Acambis smallpox vaccine may help block Aids virus

Shares in the biotech group Acambis jumped yesterday after a new study in the United States suggested that its smallpox vaccine might also be useful in preventing Aids.

Acambis is in exclusive talks with the National Centre for Biodefence at the George Mason University in Virginia about funding its further work on the links between the two diseases. The company - which is supplying the American government with enough smallpox vaccine to innoculate the entire US population against a bioterrorist attack - saw its shares rise 4 per cent to 381.5p.

Researchers at George Mason said laboratory tests showed that blood cells taken from people vaccinated against smallpox were four times more resistant to the Aids virus than those taken from unvaccinated subjects.

Ken Alibek, executive director for education at the centre and a former director of Soviet Union smallpox research before he defected to the West, said that the eradication of smallpox in 1980 may have reduced the natural immunity which allowed the spread of HIV. Mr Alibek said: "Our outcomes are very encouraging. Additional studies that may lead us to more definitive conclusions are already under way."

Acambis played down the research, saying it was at an early stage, involving only 20 people, but added that the findings were very interesting. John Brown, chief executive, said: "Acambis is aware that these findings have been discussed with a number of key experts in this field. Discussions are ongoing with George Mason concerning collaborative work to corroborate the data they have produced."

A rival company, Bavarian Nordic, is already trialling its smallpox vaccine as a preventative treatment for Aids. George Mason conducted its research using Dryvax, the smallpox vaccine produced by Acambis's rival, Wyeth. The Acambis product is a variation on the same strain of cowpox virus used by Wyeth.

Mr Alibek said he will conduct bigger studies aimed at proving the connection between smallpox and HIV protection, and also attempting to discover the means by which the vaccine might be working. Smallpox and HIV both use the CCR5 receptor, which sits on the surface of human cells, as a way in to infect the cells.

Andrew Pendrill, analyst at ABN Amro, said: "This data has not been published in a journal and must therefore be treated with caution.

"However, the lead investigator has a strong background in smallpox research and the data confirms earlier data on HIV-infection rates in the elderly, smallpox-vaccinated population."