Intrabody-based Mapping of Latency-associated Nuclear Antigen from Kaposi’s Sarcoma-associated Herpesvirus Show Conserved Epitopes for Viral Latency Inhibition

Kaposi’s sarcoma associated herpesvirus (KSHV or human herpesvirus 8 [HHV-8]) is a gammaherpesvirus highly associated with KS, primary effusion lymphoma (PEL), and multicentric Castleman’s disease, an aggressive lymphoproliferative disorder. KSHV, like other gammaherpesvirus latently infects predominantly B-cells and endothelial cells. Infected cells retain the virus from one generation to the next existing as a multicopy circular episomal DNA in the nucleus, expressing a limited subset of viral genes. Of these latently expressed genes, LANA1, the latency associated nuclear antigen is highly expressed in all forms of KS-associated malignancies. Various studies so far show that LANA1 tethers the viral episomes to host chromosomes and binds to specific sites within and close to the TR elements contributing to the stable maintenance of the viral episomes in successive daughter cells. Anti-LANA1 intrabody strategies might represent a new therapeutic approach to treatment of KSHV infections, since LANA1 is regained for KSHV latency. In addition, the use of intrabodies can help drug development by mapping LANA1 inhibiting regions. We report development of several LANA1 specific single chain antibodies from immunized rabbits that can be expressed intracellularly, bind to LANA1 epitopes and can be used for functional KSHV studies on viral latency.