An Integrin-Independent Kaposi’s Sarcoma-Associated Herpesvirus Infection Mechanism
Host receptor usage by KSHV has been best studied using primary microvascular endothelial and fibroblast cells, although the virus infects a wide variety of cell types in culture and in natural infections. In these two infection models, KSHV adheres to the cell though heparan sulfate (HS) binding, then interacts with a complex of EphA2, xct, and integrins 3{beta}1, V{beta}3, V{beta}5 to catalyze viral entry. We dissected this receptor complex at the genetic level with CRISPR-Cas9 to precisely determine receptor usage in two epithelial cell lines. Surprisingly, we discovered an infection mechanism that requires HS and EphA2 but is independent of V- and {beta}1-family integrin expression. Furthermore, infection appears to be independent of the EphA2 intracellular domain. We also demonstrated while two other endogenous Eph receptors were dispensable for KSHV infection, transduced EphA4 and EphA5 significantly enhanced infection of cells lacking EphA2.\n\nIMPORTANCEOur data reveals an integrin-independent route of KSHV infection and suggests that multiple Eph receptors besides EphA2 can promote and regulate infection. Since integrins and Eph receptors are large protein families with diverse expression patterns across cells and tissues, we propose that KSHV may engage with several proteins from both families in different combinations to negotiate successful entry into diverse cell types.