01 June 2013 Bugs Help Out Bacteria might seem unlikely allies when fighting disease, yet they could hold the key to controlling malaria. This deadly tropical illness is caused by Plasmodium parasites, transmitted to humans via mosquito bites. However, mosquitoes can be made somewhat resistant to the parasite, by infecting them with Wolbachia bacteria, which block the parasite’s development. Infected individuals thus carry, and transmit, far fewer parasites. Researchers have recently succeeded in infecting Anopheles stephensi, a species largely responsible for malarial transmission in the Middle East and Asia; the picture reveals the presence of Wolbachia (stained green) in a mosquito’s ovaries. Infected females pass Wolbachia on to their offspring, and infected males only breed successfully with infected females, so parasite resistance quickly spreads within the population. A similar technique, applied to mosquitoes transmitting the virus responsible for dengue fever, has yielded promising results, raising hopes that this approach might provide solutions for malaria too. Written by Emmanuelle Briolat — Zhiyong Xi Michigan State University, USA Reprinted with permission from AAAS. Published in Science 340(6133): 748-751
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01 June 2013

Bugs Help Out

Bacteria might seem unlikely allies when fighting disease, yet they could hold the key to controlling malaria. This deadly tropical illness is caused by Plasmodium parasites, transmitted to humans via mosquito bites. However, mosquitoes can be made somewhat resistant to the parasite, by infecting them with Wolbachia bacteria, which block the parasite’s development. Infected individuals thus carry, and transmit, far fewer parasites. Researchers have recently succeeded in infecting Anopheles stephensi, a species largely responsible for malarial transmission in the Middle East and Asia; the picture reveals the presence of Wolbachia (stained green) in a mosquito’s ovaries. Infected females pass Wolbachia on to their offspring, and infected males only breed successfully with infected females, so parasite resistance quickly spreads within the population. A similar technique, applied to mosquitoes transmitting the virus responsible for dengue fever, has yielded promising results, raising hopes that this approach might provide solutions for malaria too.

Written by Emmanuelle Briolat

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Source: bpod.mrc.ac.uk

Neglected Hide-and-Seek Sneaking into our bodies is only the first step for parasites. They must then evade the numerous defence mechanisms that seek to destroy them. But if they can find a safe haven to multiply in, before launching a full-scale attack, they can increase their chances of success. And where better to do this than in the very white blood cells that are hunting them? Normally this strategy would end in certain destruction, but parasites containing Chagas disease possess a protein that disrupts white blood cells’ normal defences. This image shows that normal response, as an alarm molecule (stained green and yellow) moves from the main white blood cell body into the control centre called the nucleus (stained red), where it triggers the immune response. It’s the ability to block this process that allows the parasites to establish the disease, which infects about 10 million people throughout Latin America annually. Written by Jan Piotrowski — Patricia Doyle University of California, San Francisco, USA Image originally published under Creative Commons Attribution License Published in PLOS Pathogens 7(9): e1002139
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Neglected Hide-and-Seek

Sneaking into our bodies is only the first step for parasites. They must then evade the numerous defence mechanisms that seek to destroy them. But if they can find a safe haven to multiply in, before launching a full-scale attack, they can increase their chances of success. And where better to do this than in the very white blood cells that are hunting them? Normally this strategy would end in certain destruction, but parasites containing Chagas disease possess a protein that disrupts white blood cells’ normal defences. This image shows that normal response, as an alarm molecule (stained green and yellow) moves from the main white blood cell body into the control centre called the nucleus (stained red), where it triggers the immune response. It’s the ability to block this process that allows the parasites to establish the disease, which infects about 10 million people throughout Latin America annually.

Written by Jan Piotrowski

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Source: bpod.mrc.ac.uk

Unwanted Visitor Parasites, in all their forms, artfully exploit their unwitting host. Protozoan parasites, like malaria-causing Plasmodium, have evolved clever ways to hoodwink their host.Theileria is similar to Plasmodium but infects cattle and is spread by ticks rather than mosquitoes. Here, a white blood cell infected with Theileria (labelled green) is dividing into two daughter cells and the parasite has adopted a cunning disguise to get itself copied in the process. By covering itself in one of the host’s own proteins Theileria is pulled to opposite ends of the cell by the spindle (stained red) along with the dividing host DNA (stained blue). When the daughter cells split both will be infected and the parasite quickly spreads throughout the blood in this way. Scientists hope that understanding exactly how these tiny tricksters operate will inspire new ways to stop them. Written by Emma Stoye — Dirk Dobbelaere University of Bern, Switzerland Originally published under Creative Commons (CC-BY 2.0) Published in PLOS Biology 8(9): e1000499
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Unwanted Visitor

Parasites, in all their forms, artfully exploit their unwitting host. Protozoan parasites, like malaria-causing Plasmodium, have evolved clever ways to hoodwink their host.Theileria is similar to Plasmodium but infects cattle and is spread by ticks rather than mosquitoes. Here, a white blood cell infected with Theileria (labelled green) is dividing into two daughter cells and the parasite has adopted a cunning disguise to get itself copied in the process. By covering itself in one of the host’s own proteins Theileria is pulled to opposite ends of the cell by the spindle (stained red) along with the dividing host DNA (stained blue). When the daughter cells split both will be infected and the parasite quickly spreads throughout the blood in this way. Scientists hope that understanding exactly how these tiny tricksters operate will inspire new ways to stop them.

Written by Emma Stoye

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Source: bpod.mrc.ac.uk

Hair Trigger Humans have about the same number of hair follicles (seen here in cross-section) as would be expected of an ape of our size, but we grow only fine hair over most of our body. Why we evolved with very little thick hair is a matter of debate. One theory is that skin parasites were a trigger – coarsely hirsute mammals provide them with a hiding place, while our more delicate down actually makes their detection easier. Researchers tested this idea by placing bed bugs on the arms of volunteers and measuring the time they took to bite. The more fine hair on the volunteer’s arm, the longer the bugs searched before feeding on blood, making it more likely they would be detected and scratched. It seems that a good covering of fine hair is optimal, reducing risks associated with infected bites. Written by Mick Warwicker — Michelle Peckham University of Leeds Image courtesy Centre for Bioscience, the Higher Education Academy, ImageBank
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Hair Trigger

Humans have about the same number of hair follicles (seen here in cross-section) as would be expected of an ape of our size, but we grow only fine hair over most of our body. Why we evolved with very little thick hair is a matter of debate. One theory is that skin parasites were a trigger – coarsely hirsute mammals provide them with a hiding place, while our more delicate down actually makes their detection easier. Researchers tested this idea by placing bed bugs on the arms of volunteers and measuring the time they took to bite. The more fine hair on the volunteer’s arm, the longer the bugs searched before feeding on blood, making it more likely they would be detected and scratched. It seems that a good covering of fine hair is optimal, reducing risks associated with infected bites.

Written by Mick Warwicker

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Source: bpod.mrc.ac.uk