June 29, 2012
In August of 2011, researchers from the laboratory of David Baltimore published a high profile paper in the journal Nature suggesting that cell-to-cell HIV transmission facilitates ongoing viral replication in the face of antiretroviral therapy (ART). The authors proposed that this might represent a mechanism that sustains the reservoir of HIV-infected cells in people on long-term ART.
A new study by Marc Permanyer and colleagues, published online recently by the Journal of Virology, disputes the Baltimore lab's interpretation of their results. The essence of the disagreement relates to the method used to measure cell-to-cell HIV spread in a laboratory culture system. The original study used a modified HIV that expresses a green fluorescent protein (GFP) tag, and assessed whether the tag became detectable in cells as a surrogate for viral replication. Permanyer's work shows that transfer of HIV from cell-to-cell, as measured by GFP, does not necessarily equate to continuation of the viral replication cycle. In the presence of ART, the transfer is shown to be abortive because replication is blocked. The researchers conclude: "data on cell-to-cell spread should be taken with caution as it is crucial to correctly distinguish and measure abortive virus transfer or subrogate markers of infection (LTR-driven GFP) from effective viral replication."
Richard Jefferys is the coordinator of the Michael Palm HIV Basic Science, Vaccines & Prevention Project Weblog at the Treatment Action Group (TAG). The original blog post may be viewed here.
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