BK virus Large T antigen (BKV LTag)

BK virus Large T antigen (LTag) is a multifunctional regulatory protein and the primary driver of the BK polyomavirus (BKV) life cycle. It is essential for viral DNA replication, serving as an ATP-dependent DNA helicase that unwinds the viral origin of replication. Beyond its replicative role, LTag acts as a potent oncoprotein by binding and inactivating key host cell tumor suppressors, specifically p53 and the retinoblastoma (pRb) protein family, which forces the host cell into the S-phase of the cell cycle to facilitate viral production. In clinical settings, the reactivation of BKV in immunocompromised individuals, particularly kidney and bone marrow transplant recipients, leads to severe complications such as polyomavirus-associated nephropathy (PVAN) and hemorrhagic cystitis. Because LTag is vital for both the maintenance of the viral genome and the transformation of the host cell environment, it is a major focal point for the development of direct-acting antivirals and virus-specific T-cell therapies aimed at controlling BKV-related diseases.

Other names

BKPyV Large T-antigenLarge Tumor antigenPolyomavirus BK Large T antigenLTALT-Ag

Inhibition of viral DNA replication; blocking of protein-protein interactions with host tumor suppressors; adoptive T-cell mediated cytotoxicity targeting LTag epitopes.