Doctors have traced the mechanism of brain hijacking by the mutated measles virus
A postmortem examination of tissue from an American man who died from PSPE, a rare but dangerous complication of measles, has helped to reconstruct a picture of how the virus spreads in the human brain. Medics have warned that the deadly disease could increase in frequency amid a rise in the number of people unvaccinated against measles.
In a paper published in the journal PLOS Pathogens, experts from the Mayo Clinic and other medical research centers in the United States studied brain samples taken after an autopsy of a patient from the United States. He died in 2010 from subacute sclerosing panencephalitis (PSPE) at the age of 24.
PSPE, a progressive neurodegenerative disease of the central nervous system, is caused by the measles virus. It develops in an average of one or two patients out of 10,000 who have had measles. PSPE is considered a slow viral infection. Primary infection is followed by an asymptomatic period that usually lasts 5-10 years, but can range from one month to 27 years in some cases. The mutated measles virus spreads through the brain, causing first subtle intellectual and mental impairment and then deterioration of sensory and motor functions, eventually ending in death.
In recent years, outbreaks of measles infection have become more frequent around the world, and health professionals attribute this to the rise of anti-vaccination movements and missed vaccinations. According to the U.S. Centers for Disease Control and Prevention, the Covid-19 pandemic caused millions of children to miss scheduled measles vaccinations. This turned into an 18% increase in cases and 43% increase in measles deaths in 2022 compared to 2021. Doctors fear that subacute sclerosing panencephalitis, which almost disappeared during the years of more mass measles vaccination, could now also resurface.
A team of U.S. scientists, including Mayo Clinic virologist Roberto Cattaneo, who studies measles and PSPE, is using modern biomedical technology to try to learn more about the deadly disease. Researchers conducted genetic sequencing of 15 samples from different parts of the brain of a patient who had measles as a child and died of PSPE as an adult.
RNA analysis of the measles virus showed that once it entered the brain, its genome - the virus' complete set of genetic instructions - began to change pathologically. When the mutated genome replicated, it generated other genomes, again slightly different from the original genome. The process repeated itself many times, creating subpopulations of measles virus with different genomes.
The authors of the paper identified two major types of measles virus genome that were present in all samples studied. According to Dr. Cattaneo, the combination of characteristics of the mutant genomes collectively contributed to the spread of the virus from the primary site of infection - the frontal cortex - throughout the brain.
The scientists intend to continue the research. At the next stages, they want to understand how certain mutations favor the growth of the virus in brain tissue. For this purpose, the authors are going to use cultured brain cells and brain organoids created with their help. The researchers expect that their findings will help to develop more effective antiviral drugs.