Table 1.

Antiviral ISGs with known functions.

ISG(s)	Function(s)	Reference(s)
APOBEC3	Cytidine deamination of single-stranded viral DNA (deoxycytidine to deoxyuridine) to inhibit retrovirus replication.	[22,23]
BST2	Binds and inhibits the release of budding progeny virions.	[24,25]
DDX58	RIG-I detects ssRNA to induce MAVS and IRF-dependent type I IFN production.	[9,[26], [27], [28]]
DDX60	Enhances RIG-I and MDA5-dependent type I IFN production.	[29,30]
EIF2AK2	Detects dsRNA and phosphorylates EIF2α to inhibit both cellular and viral mRNA translation.	[31,32]
IFIH1	Detects dsRNA to induce MAVS and IRF-dependent type I IFN production.	[26,28]
IFITM1, IFITM2, and IFITM3	Inhibit viral entry. IFITM3 inhibits the formation of fusion pores in the late endosome.	[[33], [34], [35]]
IRF1 and IRF7	Induce ISG expression in the absence of type I IFN signaling.	[36,37]
ISG15	Regulates host and viral protein function by ISGylation.	[[38], [39], [40]]
ISG20	Cleaves ssRNA to inhibit viral RNA synthesis and replication.	[41,42]
MX1	Forms oligomeric ring structures that bind viral nucleoproteins to inhibit replication.	[[43], [44], [45]]
OAS1, OAS2, and OAS3	Detect dsRNA and synthesize 2′–5′ olygoadenylates, which are the substrate for RNaseL activation.	[[46], [47], [48]]
OASL	Enhances RIG-I activation.	[49]
RSAD2	Restricts viral budding by modulating lipid synthesis.	[50]
SAMHD1	Depletes intracellular dNTPs to inhibit viral replication.	[[51], [52], [53], [54]]
TRIM5	Binds virus capsid proteins to inhibit viral infection.	[55]
TRIM25	Ubiquitinates RIG-I to enhance type I IFN induction.	[56]
ZC3HAV1	Inhibits viral mRNA expression and enhances RIG-I-dependent type I IFN induction.	[57,58]