Antiviral protein which inhibits the replication of viruses by recruiting the cellular RNA degradation machineries to degrade the viral mRNAs (PubMed:32866210). Binds to a ZAP-responsive element (ZRE) present in the target viral mRNA, recruits cellular poly(A)-specific ribonuclease PARN to remove the poly(A) tail, and the 3'-5' exoribonuclease complex exosome to degrade the RNA body from the 3'- end. It also recruits the decapping complex DCP1-DCP2 through RNA helicase p72 (DDX17) to remove the cap structure of the viral mRNA to initiate its degradation from the 5'-end. Its target viruses belong to families which include retroviridae, including human immunodeficiency virus type 1, filoviridae: ebola virus (EBOV) and marburg virus (MARV), togaviridae: sindbis virus (SINV) and Ross river virus (RRV). Specifically targets the multiply spliced but not unspliced or singly spliced HIV-1 mRNAs for degradation. {ECO:0000269|PubMed:18225958, ECO:0000269|PubMed:21876179, ECO:0000269|PubMed:22720057, ECO:0000269|PubMed:32866210}. [Isoform 1]: Exhibits stronger antiviral activity than isoform 2 against MuLV expression and Semliki forest virus infection (PubMed:18225958). Increased antiviral activity may be due to more efficient targeting to endocytic membranes through S-farnesylation (By similarity). Similarly to isoform 2, prevents HIV-1 infection (PubMed:21876179). {ECO:0000250|UniProtKB:Q3UPF5, ECO:0000269|PubMed:18225958, ECO:0000269|PubMed:21876179}. [Isoform 2]: Positive regulator of RIGI signaling during the innate antiviral immune response. Associates with RIGI to promote its oligomerization and ATPase activity stimulation, leading to robust activation of IRF3 and NF-kappa-B transcription factors and eventually to the expression of type I IFNs and IFN stimulated genes (ISGs) (PubMed:21102435). Similarly to isoform 1, prevents HIV-1 infection (PubMed:21876179). {ECO:0000269|PubMed:21102435, ECO:0000269|PubMed:21876179}. This is the function of ENSG00000105939 (ZC3HAV1, zinc finger CCCH-type containing, antiviral 1).