A research group led by Dr. Zongqiang Cui from Wuhan Institute of Virology, Chinese Academy of Sciences made progress on a cell-assisted technique to construct quantum-dot (QD)-encapsulated infectious HIV-1 particles for real time imaging the viral infection in macrophages and published their work on ACS Nano.
Macrophages are one of the major targets of HIV-1 virus, but the viral entry pathway remains poorly understood in these cells. Researchers constructed a quantum dot (QD)-encapsulated infectious HIV-1 particle to track viral entry at a single-particle level in live human primary macrophages. The researchers made the QD-encapsulated particles by conjugating a viral accessory protein Vpr with the QDs that they then incorporated into virion particles during virus assembly. With the labeled particles, Cui and colleagues monitored the early phase of viral infection in real time and observed that, during infection, HIV-1 was endocytosed in a clathrin-mediated manner; the particles were translocated into Rab5A-positive endosomes, and the core was released into the cytoplasm by viral envelope-mediated endosomal fusion. Additionally, they observed that a dynamic actin cytoskeleton is critical for HIV-1 entry and intracellular migration in primary macrophages. The study revealed a productive entry pathway in macrophages that requires both endosomal function and actin dynamics, which may help in the development of inhibitors that block the HIV from entering macrophages.