Malaria / Every minute two children die in Africa from the disease; Every year about 500 million are infected
Tamara Traubman
The genomes of two of the creatures that cause the greatest human suffering in the world are being deciphered. This is a parasite that causes malaria and the Anopheles mosquito, which transmits the disease to humans. Some public health experts said that the new genomes are the most important that have been deciphered so far - from the point of view of the health of the world's population. According to Dr. Anthony Posey, director of the US National Institute of Allergy and Infectious Diseases, "the new data obtained from the decoding of the genomes offer an unprecedented opportunity to the scientific community and public health professionals in the fight against malaria, a disease that exacts a huge toll on humanity."
Every minute, two children die from malaria. Almost all of these children, like most people who contract the disease, live in African countries south of the Sahara desert. Although the disease does not receive much attention in the West, its dimensions exceed the dimensions of the AIDS epidemic. Every year about 500 million more people become infected with malaria.
Children are the main victims of the disease (half of the African children who die as a result of the disease die before the age of five). Even those who survived the disease, continue to suffer from anemia and a weakened immune system, which exposes them to infection and death from other deadly diseases.
Malaria was once widespread in large parts of the world, but in the 50s and 60s, operations by the United Nations' World Health Organization succeeded in eradicating it from European countries and the United States. Today, it remains a disease of the poor world. In an era in which health is defined in international treaties as a human right, many of the sick are so poor that they cannot afford protection and treatment. At the same time, a new threat has also emerged to existing and relatively inexpensive treatments: existing drugs and insecticides are rapidly losing their effectiveness, because the malaria parasite and Anopheles are developing resistance to them.
The malaria parasite genome project included 150 researchers, led by Malcolm Gardner from the Genomics Research Institute in the US and researchers from the British Sanger Institute and the Stanford Center for Genomic Technologies in the US. The genome of the Anopheles mosquito was decoded by researchers from the US, France, Israel, Spain, Germany, Britain, Russia, Italy and Greece. The work on the mosquito was led by Dr. Robert Holt from the American company "Sella Genomics", which received a grant from the World Health Organization to decode the genome. This company decoded its own version of the human genome about two years ago. Usually, the company keeps the genetic data for itself and sells it to pharmaceutical companies and universities. But this time it has published the data in full and they are available for free on a website called "GenBank". The information about the genomes, accompanied by new findings about them, will be published today in the scientific journals Nature and Science.
The researchers deciphered the genome of the most common and dangerous type of malaria parasite - Plasmodium falciparum - and the Anopheles gambiae mosquito, which serves as a carrier that transmits the parasite in Africa. In deciphering the genomes, the researchers identified the order of the DNA units of these creatures. This sequence is divided into genes, which contain recipes for making proteins. The proteins make up the body (including hairs and internal organs) and activate the activity of the cells, some of them may be toxins that cause diseases. Others are needed, for example, for the operation of the digestive system.
Dr. Ron Waids, a geneticist from Bar Ilan University and a partner in the team that deciphered the Anopheles genome, says that the new data will serve as a "springboard for the development of disease control measures." Initial studies of the data, which began to be published online in the spring, located, according to Dr. Waids, "the special genes Only for the parasite, which provide new targets for the development of methods that will harm only it and will not harm other insects."
Particularly interesting genes were discovered by Prof. Lawrence Zwiebel of Vanderbilt University and his colleagues. The team discovered 79 genes, which are apparently involved in the mosquito's sense of smell, and 72 genes involved in its sense of taste. According to Prof. Rachel Galon, an expert on disease-carrying insects from the Hebrew University, the importance of these genes stems from the fact that "Anopheles has a clear preference for humans, and it detects human blood through its sense of smell." According to her, these genes could help in the development of a genetically modified mosquito, which would make it behave like its relative - another species of Anopheles - and disrupt its sense of smell, so that it would want to bite animals and not humans. "In this way, it will cease to be a mosquito that transmits malaria and other diseases," says Prof. Galon. "The idea to engineer a mosquito that would not transmit the parasite to humans was first proposed 18 years ago by Lou Miller of the US National Institutes of Health. This idea gave a huge boost to the entire field of mosquito genetics."
Today, several teams in the world are trying to develop genetically modified mosquitoes - one such mosquito, in which the development of the parasite is stopped before it is sufficient to transmit it to humans, already exists. "The idea looks excellent," adds Prof. Galon, "but many problems still remain. Ecologists say that before releasing such a creature into the wild, one must make sure that it will not harm the environment. Before that, they will have to make sure that it has genetic superiority over other mosquitoes, which will allow it to take over on the existing mosquito population."
Prof. Shola Michaeli, an expert on the molecular aspects of parasites from Bar Ilan University, says: "The next challenge in malaria parasite research will be to develop new approaches that will allow learning about the newly discovered genes, to find out what their role is and whether they belong to the process that causes the disease." She mentions that despite the decoding of the genome, "the role of 60% of the genes of the marlia parasite is still unknown, because they have no parallels in any other known creature. There is still a lot of work to be done."
Do the new genomes herald the beginning of malaria eradication, or at least the reduction of its scope to a significant extent? On the one hand, Prof. Rachel Galon from the Hebrew University says that there is enormous promise in the publication of genomes. The genetic information may help in the development of drugs, new vaccines and improved methods to control the Anopheles mosquito. On the other hand, says Prof. Galon, there is still the question of whether the pharmaceutical companies will "pick up the gauntlet" and develop the technologies necessary to control the epidemic.
"The companies know," says Prof. Galon, "that in the case of malaria - it's simply not a market that can pay for medicines."
Tamara Traubman
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