London, Oct. 2 (Reuters): Scientists have cracked the genetic code of the parasite that causes the most deadly form of malaria, in what has been called a quantum leap in the fight against the disease that kills one child every 20 seconds.
A team of 150 researchers in the US and Britain has sequenced all the genes in the threadlike Plasmodium falciparum parasite that causes malaria, an illness that threatens half of the world’s population. “We’ve provided new tools and new insights, hopefully for new targets for drugs and vaccines, and hopefully for new treatments,” Neil Hall of Britain’s Sanger Institute told a news conference.
The malaria genome, which was published in the science journal Nature today, was announced jointly with the genetic map of the Anopheles Gambiae mosquito that transmits the parasite to humans and was reported in the journal Science.
Together, the two genetic sequences, along with the human genome that was mapped earlier, give scientists the best means ever of defeating malaria, which claims more than a million lives each year, most of them children aged below five years.
Along with HIV/AIDS and tuberculosis, malaria is one of the biggest infectious killers in the world. “This is the time to put malaria on the agenda. It is a very serious disease,” said Fotis Kafatos, of the European Molecular Laboratory in Heidelberg, Germany, who worked on the mosquito genome.
With 14 chromosomes and 5,279 genes, the malaria genome is one of the smallest sequenced so far. The human genome has about 30,000 genes, the nematode (any parasite or free-living worm) has 18,000 and the Anopheles Gambiae genome has more than 13,000 genes.
But the parasite genome was a major challenge for the scientists because parts of its DNA are very unstable and broke apart as they worked on them.
Researchers from the Sanger Institute, Stanford University in California and the Institute of Genome Research in Maryland collaborated on the six-year, £18.5 million parasite genome project. “The amount of data involved was phenomenal. It was a bit like tearing up half a dozen Bibles, scattering the pieces over a playing field and then trying to put them together again,” Hall said.
Scientists who are working on developing new drugs or a vaccine are already using data from the project which is available on the Internet and have identified potential new drug targets which scientists believe could be available in about five years. “This is an extraordinary moment in the history of science,” said Carlos Morel, of the World Health Organisation (WHO), adding that it opens up a new era in public health.
“At last, the enormous power of modern technology is penetrating the mysteries of an ancient disease, a disease which continues to kill millions,” he added in a statement.
The function of about 60 per cent of the genes is unknown but the genome gives researchers an insight into the parasite’s metabolism, how drug resistance occurs and how to develop new weapons against malaria.
“The genome contains every possible vaccine target and every possible drug target. It is not going to be instantly possible to say where they are but we are giving scientists the tools they need to find them,” said Hall. “We have presented them with the haystack and they have to go and find the needle.”
Despite efforts to eradicate malaria, more people are infected with the parasite in Africa than ever before. According to the WHO, malaria infects 300 million worldwide every year.
The parasite has become resistant to the most common anti-malarial drugs and mosquitoes, which carry it, have developed defences against chemical pesticides.
Plasmodium falciparum is only transmitted by the female mosquito. The parasite moves into the salivary glands of the mosquito and is injected into a human host. It travels through the human bloodstream to the liver where it invades cells, transforms into spores and replicates. The spores are released into the bloodstream where they attack and destroy red blood cells.
“This represents a quantum leap in our understanding of malaria,” said Professor Chris Newbold of Oxford University in England. “The challenge to researchers worldwide is to use the genome sequence in imaginative and innovative ways and ensure that the efforts of the teams from both sides of the Atlantic are rewarded with new ways of tackling the disease.”