Sporothrix schenckii Peptidorhamnomannan-Associated Protein 2 (Pap2) Is Involved in Adhesion and Virulence.

INTRODUCTION

The Sporothrix schenckii cell wall has been widely studied to understand its role in pathogenesis and the infection process. Previously, a component of the cell wall, the peptidorhamnomannan (PRM), was analyzed, and some proteins with unknown function were identified. Among them, the protein encoded by the SPSK_06559 gene stood out for its high abundance within PRM.

METHODS

In this work, in silico analyses were performed to predict the adhesive properties of the SPSK_06559 protein (renamed as Pap2) to extracellular matrix (ECM) components, such as fibrinogen, fibronectin, and type-I and type-II collagen. Subsequently, a recombinant Pap2 (rPap2) version was generated to obtain experimental evidence of its adhesive properties to ECM components. Finally, the role of Pap2 in pathogenesis was assessed in Galleria mellonella larvae.

RESULTS

Bioinformatic analyses consistently suggested that Pap2 possesses adhesive properties. Prediction was experimental validated: rPap2 showed strong adhesion to ECM components. Immunization with rPap2 conferred significant protection to G. mellonella larvae against a lethal dose of S. schenckii. Furthermore, preincubation of fungal cells with anti-rPap2 antibodies drastically reduced their ability to kill the larvae.

DISCUSSION: These findings demonstrate that the SPSK_06559 protein (Pap2) participates in the initial adhesion to host tissues. Induction of a protective response through immune priming with rPap2 suggest that Pap2 is a promising immunogenic antigen. Reduction of lethality upon blocking Pap2 confirms its essential role in pathogenesis, positioning it as a potential target for the development of new therapies and vaccines against sporotrichosis.