The function of OAS3 (2'-5'-oligoadenylate synthetase 3, ENSG00000111331) is as follows. Interferon-induced, dsRNA-activated antiviral enzyme which plays a critical role in cellular innate antiviral response. In addition, it may also play a role in other cellular processes such as apoptosis, cell growth, differentiation and gene regulation. Catalyzes preferentially the dimerization of ATP to form 2'-5'-diadenylate (2- 5A), but can also form the trimeric 2'-5'-oligoadenylate. The oligoadenylate then binds to the inactive monomeric form of ribonuclease L (RNase L) leading to its dimerization and subsequent activation. Activation of RNase L leads to degradation of cellular as well as viral RNA, resulting in the inhibition of protein synthesis, thus terminating viral replication. Can mediate the antiviral effect via the classical RNase L-dependent pathway or an alternative antiviral pathway independent of RNase L. Displays antiviral activity against Chikungunya virus (CHIKV), Dengue virus, Sindbis virus (SINV) and Semliki forest virus (SFV). {ECO:0000269|PubMed:19056102, ECO:0000269|PubMed:19923450, ECO:0000269|PubMed:9880533}.