Reassessing viral dynamics

The influenza virus hijacks receptor-based endocytosis to invade a cell, moving from early endosomes through to late endosomes before fusing with the endosomal membrane to release its genetic material. This complex process is thought to involve two pH changes, one from extracellular pH to early endosome pH (~pH 6) and a second change to late endosomal pH (~pH 5), with the late pH change an absolute requirement for influenza fusion. How the viral cargo is transported and matures has been unclear, with difficulties in real-time imaging of endocytic traffic representing a major obstacle to further developments. In the July 14 PNAS, Melike Lakadamyali and colleagues at Harvard University have designed a strategy to track individual influenza viruses in real time and thus have investigated their movement through the endocytic pathway (PNAS, DOI:10.1073/ pnas.0832269100, July 14, 2003).

Lakadamyali et al. used a fluorescent lipophilic dye in combination with fluorescence microscopy to ...