Prevalence and loads of torquetenovirus (TTV) in the European MARK-AGE Study population.

Torquetenovirus (TTV) viremia has been associated with increased mortality risk in the elderly population. This work aims to investigate TTV viremia as a potential biomarker of immunosenescence. We compared levels of circulating TTV in 1,813 participants of the MARK-AGE project, including human models of delayed (offspring of centenarians - GO) and premature (Down syndrome - DS) immunosenescence. The TTV load was positively associated with age, CMV antibody levels and the Cu/Zn ratio, and negatively associated with platelets, total cholesterol and total IgM. TTV viremia was highest in DS and lowest in GO, with intermediate levels in the SGO (spouses of GO) and RASIG (randomly recruited age-stratified individuals from the general population) populations. In the RASIG population, TTV DNA loads showed a slight negative association with CD3+T-cells and CD4+T-cells. Finally, males with >/=4log TTV copies/ml had a higher risk of having a CD4/CD8 ratio /=4log copies/ml, thus promoting an immune risk phenotype.