Did patients in a failed HIV vaccine trial halted in 2007 become more susceptible to the virus due to the adenoviral vector used to deliver the experimental vaccine? Researchers have speculated this may have been the case, and a new study proposes a mechanism for how this could have occurred. The in vitro linkurl:study,;http://www.pnas.org/content/early/2009/11/13/0907898106 published in the __Proceedings of the National Academy of Sciences__ (__PNAS__) this week, reports that immune cells from people previously exposed to an adenovirus serotype 5 (Ad5) -- similar to the vector used in the Merck-funded STEP trial -- generate activated T cells primed to migrate to mucosal surfaces such as the gut, where they are more available to HIV infection. "I'm not saying you should rule out adenovirus for all time, but you should be aware that there are possible problems with the use of it," Imperial College London vaccine researcher and main author linkurl:Steven...

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