Abstract

Until recently, the analysis of viruses and viral particles by flow cytometry waslimited due to the range of detection (300-500 nm)1 and the low signal-to-noiseratio of traditional flow cytometers in the lower size range. However, thedevelopment of camera-based systems in flow cytometry now allows for theanalysis of viruses and viral particles (VPs). Due to the high sensitivity of thetime-delay integration (TDI) and CCD-camera technology that is unique toAmnis® systems, the Amnis® CellStream® and ImageStream® flow cytometerscan be used to study viruses and VPs. These flow cytometers also offer a lowsignal-to-noise ratio, which further increases their ability to resolve particles100 nm or smaller.The recent coronavirus pandemic has demonstrated that flow cytometry canbe used as a high-throughput tool for studying viruses and their effects oncells. The research presented here demonstrates the ability of two Amnissystems to analyze VPs. The VPs (MV-M-sfGFP) used in these studies weredeveloped by ViroFlow Technologies, Inc.2 MV-M-sfGFP are inactivatedmurine retroviruses produced in mouse cells that express superfolder greenfluorescent protein (sfGFP) on the outer surface of the viral envelope andhave a size of ~120 nm.First, we analyzed the viral particles on the CellStream Flow Cytometer, whichis a compact, camera-based benchtop system that uses TDI-CCD technologyto deliver highly sensitive small particle resolution with low background noise.Then, we analyzed the viral particles on the ImageStream®X Mk II ImagingFlow Cytometer, which obtains image data in addition to flow cytometric data.The new High Gain mode for ImageStream was used for these experiments inconjunction with a high-powered 400 mW 488 nm laser for increased detectionof viral particle signal.In conclusion, both the Amnis CellStream Flow Cytometer and the AmnisImageStreamX Mk II Imaging Flow Cytometer are excellent choices for flowvirometry.