Acid ceramidase of macrophages traps herpes simplex virus in multivesicular bodies and protects from severe disease. Acid ceramidase of macrophages traps herpes simplex virus in multivesicular bodies and protects from severe disease

Macrophages have important protective functions during infection with herpes simplex virus type 1 (HSV-1). However, molecular mechanisms that restrict viral propagation and protect from severe disease are unclear. Here we found that macrophages take up HSV-1 via endocytosis and transport the virions into multivesicular bodies (MVBs). In MVBs, acid ceramidase (aCDase) converts ceramide into sphingosine and increases the formation of sphingosine-rich intraluminal vesicles (ILVs). Once HSV-1 particles pass MVBs, sphingosine-rich ILVs bind to HSV-1 particles, which restricts fusion with the limiting endosomal membrane and prevents cellular infection. Lack of aCDase in macrophage cultures or in Asah1–/– mice results in replication of HSV-1 and Asah1–/– mice died soon after systemic or intravaginal inoculation. The treatment of macrophages with sphingosine enhancing compounds blocks HSV-1 propagation, suggesting a therapeutic potential of this pathway. In conclusion, we demonstrate that aCDase loads ILVs with sphingosine, which prevents HSV-1 capsids from penetrating into the cytosol. Overall design: 3 to 4 independent experiments were performed using different mice for isolation of macrophages and fibroblasts respectively.