Dutch biotechnology company Crucell N.V. and Harvard Medical School announced results of a joint study supporting novel vaccine vectors developed by Crucell.

The results were outlined in a paper presented by Dr. Dan Barouch of Harvard Medical School and the Beth Israel Deaconess Medical Centre to the AIDS Vaccine 2004 conference in Lausanne, Switzerland. Dr. Barouch reported results concerning the potency of adenovirus serotypes 11 and 35 (rAd11 and rAd35) when combined with antigens of simian immunodeficiency virus (SIV), a virus that causes AIDS-like symptoms in monkeys.

According to a release, the results showed both recombinant serotypes were extremely effective in eliciting immune responses in mice, particularly when used together in a prime-boost vaccine regimen in the presence of pre-existing immunity to the most commonly used recombinant adenovirus vaccine vector, serotype 5 (rAd5). Pre-existing immunity is a characteristic that is likely to blunt immune responses and hamper the efficacy of rAd5 vaccines.

Crucell's AdVac technology is designed to manage the problem of pre-existing immunity in humans against rAd5. It does this by employing adenovirus vectors that don't regularly occur in the human population, such as rAd35 and rAd11. The new results supporting the effectiveness of these vectors build on an earlier paper published by the Crucell-Harvard partnership in the Journal of Immunology in May 2004.

"These are very promising results for our AdVac vaccine technology and further confirm the platform's quality, particularly for diseases rampant in the developing world, such as HIV, malaria and TB," said Jaap Goudsmit, Crucell's CSO. "Because AdVac vectors are produced on Crucell's PER.C6 technology, production at the scale required for mass vaccination is within reach," he added.

While no adenovirus-based recombinant vaccines are currently licensed for general use, the scientific community is testing the ability of these vaccines to counter viruses such as HIV, hepatitis B and Ebola. Recombinant vaccines are necessary for these diseases since inactivated whole virus vaccines are either ineffective or too difficult or dangerous to produce. The AdVac platform is also being applied by Crucell in the production of a malaria vaccine under a cooperative Research and Development Agreement with the National Institute of Allergy and Infectious Diseases at the NIH, the result added.