"As part of the 'vaccine' experinent that we will carry out, we will study proteins that may be used in a vaccine against AIDS," Sharipov told reporters at the Star City training centre near Moscow.

Capsules containing the proteins in question will be installed on board the space station, he said, adding that results would be analysed back on earth.

Sharipov and US astronaut Leroy Chiao are due to leave on October 11 to replace the current crew, American Michael Finke and Russian Gennady Padalk, who have been orbiting aboard the ISS since April 21.

A third team member, Russian Yuri Shargin, will also take off from the Baikonur space station in the former Soviet republic of Kazakhstan, to spend 10 days aboard the ISS.

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