The antimicrobial protein RNase 7 directly restricts herpes simplex
virus infection of human keratinocytes
Abstract
Approximately 22% of moderately to severely affected atopic dermatitis
(AD) patients have a history of eczema herpeticum, a disseminated rash
primarily caused by herpes simplex virus type 1 (HSV-1). Reduced
activity of antimicrobial peptides may contribute to the increased
susceptibility of AD patients to HSV-1. We previously demonstrated that
the antimicrobial protein RNase 7 promotes self-DNA sensing by human
keratinocytes, thereby strengthening their resistance to HSV-1
infection. Here, we investigated the effects of RNase 7 in the absence
of exogenously added costimulatory DNA. Recombinant RNase 7 restricted
HSV-1 gene expression, genome replication, and plaque formation in human
keratinocytes. It decreased HSV-1 immediate-early transcripts
independently of the induction of interferon-stimulated genes. Its main
effect was on intracellular infection processes and not on extracellular
virions or virus binding to cells. RNase 7 reduced the amount of
cell-associated capsids and the HSV-1 envelope glycoprotein D at 3 but
not at 0.5 h post-infection, suggesting that it promoted the degradation
of incoming viral particles. Our data show that RNase 7 directly
restricts HSV-1 infection of human keratinocytes, suggesting that it
limits HSV-1 spread in the skin, and thereby disseminated infection.
Previously described mechanisms that reduce RNase 7 activity in the
lesional skin of AD patients may increase their susceptibility to eczema
herpeticum.