A spinach packed with HIV suppressing proteins??

Researchers have investigated the idea of using plants as "factories" to produce and deliver vaccines, but Dr. Alexander Karasev of Thomas Jefferson University in Philadelphia, Pennsylvania is among the first to focus on HIV.

The Pennsylvania researchers focused on "tat" -- a protein that helps HIV reproduce within cells and, at the same, works to suppress the activity of the human immune system. For this reason, tat is an ideal target for the development of both a preventive vaccine and as a treatment for those already infected with HIV.

But why use plants to produce and deliver such a vaccine? The essential point is that vaccines are a very expensive business, so anything that can drive the cost down will be beneficial. Vaccines that grow naturally in plants would be much cheaper to harvest than those produced in the lab.

In their experiments, Karasev's team introduced a gene expressing the HIV tat protein into a common plant virus. Once spinach was infected with the virus, it began to work as a "plant factory" for production of tat.

Human trials involving plant-based delivery of a rabies vaccine have shown that the human immune response can be "primed'' to recognize rabies using this method, and Karasev is hopeful that researchers can reproduce the same results with HIV.

Annual Meeting of the American Society for Microbiology Orlando, FA May 22, 2001