A mapmaker and a mathematician may seem like an unlikely duo, but together they worked out a way to measure longitude - and kept millions of sailors from getting lost at sea. Now, another unlikely duo, a virologist and a biophysicist at Rockefeller University, is making history of its own.
By using a specialized microscope that illuminates only a cell's surface, they have become the first to see, in real time and in plain view, hundreds of thousands of molecules coming together in a living cell to form a single particle of the virus that has, in less than 25 years, claimed more than 25 million lives: HIV.
Not only may this work, published in the May 25 advance online issue of Nature, prove useful in developing treatments for the millions around the globe still living with the lethal virus, but the technique created to image its assembly may also change the way scientists think about and approach their own research.
"The use of this technique is almost unlimited," says Nolwenn Jouvenet, a postdoc who spearheaded this project under the direction of HIV expert Paul Bieniasz and cellular biophysicist Sanford Simon, who has been developing the imaging technique since 1992. "Now that we can actually see a virus being born, it gives us the opportunity to answer previously unanswered questions, not only in virology but in biology in general."
Unlike a classical microscope, which shines light through a whole cell, the technique called total internal reflection microscopy illuminates only the cell's surface, where HIV assembles. "The result is that you can see, in exquisite detail, only events at the cell surface. You never even illuminate anything inside of the cell so you can focus on what you are interested in seeing the moment it is happening," says Simon, professor and head of the Laboratory of Cellular Biophysics.
When a beam of light passes through a piece of glass to a cell's surface, the energy from the light propagates upward, illuminating the entire cell. But when that beam is brought to a steeper angle, the light's energy reflects off the glass coverslip and propagates downward, illuminating only the events going on at its most outer membrane. By zeroing in at the cell's surface, the team became the first to document the time it takes for each HIV particle, or virion, to assemble: five to six minutes. "At first, we had no idea whether it would take milliseconds or hours," says Jouvenet. "We just didn't know."
"This is the first time anyone has seen a virus particle being born," says Bieniasz, who is an associate professor and head of the Laboratory of Retrovirology at Rockefeller and a scientist at the Aaron Diamond AIDS Research Center. "Not just HIV," he clarifies, "any virus."