Cytomegalovirus, CMV, is thought to be one of the causes of the immune system's dysfunction with age. It is a persistent herpesvirus: it cannot be effectively cleared from the body, but the immune system devotes ever more of its limited capacity to fighting it, reducing its ability to deal with new threads. This is characterized by an increase in CMV-focused memory cells. Simply getting rid of CMV, if we could, wouldn't reverse this harm: that would require a treatment along the lines of selectively destroying the CMV-specialized cells to free up space.
Infection with human cytomegalovirus (CMV) affects the function and composition of the immune system during ageing. In addition to the presence of the pathogen, the strength of the immune response, as measured by the anti-CMV IgG titre, has a significant effect on age-related pathogenesis. High anti-CMV IgG titres have been associated with increased mortality and functional impairment in the elderly. In this study, we were interested in identifying the molecular mechanisms that are associated with the strength of the anti-CMV response by examining the gene expression profiles that are associated with the level of the anti-CMV IgG titre.
The level of the anti-CMV IgG titre is associated with the expression level of 663 transcripts in nonagenarians. These transcripts and their corresponding pathways are, for the most part, associated with metabolic functions, cell development and proliferation and other basic cellular functions. However, no prominent associations with the immune system were found, and no associated transcripts were found in young controls.
The lack of defence pathways associated with the strength of the anti-CMV response can indicate that the compromised immune system can no longer defend itself against the CMV infection. Our data imply that the association between high anti-CMV IgG titres and increased mortality and frailty is mediated by basic cellular processes.