Aspergillus niger α-1,3-glucan acts as a virulence factor by inhibiting the insect phenoloxidase system

Abstract

Phenoloxidase (PO) is a key enzyme in the melanization process involved in elimination of pathogens in insects. The PO system is rapidly activated in response to pathogen recognition. Inhibition of PO activity can be a way to avoid immune response and increase infection effectiveness. In this study, the effects of inoculation of Galleria mellonella larvae with Aspergillus niger α-1,3-glucan and conidia on PO activity in hemolymph are analyzed in comparison with the effects of β-1,3/1,6-glucan inoculation. Our results indicate that α-1,3-glucan, a fungal cell wall polysaccharide, can play a role of a virulence factor involved in inhibition of the insect PO system.

Keywords: Aspergillus niger; Galleria mellonella; Host-pathogen interaction; Innate immunity; Phenoloxidase; Virulence factor; α-1,3-Glucan.