miRNA-36 inhibits KSHV, EBV, HSV-2 infection of cells via stifling expression of interferon induced transmembrane protein 1 (IFITM1).

Kaposi's sarcoma-associated herpesvirus (KSHV) is etiologically associated with all forms of Kaposi's sarcoma worldwide. Little is currently known about the role of microRNAs (miRNAs) in KSHV entry. We recently demonstrated that KSHV induces a plethora of host cell miRNAs during the early stages of infection. In this study, we show the ability of host cell novel miR-36 to specifically inhibit KSHV-induced expression of interferon induced transmembrane protein 1 (IFITM1) to limit virus infection of cells. Transfecting cells with miR-36 mimic specifically lowered IFITM1 expression and thereby significantly dampening KSHV infection. In contrast, inhibition of miR-36 using miR-36 inhibitor had the direct opposite effect on KSHV infection of cells, allowing enhanced viral infection of cells. The effect of miR-36 on KSHV infection of cells was at a post-binding stage of virus entry. The highlight of this work was in deciphering a common theme in the ability of miR-36 to regulate infection of closely related DNA viruses: KSHV, Epstein-Barr virus (EBV), and herpes simplexvirus-2 (HSV-2). Taken together, we report for the first time the ability of host cell miRNA to regulate internalization of KSHV, EBV, and HSV-2 in hematopoietic and endothelial cells.