Deletion of afpab1 Causes Increased Sensitivity to Oxidative Stress and Hypovirulence in Aspergillus fumigatus.

Aspergillus fumigatus AFPAB1 is the ortholog of the Aspergillus oryzae cytoplasmic messenger ribonucleoprotein granules AOPAB1 that function to depress the initiation of translation during stress. A. fumigatus can regulate its cellular physiology in response to environmental stresses, but there has been no research on Pab1 in A. fumigatus. The associated gene afpab1 was replaced with a hygromycin-selectable marker to generate the strain Δafpab1. Phenotypic analysis showed that the Δafpab1 grew more weakly than the wild-type strain. Also the germination rate of Δafpab1 was decreased when exposed to oxidative stress. The morphology of Δafpab1 spores also showed great changes. The killing rate of Δafpab1 by RAW264.7 murine macrophage cells was increased, and the reactive oxygen species (ROS) scavenging ability of Δafpab1 was decreased. Pathogenicity testing showed that the deletion strain had decreased virulence. Therefore, we conclude that afpab1 activity is correlated with susceptibility to oxidative stress, and deletion of afpab1 from A. fumigatus possibly leads to observed hypovirulence in an immunosuppressed mouse model.