Monoclonal IgM antibodies raised against Candida albicans Hyr1 provide cross-kingdom protection against Gram negative bacteria

Abstract

Recent years have seen an unprecedented rise in the incidence of multidrug resistant (MDR) Gram negative bacteria (GNB) such as Acinetobacter and Klebsiella species. In view of the shortage of novel drugs in the pipeline, alternative strategies to prevent and treat infections by GNB are urgently needed. Previously, we have reported that the C. albicans hyphal-regulated protein Hyr1 shares striking 3D structural homology with cell surface proteins of A. baumannii; and active or passive vaccination with rHyr1p-N or anti-Hyr1p polyclonal antibody, respectively; protect mice from Acinetobacter infections. Here, we show that monoclonal antibodies (mAb) generated against Hyr1p, bind to the surface of Acinetobacter as well as K. pneumoniae. The anti-Hyr1 mAb also block damage to primary endothelial cells by the bacteria, and protect mice from lethal pulmonary infections mediated by A. baumannii and K. pneumoniae. Our current studies emphasize the potential of harnessing Hyr1p mAb as a cross-kingdom immunotherapeutic strategy against MDR GNB.