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Scientists Created Mosquitoes That Cannot Transmit Malaria
#1
One of the most common and most effective ways to fight the spread of malaria is to control mosquitoes that carry them from one man to another. Unfortunately, this way of fighting turned out to be ineffective as the epidemic of malaria can not be fully controlled. Spraying mosquitoes in the past few years has been less effective because the mosquitoes quickly developed immunity to pesticides. A similar process occurs with the very parasite that causes malaria, which repeatedly developed resistance to various drugs that came from science labs.

But it is possible that science finally has a solution that does not mean the destruction of large populations of mosquitoes, the carriers of malaria, according to Ars Technica. In fact, several years ago began testing in the wilderness, during which the mosquitoes that transmitted dengue fever were infected with a special type of bacteria that prevents the spread of parasite. In a recently published study, a team of scientists published almost sensational results of long-term experiments – they were able to create genetically modified mosquitoes, which, even if they pick up the parasites of malaria, are not able to transmit it to humans. Very simply put: scientists "forced" the Mosquitoes to eject specific antibodies that destroy the parasites that cause human malaria, every time they feed on human blood.

Malaria Parasite Camouflage

Various antibodies and vaccines in the past have proven to be fairly ineffective methods of treatment and prevention of the spread of epidemic malaria. Vaccines have been indeed ineffective because the Plasmodium falciparum, a parasite that causes malaria, showed remarkable ability to develop resistance to almost every vaccine that scientists have tried to develop. This parasite rapidly develops immunity to vaccines, completely changing the proteins that are found on its surface, and all this in order to "confuse" the antibodies. This method of parasite camouflage is possible only after the Plasmodium falciparum has already reached the body of the host.

Antibodies That Attack The Parasites of Malaria

Mosquitoes, on the other hand, have no immune system based on the antibodies like it is the case in humans, which means that the parasite does not have to use all sorts of tricks while in the body of mosquito. For of this reason, scientists have managed to create the special type of antibody that recognizes the structure of proteins of malaria-causing parasite, and is specific for life stage in which the parasite is, while his host is a mosquito.

Antibodies that attack the parasites of malaria are often complex combination of four proteins (two heavy and two light chains). To avoid a rather laborious process of inserting a variety of genes for the entire combination of four proteins that make antibodies, researchers have developed a compact version of the antibody, which contains only one gene with combined heavy and light chains. After this, scientists inserted two genes that encourage compact development of antibodies in the special places of mosquito genome. To limit the impact of antibodies to the mosquitoes, the researchers ensured that the antibody genes activated only after a mosquito ate his first meal and came in contact with the bloodstream of the victim.

No Risk for Mosquito Population

As for the risk of this genetic modification of mosquitoes will harm them, scientists claimed tests have found that fear misplaced. For female mosquito, genes with antibodies had absolutely no effect, and the males were with minimally shortened lifespan. It is important to note that this shortened life span in no way affects the reduction of mosquito population, since the genetically modified mosquitoes can easily experience a period of sexual maturity. So, the new genes didn’t practically do anything bad to mosquitoes, and those are definitely good news for scientists.

If it is to believe the results of this study, scientists have finally succeeded. To use a metaphor, from the malaria mosquito they managed to create a hotel in which the parasite can check-in, but has no way to check-out. Once Plasmodium falciparum enters the body of mosquito, it must find a way to get the salivary glands in order to be spread to other organisms. Specific genes inserted into the genome of mosquitoes were able to prevent this migration, and in this way they practically stopped from being an important link in the chain of spread of epidemic malaria.
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#2
Another interesting way malaria cannot be transmitted

There is another “natural” way, or condition which prevents the spreading of Malaria – it is the sickle-cell disease!

Sickle-cell anemia is congenital disease characterized by abnormal blood cells having a crescent shape. This is due to the abnormal hemoglobin called sickle hemoglobin (also known as hemoglobin S.), which causes the change in the cell’s shape. Sickle cells are sticky and not as elastic as normal red blood cells, making their travel through the blood vessels a lot harder. They often block the blood flow, preventing the blood to come to the limbs and organs, which can cause organ damage and pain.

On the molecular level, the difference between the normal and sickle-cell hemoglobin is only in one amino acid. This change occurs in the β-globin chain; namely, hydrophilic glutamic acid on the sixth position gets replaced with hydrophobic valine. It is important to mention that there are actually two mutation sites in the final protein, since mutation happens in one beta subunit, but hemoglobin has two of these (and two alpha subunits).

After the hemoglobin is deoxygenated, a small hydrophobic patch appears on the surface which is a good contact point for more hemoglobin proteins, making them stick together and thus form a chain. This polymerized hemoglobin distorts the normal shape of red blood cells. The condition is not so serious if a patient is heterozygous, having both normal and sickle-cell hemoglobin proteins, since the normal hemoglobin prevents the polymerization of the sickle-cell hemoglobin. The real problem occurs when a person is homozygous, resulting in lysed red blood cells.

There is an interesting „side effect“ of sickle-cell disease, however. Persons with this disease (even heterozygotes) are resistant to one type of malaria. This is due to the fact that malaria parasites attack red blood cells. However, the body senses that sickled cells are defective, and it destroys them by sending them to the spleen (parasites die with them). Moreover, sickle cell is deformed in shape having more pores which leads to the excess leakage of nutrients outside of the cell, making the environment unfriendly for the parasite.

This is an interesting way how one negative thing can result in another positive one.
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#3
This is a very interesting topic, especially for the tropical regions
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