Structure and Antigenicity of Kaposi's Sarcoma-Associated Herpesvirus Glycoprotein B

Kaposi's sarcoma-associated herpesvirus (KSHV), a member of the human γ-herpesviruses family, exhibits extensive cellular tropism and is associated with Kaposi's sarcoma and various B-cell malignancies. Despite its clinical significance, no effective prophylactic vaccines or specific therapeutics are currently available to prevent or treat KSHV infection. Similar to other herpesviruses, KSHV depends on the envelope glycoprotein B (gB) for host receptor recognition and membrane fusion initiation, making gB a prime target for antiviral antibody or vaccine development. In this study, the high-resolution cryo-electron microscopy (cryo-EM) structure of KSHV gB is presented, revealing a unique trimeric conformation resembling the postfusion state observed in other herpesviruses. Additionally, the structure of the non-neutralizing monoclonal antibody 2C4 bound to KSHV gB domain IV is resolved. The comparative sequence and structure analyses reveal significant homology in neutralizing epitopes between KSHV and Epstein-Barr virus (EBV) gB, indicating a potential pathway for the development of broad-spectrum antiviral strategies. These findings provide a foundation for a deeper understanding of KSHV's infectious mechanism and pave the way for the creation of universal interventions against the human γ-herpesviruses.