Near-infrared fluorescent proteins iRFP is derived from bacterial phytochrome photoreceptors (BphPs). Due to its red-shifted excitation/emission spectrum, iRFP has much lower tissue background than the other fluorescent proteins when used for in vivo imaging. This iRFP lentivirus expresses miRFP670 under the control of the CMV promoter, with hygromycin as a selection marker.