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Parasites found to use “Trojan horses” to quell resistance

Nov. 26, 2014
Courtesy of the University of Edinburgh
and World Science staff

Par­a­sites use a “Tro­jan horse”-like trick to sup­press the im­mun­ity of their vic­tims, ac­cord­ing to a study whose au­thors hope it will pave the way for new treat­ments.

The re­search­ers found that par­a­sites can dump ti­ny sealed pack­ages of ge­net­ic ma­te­ri­al in­to their vic­tims’ cells that serve to head off re­talia­t­ion by the vic­tim’s im­mune sys­tem. The pack­ages, known as vesi­cles, mim­ic pack­ages that are pro­duced nat­u­rally in most or­gan­isms for eve­ry­day func­tions such as car­ry­ing nu­tri­ents and chem­i­cal mes­sages among cells. 

The par­a­site uses vesi­cles to hide its ma­te­ri­al in­side a seem­ingly friendly ex­te­ri­or, like the gi­ant horse stat­ue that the an­cient Greeks re­put­edly left as a gift to the city of Troy. This was a trick to sneak Greek sol­dier­s—the stat­ue was full of them—in­to the en­e­my city.

The stu­dy, car­ried out on a par­a­site of mice, showed that the ma­te­ri­al in the pack­ages can in­ter­act with the mouse’s own genes. It ma­ni­pu­lates the cel­l’s ma­chin­ery to keep it from pro­duc­ing im­mun­ity-related molecules.

“We can see for the first time that par­a­sites can use pack­ages to sneak their ma­te­ri­al in­to the cells of oth­er or­gan­isms,” said Amy Buck of the Uni­vers­ity of Ed­in­burgh in the U.K., who led the stu­dy. “We now can de­vel­op ways to tar­get this with im­plica­t­ions for the bil­lions of peo­ple and an­i­mals at risk of in­fec­tious dis­eases and al­ler­gy.” 

The re­search­ers say the find­ing could in­form new strate­gies for treat­ing dis­eases caused by par­a­sit­ic worms, which af­fect hun­dreds of mil­lions of peo­ple and an­i­mals. The find­ings al­so of­fer a pos­si­ble way to treat al­ler­gies, such as hay fever, be­cause the im­mune mech­an­ism that par­a­sites block is al­so linked to al­ler­gic re­ac­tions.

The ge­net­ic ma­te­ri­al from the par­a­sites can al­so be de­tected in hu­man blood, sug­gest­ing that this could be used as a test to de­tect in­fec­tion in peo­ple, the re­search­ers said. On­go­ing stud­ies are look­ing in­to wheth­er oth­er par­a­sites and vi­rus­es use this same strat­e­gy. The study is pub­lished in the jour­nal Na­ture Com­mu­nica­t­ions.


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Parasites use a “Trojan horse”-like trick to suppress the immunity of their victims, according to a study whose authors hope it will pave the way for new treatments. The researchers found that parasites can dump tiny sealed packages of genetic material into their victims’ cells that serve to head off retaliation by the victim’s immune system. The packages, known as vesicles, mimic packages that are produced naturally in most organisms for everyday functions such as carrying nutrients and chemical messages among cells. The parasite uses vesicles to hide its material inside a seemingly friendly exterior, like the giant horse statue that the ancient Greeks reputedly left as a gift to the city of Troy. This was a trick to sneak Greek soldiers—the statue was full of them—into the enemy city. The study, carried out on a parasite of mice, showed that the material in the packages can interact with the mouse’s own genes. It manipulates the cell’s machinery to keep it from producing immunity-related molecules. “We can see for the first time that parasites can use packages to sneak their material into the cells of other organisms,” said Amy Buck of the University of Edinburgh in the U.K., who led the study. “We now can develop ways to target this with implications for the billions of people and animals at risk of infectious diseases and allergy.” Researchers say the finding could inform new strategies for treating diseases caused by parasitic worms, which affect hundreds of millions of people and animals. The findings also offer a possible way to treat allergies, such as hayfever, because the immune mechanism that parasites block is also linked to allergic reactions. The genetic material from the parasites can also be detected in human blood, suggesting that this could be used as a test to detect infection in people, the researchers said. Ongoing studies are looking into whether other parasites and viruses use this same strategy. The study is published in the journal Nature Communications.