Researchers map how measles virus spreads in human brain

Mayo Clinic researchers mapped how the measles virus mutated and spread in the brain of a person who succumbed to a rare, lethal brain disease. New cases of this disease, which is a complication of the measles virus, may occur as measles reemerges among the unvaccinated, say researchers.

Using the latest tools in genetic sequencing, researchers at Mayo Clinic reconstructed how a collective of viral genomes colonized a human brain. The virus acquired distinct mutations that drove the spread of the virus from the frontal cortex outward.

"Our study provides compelling data that shows how viral RNA mutated and spread throughout a human organ — the brain, in this case," says Roberto Cattaneo, Ph.D. a Mayo Clinic virologist who is a co-lead author on a new PLOS Pathogens study. "Our discoveries will help studying and understanding how other viruses persist and adapt to the human brain, causing disease. This knowledge may facilitate the generation of effective antiviral drugs."

He first began to study the measles virus about 40 years ago and was fascinated by the rare, lethal brain disease called subacute sclerosing panencephalitis (SSPE), which occurs in about 1 in every 10,000 measles cases. It can take about five to 10 years after the initial infection for the measles virus to mutate and spread throughout the brain. Symptoms of this progressive neurological disease include memory loss, seizures and immobility. Dr. Cattaneo studied SSPE for several years until the lethal disease nearly disappeared as more people were vaccinated against measles.

The researchers discovered that, after the measles virus entered the brain, its genome — the complete set of genetic material for the virus — began to change in harmful ways. The genome replicated, creating other genomes that were slightly different. Then, these genomes replicated again — resulting in more genomes that were each a little different as well. The virus did this multiple times, creating a population of varied genomes.

"In this population, two specific genomes had a combination of characteristics that worked together to promote virus spread from the initial location of the infection — the frontal cortex of the brain — out to colonize the entire organ," says Dr. Cattaneo.

Reference: Researchers map how measles virus spreads in human brain, MAYO CLINIC; PLoS Pathogens