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       #Post#: 1224--------------------------------------------------
       JC virus carries a mutation in MS patients that amplifies PML
       By: agate Date: May 24, 2016, 6:52 pm
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       From Multiple Sclerosis News Today, May 24, 2016:
       [quote]JC Virus Carries a Mutation in MS Patients That Amplifies
       Brain Disease Known as PML
       Magdalena Kegel
       A mutation in a mouse model of the John Cunningham (JC) virus,
       which causes progressive multifocal leukoencephalopathy (PML),
       allows the virus to evade the host immune responses in people
       with multiple sclerosis (MS), according to a study into the
       mechanisms of PML.
       Infection with the JC virus most often passes unnoticed in
       healthy adults. For reasons still eluding scientists, however,
       MS patients treated with natalizumab (Tysabri), as well as
       patients with other autoimmune conditions and cancers treated
       with certain immunosuppressive drugs, are at increased risk of
       developing the brain disease.
       “Nobody comes away unscathed from PML — you either die or you’re
       left with a lifelong searing neurological defect,” Aron E.
       Lukacher, chair and professor of microbiology and immunology at
       Penn State College of Medicine, said in a press release.
       “Because we don’t know how the drugs cause the JC virus to
       amplify from a silent infection, we really have no way of
       controlling it.”
       Earlier research noted that JC virus isolated from patients with
       PML was mutated. The mutation, present as a change of a single
       amino acid, affects the part of the virus shell that allow it to
       dock into and infect human cells. Scientists demonstrated that
       the mutation alters the capacity of the virus to infect certain
       tissues, but until now they did not know whether it also had an
       impact on immune responses to the virus.
       The study, “Type I Interferons Regulate the Magnitude and
       Functionality of Mouse Polyomavirus-Specific CD8 T Cells in a
       Virus Strain-Dependent Manner,” published in the Journal of
       Virology, set out to explore this crucial question.
       Investigating mice with a mouse variant of the JC virus, the
       research team indeed found that when the mutation was present,
       immune T-cell responses were not as pronounced.
       “We found that mouse polyomaviruses with a single amino acid
       change in their shell elicit a very different magnitude and
       quality of the T cell response that is needed to control the
       infection,” Dr. Lukacher said.
       Researchers also found that the reduced T-cell activation was a
       result of altered type 1 interferon responses, immune factors
       normally activating T-cells.
       “We need to find ways to improve the T cell responses in
       patients on these therapies,” concluded Dr. Lukacher.[/quote]
       The article can be seen here
  HTML http://multiplesclerosisnewstoday.com/2016/05/24/mutation-in-pml-virus-allows-evasion-of-host-immune-responses-in-ms/.
       The Journal of Virology abstract can be seen here
  HTML http://jvi.asm.org/content/90/10/5187.abstract.
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