Scientists have engineered one of the "good bacteria" naturally found colonising the human female genital tract to enable it to produce a chemical called cyanovirin-N, which has powerful anti-HIV effects. Just as some people take probiotic yoghurts as an aid to digestion, the researchers think that their modified bug could be added to the bacterial flora growing naturally in the vagina where it could help to protect the host from infection by the AIDS-causing virus. Cyanovirin-N is naturally produced by a type of blue-green algae called Nostoc ellipsosporum, and it has already been shown in primate experiments to be able to prevent HIV from locking onto and penetrating cells in the vagina. Now, Stanford University's Peter Lee and his colleagues have successfully added the gene for cyanovirin-N to the main chromosome of a bacterium called Lactobacillus jensenii, which naturally colonises the vagina. When the modified bacteria were added to the genital tracts of mice, the researchers were subsequently able to detect small amounts of cyanovirin-N being produced locally. This suggests that it might be possible to use these bugs to provide an effective yet cheap and simple additional line of defence against HIV. This would be especially useful in third world countries such as Africa where several million new cases of HIV infection occur each year, largely because women in these countries have little or no access to effective barrier methods of contraception.


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