Table 1.

Selected examples of cellular HIV restriction factors, mechanism of action, and viral counter measures.

Restriction Factor (RF)	RF Mechanism of Action	HIV Counter Reaction	References
APOBEC3G	Encapsidated into virion, induces G-to-A hypermutation during reverse transcription	Vif	[24,25]
IFITMs/IFI16	Excludes viral mRNA from polysome processing, inhibits the protein synthesis	Nef	[26]
SAMHD1	Deoxynucleoside triphosphate triphosphohydrolase 1 activity, prevents reverse transcription	Vpx (only HIV-2)	[25]
SerinC3/5	Incorporated into the virion, inhibits membrane fusion	Nef	[27]
Tetherin/BST-2	Anchors virions on the cell surface of infected cells, inhibits virion release	Vpu	[28,29]
TRIM5α/TRIMCyp/TRIM22	Binds directly to HIV-1 capsids, accelerates uncoating and inhibits reverse transcription	p24-CA variation	[30]