Passing the Viral Baton
Rowena Johnston, Ph.D.
July 29, 2009–amfAR research fellow Dr. Jing Jin, at Yale University School of Medicine, has helped solve one of the mysteries surrounding virus assembly and transmission in a paper published in the online journal PLoS Biology. Click here for video.
For more than ten years, researchers have known that retroviruses such as HIV infect target cells hundreds or even thousands of times more efficiently when an infected cell makes contact with its target and hands off the virus than when the infecting virus is free-floating. The mechanism whereby this viral passing-of-the-baton occurs has now been documented on film by the research group led by Dr. Jin and her mentor Dr. Walther Mothes.
Using four-dimensional (three dimensions of space plus time) microscopy, the team was able to track the assembly of new virus particles, their release from an infected cell, and their transmission to a new target cell.
Newly forming virus particles assemble their parts inside a cell close to the point of contact with another cell. How do these newly assembling viruses “know” which region of the cell membrane is making contact with another cell? Key to the process is the envelope protein (Env) which ultimately comes to surround a mature virus. While the newly forming virus is still assembling, Env is embedded in the membrane of the producer cell. The region of Env that protrudes from the cell’s surface mediates contact with the as yet uninfected cell, while the tail of the Env protein—the region that extends into the inside of the cell—attracts the core structural proteins of the assembling virus.
Jin and her colleagues describe these new findings as “yet another clever adaptation” utilized by the virus. The hope is that scientists can use this information to develop new therapies that outwit the virus.
Dr. Johnston is amfAR’s vice president and director of research.