Scientific Breakthrough in Malaria Vaccine Development

Scientific Breakthrough in Malaria Vaccine Development

Researchers report that GSK Biologicals' RTS.S/AS02A malaria vaccine candidate protected a significant percentage of children against uncomplicated malaria. infection, and even severe forms of the disease for at least six months. This largest malaria vaccine efficacy trial ever conducted in Africa also re-confirmed the vaccine's safety in one-to-four year old children. Further efficacy studies will be needed before consideration for licensure.

The double blind, controlled trial involved 2,022 children in southern Mozambique and was conducted by the Centro de Investigacao em Saude da Manhiga (CISM). GSK Biologicals and PATH's Malaria Vaccine Initiative (MVI) co-sponsored the trial, which was approved by Mozambique's Ministry of Health.

"Our results demonstrate the feasibility of developing an efficacious vaccine against malaria," wrote CISM's Pedro Alonso, MD, Ph.D., lead author of the Lancet article, adding that "...malaria vaccines could greatly contribute to reducing the intolerable global burden of this disease." Dr. Alonso was the principal investigator of the study and heads the Center for International Health of the Hospital Clinic at the University of Barcelona."It will still take some years before this vaccine becomes a reality, but the commitment is certainly there." said Jean Stephenne, president and general manager of GSK Biologicals, one of the world's largest vaccine companies. We are very encouraged by these results. They demonstrate that a Plasmodium falciparum malaria vaccine based on the circumsporozoite protein is feasible. Such a vaccine could have a major impact on public health. This project demonstrates the power of collaboration between the public and private sectors," he added.

"These findings represent a breakthrough in the science of malaria vaccines," offered Dr. Melinda Moree, Ph.D., director of MVI, a global program created to overcome barriers to malaria vaccine development. "They provide convincing evidence that a vaccine could become part of the world's efforts to spare children and families from the devastating effects of this disease. This brings us another step closer to a licensed vaccine." In 2000, GSK Biologicals and MVI entered into a partnership to develop the vaccine for children. MVI was started in 1999.

According to the study, vaccine efficacy against clinical malaria attacks was 30 percent. Efficacy against primary infection with Plasmodium (P.) falciparum was 45 percent, and efficacy against severe disease was 58 percent. P. falciparum is the parasite that causes the greatest number of cases of malaria in Africa.

"The results of this trial represent a significant scientific advance and an important step forward. In contrast to the previous trials of this vaccine in adults, which suggested that vaccine efficacy was short-lived, protection in these children has lasted at least six months," Dr. Alonso added. Follow-up with the children continues.

A recombinant protein that fuses a part of the P. falciparum circumsporozoite (CS) protein with the hepatitis B surface antigen molecule, RTS,S, has been under development by GSK Biologicals for more than 15 years.

The vaccine is directed against the form of the P. falciparum parasite that is injected by mosquitoes. This form is known as the sporozoite. After immunization. antibodies and white blood cells are produced which can prevent the sporozoite from surviving or from further development in the liver. The vaccine is delivered in a three-dose regimen.

Among infectious diseases, malaria is one of the world's biggest killers. It is estimated that malaria kills between one and three million people in the world's poorest countries every year, and more children in sub-Saharan Africa than any other infectious disease.

Due to the need for further studies, a licensed malaria vaccine is not expected to be available before 2010, by when it is projected that half the world's population, or 3.5 billion people, will be living in areas in which malaria is transmitted. The economic costs of the disease for Africa alone are equivalent to US$12 billion annually.

Bacterial Bad Behaviour Beats Infection
Spiteful fight-to-the-death tactics used by rival bacterial parasites in the desperate search for nourishment can help to reduce the harmfulness of disease symptoms, new research from the universities of Edinburgh and Bath has shown.

A study published in the Proceedings of the Royal Society reveals that bacteria are too busy killing each other to cause severe disease in the organisms that host the parasites.

The lives of bacterial parasites can be extremely vicious. In their aggressive competition for limited resources, bacteria may try to poison each other. Some bacterial cells even unleash the ultimate offensive - they self-destruct, showering lethal toxins over their competitors. The new research into this microscopic battleground has shed light on the motivation for such behaviour. Such vicious behaviours that harm both the perpetrator and any victims present an interesting evolutionary puzzle.

At first it is not easy to see how spite can evolve, because the suicidal bacterium will leave no descendants to carry its genes into future generations. But it can be favoured because the bacterium's kin, which also carry copies of its genes, are immune to the toxins. By killing their competitors, the suicidal act indirectly benefits these kin, and they transmit the genes to future generations.

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