Persistent cytomegalovirus (CMV) infection is thought to cause a sizable amount of the age-related decline of the immune system. Latent infection by this sort of herpesvirus causes few to no immediate and obvious symptoms in the vast majority of individuals, but the virus cannot be permanently cleared by the immune system. Over time ever more T cells of the adaptive immune system become uselessly specialized to CMV, unavailable for other tasks. Coupled with the much reduced pace of creation of new T cells in later life, this results in an increasingly dysfunctional immune system.
Researchers here point to one specific consequence of the accumulation of a problematic class of T cell noted to occur with aging, increased risk of cardiovascular disease, and present evidence to show that this accumulation occurs because of persistent CMV infection. All told, the evidence for CMV to be a major issue, a slow corrosion of immune function and health, is quite compelling. What to do about it? The most effective approach might not be to tackle CMV directly, but rather to clear out and replace the problem immune cells via some form of targeted cell destruction