Scedosporium apiospermum, Scedosporium aurantiacum, Scedosporium minutisporum and Lomentospora prolificans: a comparative study of surface molecules produced by conidial and germinated conidial cells

Abstract

BACKGROUND Scedosporium/Lomentospora species are opportunistic mould pathogens, presenting notable antifungal resistance.OBJECTIVES/METHODSWe analysed the conidia and germinated conidia of S. apiospermum (Sap), S. aurantiacum (Sau), S. minutisporum (Smi) and L. prolificans (Lpr) by scanning electron microscopy and exposition of surface molecules by fluorescence microscopy.FINDINGSConidia of Sap, Smi and Sau had oval, ellipsoidal and cylindrical shape, respectively, with several irregularities surrounding all surface areas, whereas Lpr conidia were rounded with a smooth surface. The germination of Sap occurred at the conidial bottom, while Smi and Sau germination primarily occurred at the centre of the conidial cell, and Lpr germination initiated at any part of the conidial surface. The staining of N-acetylglucosamine-containing molecules by fluorescein-labelled WGA primarily occurred during the germination of all studied fungi and in the conidial scars, which is the primary location of germination. Calcofluor white, which recognises the polysaccharide chitin, strongly stained the conidial cells and, to a lesser extent, the germination. Both mannose-rich glycoconjugates (evidenced by fluoresceinated-ConA) and cell wall externally located polypeptides presented distinct surface locations and expression according to both morphotypes and fungal species. In contrast, sialic acid and galactose-containing structures were not detected at fungal surfaces.MAIN CONCLUSIONSThe present study demonstrated the differential production/exposition of surface molecules on distinct morphotypes of Scedosporium/Lomentospora species.

Ultrastructural viewpoints on the interaction events of Scedosporium apiospermum conidia with lung and macrophage cells

“… 2 , 9 , 10 In this line area, our group has demonstrated that conidial cells of S. apiospermum , S. aurantiacum , S. minutisporum and Lomentospora prolificans germinate in vitro under different growth conditions, initially forming a germ tube-like projection that grows in size forming long hyphae. 2 , 9 , 11 , 12 , 13 , 14 The interaction among these hyphae gives rise to a structure resembling a mature biofilm, which could contribute to the increased ability of the fungus to disseminate and evade host immune attacks. 12 , 13 …”

Biochemical and structural studies of target lectin SapL1 from the emerging opportunistic microfungus Scedosporium apiospermum

“…In comparison with pathogenic bacteria, which have been the focus of attention for several years, there is a lack of information about the virulence factors and host recognition systems of pathogenic fungi [50]. This hinders the development of new drugs against these microorganisms, while their resistance to the current ones is progressing quickly [13,24,49]. Therefore, there is an urgent need to obtain information that may contribute to the development of new antifungal agents.…”

“…Conidial adhesion is mediated by cell surface molecules (CSM), including different types of carbohydrates such as polysaccharides and glycoconjugates. Some of the most important carbohydrate CSM described to date for Scedosporium species include peptidorhamnomannans (PRMs) [18][19][20] α-glucan [21], melanin [22], ceramide monohexosides [18,23], Nacetyl-D-glucosamine-containing molecules [24] and mannose/glucose-rich glycoconjugates [18]. The presence and/or abundance of these molecules on the cell surface varies according to the stage of development and is of great relevance to understand fungal pathobiology [18].…”

Sialic acid and biology of life: An introduction

“…fumigatus pathogenic variety reveals greater sialic acid density as compared to that of non-pathogenic Aspergillus species [170]. Scedosporium apiospermum (S. apiospermum), Scedosporium aurantiacum (S. aurantiacum), Scedosporium minutisporum (S. minutisporum), and Lomentospora prolificans (L. prolificans) reveal lack of sialic acid [171,172].…”