New Trick That Lets HIV Overcome a Barrier to Infection Uncovered

by Rajashri on Sep 6 2008 4:25 PM

A new trick that enables HIV to overtake resting T cells, which are normally highly resistant to infection has been uncovered by US researchers.

Their findings, published in the journal Cell, suggest that the binding of the virus to the surface of T cells sends a signal that breaks down the internal skeleton of the cells, which might otherwise present a significant barrier to infection.

The researchers have revealed that the binding of HIV to the receptor called CXCR4 activates cofilin, a protein that disassembles actin microfilaments in the resting T cells, which are important building blocks of the cytoskeleton.

Since this process is necessary for the virus to infect the resting cells, the researchers say that it may provide a useful new target for therapy.

"The ability of co-receptor engagement to alter intracellular biochemistry suggests that exposure of cells to HIV may in fact prime cells for HIV infection," said Yuntao Wu of George Mason University and Jon Marsh of the National Institute of Mental Health.

"When actin is cut, it grows back. That process may carry the virus from the cortical actin to inside the nucleus," Wu added.

HIV's newfound ability to rearrange the cytoskeleton of resting T cells with the help of cofilin may not be necessary in active memory T cells, Wu said, because cells that are actively cycling and migrating disassemble elements of the cytoskeleton themselves, leaving them naturally more susceptible to HIV's entry.

"This is the first time we've been aware of cofilin's activity in HIV infection of resting CD4 T cells," Wu said.

The researchers say that further study is needed to identify exactly how the virus interacts to effect this change in cells, and to further explore its potential as a target for treatment.

"This shows how much more we can learn. HIV has evolved to utilize a great number of normal cellular processes. This is just another one," Marsh said.