The cell wall of fungal human pathogens: Its possible role in host-parasite relationshipsA review

TLDR: The pathogenic fungi included in this review are classified according to their cell wall structure, following Bartnicki-Garcia's criteria (15) on the distribution of the two major polysaccharides within the fungal cell wall.

Abstract: The ability of some fungi to cause disease in animals, and particularly in humans, appears to be related to some peculiar trait of their metabolism not shared by taxonomically related species, so that among thousands of species of fungi, only some 100 are considered pathogenic for humans. Recently, there has been an increase in the basic research aimed at elucidating the physiology, biochemistry, and mechanisms of pathogenicity of the fungi in addition to the responses of the infected host. The results from these studies are often difficult to compare because of the lack of reference cultures, and because variability among laboratories are found for many parameters such as origin of isolates, growth conditions, and fractionation procedures used to obtain chemically defined components of cell walls. This review deals with cell wall structures and their influence in host-parasite relationships in those relatively few pathogenic fungi on which substantial literature exists. Serological properties of the walls are included when available. Readers interested in medical and biological aspects of fungi may consult Rippon's (140) and Emmons et al.'s (51) textbooks, among others. Some reviews on microbial surfaces and their relationships to pathogenicity have been published (160 162)2 The pathogenic fungi included in this review are classified according to their cell wall structure, following Bartnicki-Garcia's criteria (15) on the distribution of the two major polysaccharides within the fungal cell wall. This classification is based on the fact that fungi may be subdivided into various categories according to the chemical nature of their walls, and that these categories closely parallel conventional taxonomic boundaries. As seen in Table l, this classification is based on dual combinations of those polysaccharides which appear to be the principal component of vegetative walls, disregarding the presence of small amounts of other classifying polysaccharides. The few pathogenic fungi whose cell walls have been studied to some extent belong to Bartnicki-Garcia's categories 5 (chitin-glucan) and 6 (mannan-glucan) (Table 2). Besides these main polysaccharides, some minor components of the cell wall may also play important roles in pathogenicity, as antigens, or as virulence factors, and they will be mentioned in this review.