Sunday, 22 April 2012

Sea Cucumber aids in malaria fight

It’s an infection that kills 1 to 2 million people each year. With about 40% of the human population at risk of becoming infected and more than 300 million seriously infected every year, malaria is among one of the world’s worst diseases (Krishenbaum S. 2007, Yoshida S. et al 2007, ScienceDaily 2007.

Malaria is caused by protest parasites belonging to the genus Plasmodium. They survive in bodies of mosquitoes and mammals, with five species that are able to infect humans (WebMD 2012, MedicineNet 2011). Why has there been no vaccine or effective treatment? Well the malaria parasite is not your typical parasite, they are known to often build up unwanted resistance to current anti-malarial medications leading to the emergence of strains of resistant Plasmodium (Yoshida S. et al 2007). The malaria parasite also, once inside our body, hides within human liver and blood cells where it becomes undetected by our immune system therefore which has been even more difficult to treat(MittleIstadt K. 2008, Tennen R. 2008). This is why it has been essential for researchers to constantly seek to develop different methods to treat this disease.

In an infected mosquito, the parasite’s sex cells within the human blood travels into the gut and fertilises itself creating offspring called ookinetes (Krishenbaum S. 2007, Tennen R. 2008, MittleIstadt K. 2008, ScienceDaily 2007, Yoshida S. et al 2007). These then create daughter cells called sporozoites which make their way to the mosquito’s salivary glands where they wait for the mosquito to feed.  When the mosquito feeds on human blood again the sporozoites are carried into the human blood via infected saliva(Krishenbaum S. 2007, Tennen R. 2008, MittleIstadt K. 2008, ScienceDaily 2007, Yoshida S. et al 2007).. The sporozoites then get transported into the liver where it invades cells and multiply, all the while hiding from the person’s immune system(Krishenbaum S. 2007, Tennen R. 2008, MittleIstadt K. 2008, ScienceDaily 2007, Yoshida S. et al 2007).

A team of international researchers have developed a transgenic  mosquito to aid in the fight against malaria. They fused a gene from the sea cucumber, Cucumaria echinata, into the mosquito, encoding for a protein called Lectin(CEL-III), known to be toxic to developing parasites. This created a mosquito that whenever fed on human blood would release Lectin into their stomach and therefore impair the development and growth of about 95%(MittleIstadt K. 2008,ScienceDaily 2007, Yoshida S. et al 2007). This has been a big step towards the future goal of maybe one day genetically engineer mosquitoes so that the malaria parasite cannot develop inside them stated one of the involved researchers, Professor Bob Sinden from Imperial College London’s department of Life Sciences(ScienceDaily 2007). Unfortunately, the lethal protein does not kill all parasites within mosquitoes and also does not stop the cycle of infection from mosquito to humans(ScienceDaily 2007). The team also tested whether these GM mosquitoes would “over-take” non-transgentic mosquitoes to see if they would be able to compete with them in nature (Yoshida S. et al 2007). The results showed that they would be able to over-take the non-transgenic mosquitoes (Yoshida S. et al 2007).

With  1 to 2 million dying each year, the malaria parasite is one of the world’s worst health problems. A lack of effective vaccines and treatments because of the nature of the malaria parasite has kept scientists struggling to constantly develop new methods of treating this parasite but the fusing of sea  cucumber protein, Lectin into mosquitoes to inhibit the parasite’s development in mosquitoes has deemed a big step in the fight against this deadly disease. 

References:

-          Krishenbaum S. 2007, The Sea Cucumber: Super Hero or Fine Cuisine?, viewed 10 March 2012, <http://blogs.discovermagazine.com/intersection/2007/12/21/the-sea-cucumber-super-hero-or-fine-cuisine/>
-          MedicineNet 2011, Definition of Plasmodium, viewed 17 March 2012, < http://www.medterms.com/script/main/art.asp?articlekey=4939>
      MittleIstadt K. 2008, Mosquito and cucumber salad anyone, viewed 10 March 2012, <http://www.firstscience.com/home/articles/humans/mosquito-and-cucumber-salad-anyone-page-1-1_45364.html>
-          ScienceDaily 2007, Sea cucumber protein used to inhibit development of malaria parasite, viewed 10 March 2012, < http://www.sciencedaily.com/releases/2007/12/071220203704.htm>
-          WebMD 2012, Malaria viewed 17 March 2012, <http://www.emedicinehealth.com/malaria/article_em.htm>
-           WHO 2012, Drug resistance: malaria, viewed 17 March 2012, <http://www.who.int/drugresistance/malaria/en/>
-          Yoshida S. et al 2007, Hemolytic C-Type Lectin CEL-III from Sea Cucumber Expressed in Transgenic Mosquitoes Impairs Malaria Parasite Development, PLoS Pathog 3, viewed 8 March 2012, <http://www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.0030192>

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