Japan experts develop malaria vaccine
Yomiuri Shimbun/Asia News Network, Japan
Researchers at Osaka University have developed a malaria vaccine that, if found effective in clinical tests due to begin next spring, will become the first successful safeguard against a disease that kills millions of people every year.
A team led by Prof. Toshihiro Horii of the university's Research Institute of Microbial Diseases in Suita, Osaka Prefecture, found that injections of a protein produced by plasmodium, a parasite that causes malaria, produces an antibody that prevents the onset of the disease.
The race to develop a malaria vaccine began in the 1980s but none of those touted as possible breakthroughs has been effective.
Malaria is one of three big killer diseases in the developing world along with tuberculosis and HIV/AIDS.
About 300 million people, mainly those living in tropical and subtropical zones, contract malaria each year, and more than 2 million die.
About 120 Japanese, mainly those who have returned from malarial regions overseas, fall ill with the disease every year.
Plasmodium enters the bloodstream via malaria-carrying mosquitoes, and grows in red blood cells.
Horii's team targeted falciparum malaria, the most dangerous strain of malaria, which kills more than 1 million people a year.
Most of the victims in affected regions, such as Africa and Southeast Asia, are children aged 5 or younger.
Since the death rate among older patients is much lower, experts believe people develop immunity to the disease by repeatedly contracting it during infancy.
However, malarial parasites produce a wide variety of substances capable of disrupting the human immune system, making it difficult for researchers to know which to target.
Horii's team focused on a protein called serine repeat antigen (SERA), which appears to encase the malarial parasites that produce it.
In test-tube experiments, an antibody used to attack SERA also killed the parasites.
Using research conducted in Uganda, the team found that children suffering from malaria who naturally carried the SERA antibody did not develop a fever, a typical symptom of the disease. The same children also carried far fewer parasites than the average malaria patient.
The research team's vaccine is based on SERA that has been artificially produced using a genetically engineered Bacillus colis bacteria.
The researchers said SERA itself is safe, adding it was highly unlikely a SERA-resistant malarial strain would emerge.
The protein's toxicity will be tested on laboratory animals next month, and the first tests on humans will begin in Japan in April.
In a second round of clinical tests, to be conducted in Uganda and Southeast Asia in January 2005, people will be vaccinated just before the start of the malaria season.
"We already have the technology to mass-produce and administer the vaccine," Horii said, "so I believe it will be in practical use within the next five or six years."