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HIV vaccines based on the cold virus could make people 鈥渟itting ducks鈥� for HIV infection.
A study led by Steven Patterson of Imperial College London revives an earlier theory that adenoviruses cause an immune 鈥渙wn goal鈥� by priming people鈥檚 immune systems to produce CD4 cells, the cells HIV prefers to infect. Since the viruses are also used in vaccines against malaria and tuberculosis, the finding could be a major blow.
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鈥淰accines containing cold viruses prime the immune system to produce cells HIV prefers to infect鈥�
The problems were first raised in 2007, when the trial of an HIV vaccine that used an adenovirus was stopped after more subjects than expected became infected with HIV. At the time it was suggested that recipients who had previously been exposed to the adenovirus had a heightened susceptibility to HIV infection, but two studies published in July contradicted that (New 杏吧原创, 25 July, p 14).
In the latest twist, Patterson鈥檚 team took CD4 cells from 20 healthy volunteers and exposed them to adenoviruses. They found that CD4 cells from people who had previously been exposed to the viruses increased by up to 8 per cent, while cells from those who hadn鈥檛 been exposed did not multiply. This suggests that re-exposure makes people more vulnerable to HIV infection, the team say (Proceedings of the National Academy of Sciences, ).