Researchers Catch HIV on Film
Using high-speed three-dimensional imaging equipment and a version of HIV embedded with a green fluorescent protein, a team of virologists and physicists were recently able to track and film in real-time the process by which an HIV-infected cell passes the virus to other cells. The movie tracked one of HIV’s proteins, known as Gag, as HIV was transmitted from an already infected CD4+ T cell to another CD4+ T cell that it was targeting (http://www.youtube.com/GreenVSLab).
In Day-Glo colors, these movies illustrate what happens when HIV-infected cells collide with uninfected cells and convey how rapidly the Gag proteins—with the help of adhesive contacts called virological synapses that are formed at the juncture of CD4+ T cells—pass from infected cell to uninfected cell.
Together, virologists at Mount Sinai School of Medicine in New York City, who created the fluorescent version of HIV, and physicists at the University of California-Davis, who supplied the expertise in high-speed imaging, produced 12 movies detailing this process. Some depict just a few seconds in the life cycle of the virus, while others—with the help of time-lapsed photography—span several days. Although these short films may not compete with Hollywood blockbusters, after a week on YouTube, one of the short films had more than 150,000 hits.
Benjamin Chen, the Mount Sinai virologist who created the glowing HIV, says a fast video microscope capable of taking three-dimensional images of infected cells every second or so, showed that HIV Gag quickly congregates at the virological synapse, forming a button shape. The footage then shows the viral proteins being ushered into a target cell’s endosome, a membrane-bound compartment that many other viruses use to gain entry into cells but which HIV was not thought to favor much.
Chen says the footage depicting cell-to-cell transfer of HIV could provide valuable insights into new strategies for AIDS vaccine and drug development. —Regina McEnery