By procuring such detailed images, Ladinsky and Bjorkman were able to confirm several observations of HIV made in prior, in vitro studies, including the structure and behavior of the virus as it buds off of infected cells and moves into the surrounding tissue and structural details of HIV budding from cells within an infected tissue. The team also described several novel observations, including the existence of "pools" of HIV in between cells, evidence that HIV can infect new cells both by direct contact or by free viruses in the same tissue, and that pools of HIV can be found deep in the gut.
"The study suggests that an infected cell releases newly formed viruses in a semisynchronous wave pattern," explains Ladinsky. "It doesn't look like one virus buds off and then another in a random way. Rather, it appears that groups of virus bud off from a given cell within a certain time frame and then, a little while later, another group does the same, and then another, and so on."
The team came to this conclusion by identifying single infected cells using electron microscopy. Then they looked for HIV particles at different distances from the original cell and saw that the groups of particles were more mature as their distance from the infected cell increased.
"This finding showed that indeed these cells were producing waves of virus rather than individual ones, which was a neat observation," says Ladinsky.
In addition to producing waves of virus, infected cells are also thought to spread HIV through direct contact with their neighbors. Bjorkman and Ladinsky were able to visualiz
|Contact: Deborah Williams-Hedges|
California Institute of Technology