Key malaria parasite discovery raises vaccine hopes
[LONDON] Hopes for a vaccine that would be effective against many different types of the deadliest malaria parasite, Plasmodium falciparum, have been raised by research published today.
Researchers have discovered a single mechanism that the parasite relies on to invade human red blood cells.
"Our findings were unexpected and have completely changed the way in which we view the invasion process," said Gavin Wright, senior co-author of the study and a researcher at the Wellcome Trust Sanger Institute, United Kingdom. "Our research seems to have revealed an Achilles' heel in the way the parasite invades our red blood cells."
Once they have invaded red blood cells, parasites multiply and spread, causing malaria symptoms. To gain entry into the cells the parasites lock onto various receptors that lie on their surface.
One of the challenges for researchers has been that, although several red blood cell receptors have previously been identified, none is essential for entry. The new work has found a single receptor that is absolutely required by the parasite to invade. The finding applies to all 15 strains of P. falciparum that were tested.
The researchers said that a vaccine could consist of a safe version of the parasite, which would cause the immune system to produce antibodies that swing into action under attack from the real parasite. Such a vaccine could take up to 15 years to produce.
There is no malaria vaccine at the moment. The first, RTS,S/AS01, appears to be about 50 per cent effective and may be on the market by 2015 if further trials prove it to be successful.
Vasee Moorthy, technical officer for the WHO's Initiative for Vaccine Research, told SciDev.Net: "This work represents an important scientific discovery that may warrant exploration through vaccine development.
"Development of a second generation malaria vaccine with greater than 80 per cent efficacy by 2025 is an agreed goal."
Immunology experts Colin Sutherland and Eleanor Riley from the UK's London School of Hygiene and Tropical Medicine, said in a statement: "Malaria parasites have an enormous potential to rapidly evolve and evade human interventions.
"So far only a handful of parasite strains have been tested, and so more work is needed on parasites taken directly from patients around the world to verify that blocking this pathway will be effective against all falciparum malaria worldwide."