Delaying Photobleaching of a Light-Switch Complex for Real-Time Imaging of Single Viral Particle Uncoating

Single-Particle Tracking Reveals the Interplay between HIV-1 Reverse Transcription and Uncoating

Reverse transcription uses the reverse transcriptase enzyme to synthesize deoxyribonucleic acid (DNA) from a ribonucleic acid (RNA) template. This plays an essential role in viral replication. There are still, however, many unknown facts regarding the timing and dynamic processes involved in this life stage. Here, three types of dual-fluorescence human immunodeficiency virus type-1 (HIV-1) particles were constructed with high infectivity, and the sequential process of reverse transcription was observed by real-time imaging of a single HIV-1 particle. Viral uncoating occurred at 60-120 min post infection. Subsequently, at 120-180 min post infection, the viral genome was separated into two parts and reverse-transcribed to generate a DNA product. Nevirapine (NVP), a reverse transcriptase inhibitor, can delay the dynamic process. This study revealed a delicate, sequential, and complex relationship between uncoating and reverse transcription, which may facilitate the development of antiviral drugs.

Viscosity sensitive endoplasmic reticulum fluorescent probes based on oxazolopyridinium

A series of viscosity sensitive fluorescent probes 1a-e were synthesized by linking coumarin and oxazolopyridinium via dimethylene in this paper. The viscosity test of probes 1a-e indicated that the fluorescence intensity of the probes enhanced significantly with the increase of viscosity of the system (0.89-865 cP), and exhibited a nearly OFF-ON response to viscosity at 648 nm, 650 nm and 650 nm, respectively. In addition, cells still had a high survival rate after co-culturing with probes 1a-e for 12 h (94-98%). Meanwhile, the laser confocal experiment showed that the variation of the carbon chain length in the oxazolopyridinium could affect the subcellular region of the localization of the probes in cells. When the length of the carbon chain in oxazolopyridinium was between n-C7H15 and n-C12H23, probes 1b-d had the ability to target the endoplasmic reticulum in the cells. Moreover, probes 1b-d showed no significant change in fluorescence intensity after 35 min of continuous laser confocal irradiation, indicating that they had excellent anti-photobleaching properties.