IMAGE: For HIV to mature, a crucial cutting point has to be severed. EMBL scientists determined the cutting site’s 3-D structure in whole HIV particles, and found that it is hidden… view more
Credit: IMAGE: Florian Schur/EMBL
A new type of HIV drug currently being tested works in an unusual way, scientists in the Molecular Medicine Partnership Unit, a collaboration between EMBL and Heidelberg University Hospital, have found. They also discovered that when the virus became resistant to early versions of these drugs, it did not do so by blocking or preventing their effects, but rather by circumventing them. The study, published online today in Science, presents the most detailed view yet of part of the immature form of HIV.
HIV, the virus that causes AIDS, comes in two forms: immature and mature. The immature form is assembled inside an infected person’s cells. After an immature virus particle has left the cell, it has to change into the mature form before it can infect other human cells. A new group of drugs that inhibit this maturation is currently undergoing clinical trials, but so far it was unclear how exactly these drugs act.
To go from immature to mature, HIV has to cut the connections between its main building blocks, and rearrange those pieces. John Briggs’ lab at EMBL and Hans-Georg Kräusslich’s lab at Heidelberg University Hospital looked at a particularly important cutting point. It connects building blocks known as the capsid protein and the spacer peptide 1, and if it is not cut, the virus cannot mature. The scientists used a combination of cryo-electron tomography and subtomogram averaging to reveal exactly what this part of the immature form of HIV looks like in 3D. They found that the cutting site is hidden in …