THURSDAY, SEPTEMBER 29, 2016

Mosquito-borne virus immune avoidance mechanism may lead to treatment

The University of Pittsburgh Center for Vaccine Research said on Wednesday that the discovery of an immune suppresing mechanism used by mosquito-borne viruses could help in the development of vaccines and treatment for eastern equine encephalitis.


The study was funded by the National Institutes of Health, and results were published in the health journal Nature.


"Anytime you understand how a virus causes a disease, you can find ways to interrupt that process," senior author William Klimstra, associate professor at Pitt's Center for Vaccine Research, said. "And this discovery is particularly exciting because it is the first time that anyone has shown a virus using this particular strategy to evade its host's immune system and exacerbate disease progression."


Scientists said the discovery of the immune system suppression used by the virus might be helpful in developing vaccines and treatments for other diseases, such as West Nile virus, dengue, rhinovirus and SARS.


Klimstra said equine encephalitis virus has developed a binding site that bonds with the ribonucleic acid in the cells of the organism it invaded. When the virus is bonded to the RNA, it is restricted from replicating, which restricts an immune system from detecting the virus.


Because the immune system experiences a delay in recognizing the virus, the disease is able to spread inside the body and cause overwhelming disease. EEEV causes brain swelling, and symptoms include headache, high fever, chills and vomiting, which quickly become disorientation, seizures and coma. The disease is rare and treatment is not available.


Klimstra and his team used a mutant version of EEEV that helped them discover the binding site.


"Viruses are constantly evolving and changing," Klimstra said. "However, the genetic sequence that allows EEEV to bind to our microRNA has persisted. We find it in samples from the 1950s, which indicates tremendous evolutionary selection pressure to maintain this mechanism. Ultimately, these results suggest that the mutant virus could be used as an EEEV vaccine and that microRNA blockers could have potential for use as a therapeutic treatment for EEEV-infected patients who currently can be treated only with supportive care."

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