Mon Oct 20, 5:32 PM ET
Little monkeys called marmosets may help scientists discover whether viruses cause multiple sclerosis, researchers reported on Monday.
They said the animals developed a disease similar to MS in humans after being infected with a common herpes virus, one of several suspected of causing the debilitating illness.
"In the infected marmosets, HHV6 infection appears to produce an inflammatory disorder in the central nervous system almost identical to MS in humans," Dr. Claude Genain of the University of California San Francisco, who led the study, said in a statement.
Multiple sclerosis, which affects an estimated 1 million people worldwide, is considered to be an autoimmune disease, caused when the body mistakenly attacks healthy nerve cells.
Its symptoms vary but it can cause weakness and paralysis.
Many experts believe that somehow a virus triggers the mistaken immune system reaction that causes MS.
"Because common viruses such as measles, varicella zoster (chicken pox), Epstein-Barr and others infect virtually everyone during their childhood without adverse consequences, it is difficult to prove a relationship between these viruses and MS," said Genain.
Having an animal model of the disease could help sort out possible causes, Genain told a meeting of the American Neurological Association in San Francisco.
"This is an unprecedented opportunity to understand how infection with a common human virus could lead to MS in a model system that resembles young humans," said Genain.
Marmosets can develop an MS-like illness called experimental allergic encephalomyelitis.
Genain's team found that HHV6, one of several herpes viruses that infect people, causes this encephalomyelitis in the monkeys.
HHV6 infects human immune cells known as T lymphocytes. It may cause childhood roseola or exanthem subitum, which can be marked by fever and a distinct rash.
It is also suspected as a possible cause of chronic fatigue syndrome.
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