US company Prodigene has reported success in attempts to genetically engineer maize so that it contains a surface protein from the primate form of HIV. The protein is called gp120, and gp120 from HIV is already being used in several vaccines in development. A form of the protein which can be swallowed is attractive to vaccine researchers because they believe it will elicit a more powerful immune response than an injected form.
"For AIDS, a mucosal vaccine is important in two respects," Stuart Shapiro, of the US National Institute for Allergy and Infectious Diseases told New Scientist this week.
"First, the HIV virus usually gets into the body through the mucosa, when it is transmitted sexually - so to have a good mucosal immune response is really important," he says. "Second, a mucosal vaccine is safer than an injectable vaccine in the developing world, where needles get re-used and are not sterilized properly."
The findings were presented at the Keystone symposium in Boulder, Colorado, an annual meeting on HIV basic research that attracts many of the leading researchers in the field.
The next step will be to feed the maize to monkeys to see whether they develop an immune response to the protein. Once this proof of concept work has been carried out, the way could be open to attempting the expression of other HIV proteins in food crops. Maise is particularly atttractive because it can be dried, processed and stored for long periods.
However, it is unlikely that an orally administered vaccine would be the sole form of protection against HIV that would be needed.
To find out more about HIV vaccines in development, click here to view the aidsmap guide to vaccine science.