Researchers engineer edible malaria vaccine

Subunit vaccines are safer than traditional vaccines because they only use parts of the virus, bacterium or parasite, and so cannot cause infection. However, they can be expensive and complicated to produce, and this is a problem with infectious diseases common in low-income countries, like malaria, which affects billions of people worldwide. Researchers at the University of California, San Diego, are working on using algae to produce a vaccine at a low cost and in large amounts that blocks the transmission of malaria.

Two proteins on the surface of the malaria-causing parasite, known as Plasmodium falciparum surface protein 25 (Pfs25) and 28 (Pfs28), are targets for malaria prevention, but vaccines against these are difficult to produce because the proteins are a complex three-dimensional shape.

In a collaboration between a group from the Division of Biological Sciences and San Diego Center for Algae Biotechnology and a group from the Center for Tropical Medicine and Emerging Infectious Diseases, researchers successfully engineered an edible green alga, Chlamydomonas reinhardtii, which produced the proteins in the right shape. The proteins triggered antibodies in mice that blocked the transmission of malaria from mosquitoes. The next step is to test these algae proteins in humans, and also to find out if they could be used as an edible vaccine rather than an injected one.

"It's too costly to vaccinate two billion people using current technologies," explained Stephen Mayfield, a professor of biology at UCSD. "Realistically, the only way a malaria vaccine will ever be used is if it can be produced at a fraction of the cost of current vaccines. Algae have this potential because you can grow algae any place on the planet in ponds or even in bathtubs." James Gregory, one of the researchers, noted that this means there is the opportunity to "produce enough of this vaccine that we can think about inoculating two billion people. In no other system could you even begin to think about that."

Malaria vaccines (and other vaccines) produced from algae could be a cheaper alternative to traditional vaccine production processes, because they are low-cost, easy to grow in small and large quantities and reproduce quickly. They also have few contaminants, so it's simple to purify the resulting proteins, as well as safer for the people being vaccinated. And if they could be eaten--even better. Malaria vaccine shake, anyone?

- read the press release
- see the paper in PLoS One

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