Watching HIV Bud from Cells

Study Shows Last-Minute Role of Protein Named ALIX

University of Utah physics doctoral student Pei-I Ku prepares a sample for the digital microscope she uses to make movies and photographs of the AIDS-causing human immunodeficiency virus budding from human cells in the laboratory. The microscope is in a glass chamber to keep the cells at body temperature so researchers can watch the process over time. Ku is the first author of a new study in which University of Utah researchers combined imaging technology and biochemistry to make such images. The method revealed that a protein named ALIX gets involved in the process later than believed previously. Photo Credit: Tom Bear ( for the University of Uta

May 16, 2014 – University of Utah researchers devised a way to watch newly forming AIDS virus particles emerging or “budding” from infected human cells without interfering with the process. The method shows a protein named ALIX gets involved during the final stages of virus replication, not earlier, as was believed previously.

“We watch one cell at a time” and use a digital camera and special microscope to make movies and photos of the budding process, says virologist Saveez Saffarian, an assistant professor of physics and astronomy and senior author of a new study of HIV budding published online today in the Public Library of Science journal PLOS ONE.

“We saw ALIX recruited into HIV budding for the first time,” he says. “Everybody knew ALIX is involved in HIV budding, but nobody could visualize the recruitment of ALIX into the process.”

The finding is “fundamental basic science” and has no immediate clinical significance for AIDS patients because ALIX is involved in too many critical functions like cell division to be a likely target for new medications, Saffarian says.

“We know a lot about the proteins that help HIV get out of the cell, but we do not know how they come together to help the virus get out, and it will be in the next 10 to 20 years that we will know a lot more of about this mechanism,” he adds. “Would this be a drug target? Would this be a part of biochemistry used in a therapeutic or biotech industry later on? I can’t tell you now. But if it was not because of our curiosity as a species, we would not have the technology we have today.”

The new study “is nice work,” says HIV budding expert Wes Sundquist, who advised Saffarian and is professor and co-chair of biochemistry at the University of Utah School of Medicine. “It’s of genuine interest for those of us who study the mechanism of HIV assembly.”

The study was funded by the National Science Foundation. Saffarian conducted the study with first author, Pei-I Ku, a University of Utah doctoral student in physics; Mourad Bendjennat, a postdoctoral research associate in physics and astronomy; technician Jeff Ballew; and Michael Landesman, another postdoctoral fellow in physics and astronomy who previously worked in Sundquist’s biochemistry lab.

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