Malaria vaccine en route to human clinical trial

Scientists have created a vaccine that stops the parasite Plasmodium falciparum, responsible for malaria, to multiply and enter the blood stream. The vaccine was 100 per cent effective in mice; human trials will begin in 2010.

Malaria is considered the leading cause of death in developing countries, with over 350-500 million cases of disease and over one million cases of death per year according to the CDC. To date, only antimalarial drugs can be taken to prior to or during the early stages of the disease; there is no vaccine available. Normally once the parasite Plasmodium falciparum enters a human host (by way of an infected mosquito), it invades the liver. The parasite then replicates itself, during which time it does not cause disease. By the time the body’s immune system has mounted a response, however, the parasite army has left the liver, having spread to the blood stream where severe disease and death occurs. Scientists from the Seattle Biomedical Research Institute, the Walter and Eliza Hall Institute in Australia, and the Walter Reed Army Institute for Research have determined that by deleting genes that regulate P. falciparum’s replication, the parasite is alive long enough in the liver for the immune system to recognize and destroy it and any future “incoming mosquito-transmitted deadly parasites.” According to the researchers,

This approach to vaccine development – using a weakened form of the whole organism that causes a particular disease – has proven successful in eradicating smallpox and controlling diseases such as flu or polio.

The vaccine has already been tested in human liver cells and mice with human liver cells with success. Human clinical trials are set to begin in early 2010.