Stage of Keratinocyte Differentiation Is a Key Determinant of Viral Susceptibility in Human Skin.

The human epidermis is composed of four visually distinct layers: the stratum basale, stratum spinosum, stratum granulosum, and stratum corneum, which result from a complex differentiation process. This study utilized in vitro viral infection assays with cultured human keratinocytes (KCs), bioinformatic analysis of epidermal single-cell RNA-sequencing datasets, and histopathologic assessment of human viral skin infections (herpes simplex virus [HSV] and varicella-zoster virus [VZV]) to address whether specific KC layers and/or stages of differentiation are more susceptible to viral infection and/or spread.