Viruses catch an endocytic ride into the cell

Sometimes the story is in knowing how to connect the dots (or electron micrographs). In 1978, Ari Helenius took his laboratory—which had already made a name for itself in isolating and characterizing membrane proteins—in a new, cellular direction. He emerged with a biological storyboard composed of electron microscopy (EM) snapshots.

Helenius wanted to figure out how viruses enter cells—an important question from the literature—but admits that starting out he “didn't have the mindset of a cell biologist.” The individual results of those first experiments following Semliki Forest virus (SFV) into cultured mammalian cells by immunofluorescence and EM were clear, Helenius says, “but I couldn't put them in context.”

A meeting in Berlin in the spring of 1978 helped change his perspective. There he rubbed elbows with “the big cell biology crowd,” including George Palade, Christian de Duve,...