OASL (Oligoadenylate Synthetase-Like) antibodies are tools used to study the OASL protein, a member of the oligoadenylate synthetase (OAS) family, which plays a critical role in innate antiviral immunity. Unlike canonical OAS enzymes that synthesize 2'-5'-linked oligoadenylates to activate RNase L and degrade viral RNA, OASL lacks enzymatic activity for this function. Instead, it enhances antiviral responses by mimicking the effects of polyubiquitin to stabilize and potentiate retinoic acid-inducible gene-I (RIG-I), a key sensor of viral RNA. This interaction amplifies type I interferon (IFN) signaling, critical for host defense against RNA viruses like influenza and hepatitis C. OASL also exhibits dual roles: while promoting antiviral immunity, it can suppress type I IFN production in certain contexts, suggesting regulatory complexity in immune balance. OASL antibodies are pivotal in detecting protein expression, localization, and interactions in immune cells or infected tissues. They aid research on viral pathogenesis, autoimmune disorders, and cancer, where OASL dysregulation has been implicated. Recent studies highlight OASL's involvement in non-viral processes, including cell differentiation and inflammation, expanding its relevance beyond virology. These antibodies are essential for elucidating OASL's mechanisms and therapeutic potential in modulating immune responses.