Malaria vaccine trials begin using 'chimpanzee virus'

Feb 01, 2008

Trials are underway, funded by the Wellcome Trust, for a new vaccine to combat the most deadly form of malaria. For the first time ever, researchers will use a virus found in chimpanzees to boost the efficacy of the vaccine. The trials will take place at the University of Oxford's Jenner Institute, led by its Director, Professor Adrian Hill.

Malaria, caused by Plasmodium parasites, is one of the world's deadliest killers, killing over a million people each year, mainly women and young children in Africa and SE Asia. The most deadly species , P. falciparum, is responsible for 80% of malaria infections and 90% of deaths. As yet, there is no vaccine against malaria. This is because, for much of their life-cycle, the parasites responsible for infection live inside cells, where they cannot be reached by antibodies.

"We urgently need a vaccine to help in the fight against this deadly killer," says Professor Hill, a Wellcome Trust Principal Research Fellow. "Malaria parasites are able to outwit our immune system by hiding out in the body's cells, however. Finding a way to generate enough immune cells and antibodies to identify and destroy the parasites will be the key to preventing infection."

The vaccine being developed and trialled by Professor Hill's team in collaboration with Okairòs uses the company’s genetically-modified chimpanzee adenovirus to produce the malaria antigen and to stimulate a response to the vaccine in the body. Adenoviruses appear to be particularly potent for increasing the immune response to the malaria vaccine. However, because human adenoviruses, which cause diseases including the common cold and gastroenteritis, are widespread, most people have developed some immunity towards them. Using a chimpanzee adenovirus ensures that a recipient is unlikely to have resistance to this component of the vaccine.

"Chimpanzees have their own set of adenoviruses which rarely infect humans, so we have not built up immunity to them," explains virologist Dr Sarah Gilbert at the Jenner Institute. "This is why we have chosen such a virus to form the backbone of the new vaccine."

Professor Hill's team is currently recruiting for more volunteers for the first trials, which are to assess the safety of the vaccine. Because the active component of the adenovirus is removed, however, there is no danger of transmission to the human of the original chimpanzee virus.

The trial will also be measuring the response of the immune system. The team hopes to generate a response from CD8+ T-cells (sometimes known as killer cells) that should kill the parasites when they enter the liver, where they multiply undetected. However, if the T-cells do not kill all of the parasites, any that escape from liver into the bloodstream will still be able to enter red blood cells and cause illness.

The group plans to test a second vaccine which would then target the parasites in the bloodstream and red blood cells.

“Our ultimate goal is a combination product which targets the parasite at both the liver stage and the blood stage,” says Professor Hill. “Few people still think that you can get really strong protection from malaria based on a single component.”

Over a dozen vaccines have now been made by scientists at the University of Oxford and taken into clinical trials, but this is the first vaccine to have also been manufactured within a UK university, according to Professor Hill.

Source: Wellcome Trust

Explore further: Police seize millions in huge fake Viagra swoop

add to favorites email to friend print save as pdf

Related Stories

An easier way to manipulate malaria genes

Aug 11, 2014

Plasmodium falciparum, the parasite that causes malaria, has proven notoriously resistant to scientists' efforts to study its genetics. It can take up to a year to determine the function of a single gene, ...

Breakthrough in coccidiosis research

Jul 28, 2014

Biological researchers at the Royal Veterinary College (RVC) are a step closer to finding a new cost-effective vaccine for the intestinal disease, coccidiosis, which can have devastating effects on poultry ...

The 'yin and yang' of malaria parasite development

Jul 09, 2014

Scientists searching for new drug and vaccine targets to stop transmission of one of the world's deadliest diseases believe they are closer than ever to disrupting the life-cycle of this highly efficient ...

Recommended for you

Novartis Japan admits concealing drug side effects

19 hours ago

The Japanese unit of Swiss pharma giant Novartis has admitted it did not report more than 2,500 cases of serious side effects in patients using its leukaemia and other cancer drugs, reportedly including some fatalities.

Most US babies get their vaccines, CDC says

Aug 28, 2014

(HealthDay)—The vast majority of American babies are getting the vaccines they need to protect them from serious illnesses, federal health officials said Thursday.

Expression of privilege in vaccine refusal

Aug 27, 2014

Not all students returning to school this month will be up to date on their vaccinations. A new study conducted by Jennifer Reich, a researcher at the University of Colorado Denver, shows that the reasons why children may ...

User comments : 0