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

Abstract

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.

Antibody profiling and predictive modeling discriminate between Kaposi sarcoma and asymptomatic KSHV infection

“…Since the more public Abs against the immunodominant epitopes and discriminative peptides identified in this study mainly target intracellular proteins (LANA) or intracellular domains of membrane proteins (K15), they are unlikely to impart neutralizing activity. However, intrabodies–Abs expressed intracellularly–have been considered as therapeutics for infectious diseases and cancers [ 42 , 43 ], and intrabodies specific to KSHV LANA and vIL-6 have demonstrated some pre-clinical therapeutic potential [ 44 – 46 ]. Additionally, non-neutralizing Abs have been shown to provide protection against other viral infections [ 47 ], and although we have previously reported that the Ab-dependent cell cytotoxicity (ADCC) activity of plasma-derived Abs was not differential between KS and ASY, ADCC-mediating Abs have been detected in KSHV seropositive individuals, and it is possible that NK cell functional differentials may exist between KS and ASY and could target certain anti-KSHV repertoires better than others [ 22 ].…”