Research funded by the USDA’s Agricultural Research Service examined the hypothesis that the passage of some viruses through older hosts may alter the virulence characteristics of the virus.
The investigators, in a study conducted at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston, MA, infected a young group and an old group of mice with a common virus. There were no deaths in the young study group, but 14 percent of the older group died.
When the virus was recovered from the old mice and used to infect another group of young and old mice, 43 percent of the young mice died and 71 percent of the older group died. This indicated to the researchers that the virus had somehow changed to a more virulent state in the older mice. DNA sequencing of the two viruses confirmed that the original virus had undergone mutations in the DNA segment related to virulence during passage in the older mice.
While unsure of the mechanism supporting this mutation, the researchers expressed concern about the implications of their findings given the ageing of the human population and the implications of age-associated viral evolution on public health.
Source:
USDA, ARS Press release