidiasis, cell wall protein and glycoprotein components also elicit a potent humoral response from the host that may include some protective antibodies. Proteins and glycoproteins exposed at the most external layers of the wall structure are involved in several types of interactions of fungal cells with the exocellular environment. Thus, coating of fungal cells with host antibodies has the potential to influence profoundly the host-parasite interaction by affecting antibody-mediated functions such as opsonin-enhanced phagocytosis and blocking the binding activity of fungal adhesins for host ligands. In this review, the various members of the protein and glycoprotein fraction of the C. albicans cell wall that elicit an antibody response in vivo are examined. Although a number of proteins have been shown to stimulate an antibody response, for some of these species the response is not universal. On the other hand, some of the studies demonstrate that certain cell wall antigens and anti-cell wall antibodies may be the basis for developing specific and sensitive serologic tests for the diagnosis of candidasis, particularly the disseminated form. In addition, recent studies have focused on the potential for antibodies to cell wall protein determinants to protect the host against infection. Hence, a better understanding of the humoral response to cell wall antigens of C. albicans may provide the basis for the development of (i) effective procedures for the serodiagnosis of disseminated candidiasis and (ii) novel prophylactic (vaccination) and therapeutic strategies for the management of this type of infection.

Antimicrobial peptide protonectin disturbs the membrane integrity and induces ROS production in yeast cells

“…However, as we know, fungal cells have a polysaccharide cell wall as a boundary to protect them from the harsh environment. Accounting for 80-90% of the cell wall of Candida is constituted by carbohydrate that envelops cells with an elastic and multifunctional barrier and maintains structural integrity [22]. In Candida cells, glucan is a maximum in the cell wall, accounting for 60-65% of the total polysaccharides and mannan accounts for 20-25% [24].…”

“…As we know, fungal species has cell wall to protect the cell against harsh extracellular environment [22]. However, the role of fungal cell wall in the process of peptide-cell interaction is unintelligible.…”

Humoral and cell-mediated immunity following vaccination with synthetic Candida cell wall mannan derived heptamannoside–protein conjugate

“…The immunomodulation of fungal infections depends on the recognition of antigens that are able to induce proliferation and activation of effector cells of the immune system. Previous studies described that sequences of β-1,2-linked mannose residues located at the C. albicans cell surface may act as adhesins [1], induce generation of protective antibodies [2,3] and contribute to virulence [4,5]. The morphological change of Candida cells from the yeast form to the hyphal form induced a significant decrease in the phosphodiesterified acid-labile β-1,2-linked mannooligosaccharides [6].…”

Improved detection of Candida albicans with carbon nanotube field-effect transistors

“…In this way, we assume that once antiCandida antibodies interact with the antigen "mannan" present in the outer cell wall layer of C. albicans there is a charge transfer process. Mannans are molecules composed by homopolymers of d-mannose, which are linked to proteins by N-glycosidic bonds to asparagine residues and by O-glycosidic, alkali-labile linkages to threonine or serine residues [1]. Therefore, the charge transfer process could be mainly due to electron donating from the amino groups of the mannoproteins present in the cell wall of the yeast to the CNTs.…”

“…Candida albicans (C. albicans) is a yeast-like fungal organism that can make the morphologic transition from yeast to hyphal, thereby increasing its pathogenicity [1]. It can be found on human skin, in the digestive tract, mouth, throat, oesophagus, vagina and other mucus membranes causing a wide spectrum of diseases from simple cutaneous mycosis to complicated cases of candidiasis.…”