title: Cytomegalovirus persistence and T-cell immunosenescence in people aged fifty and older: A systematic review.
abstract: BACKGROUND
  Immunosenescence is the age-related deterioration of immunocompetence which is reflected in a poorer response to new antigens. This process is characterized by decreases in naïve T cells and increases in memory T cells. The highly prevalent β-herpesvirus cytomegalovirus (CMV) is thought to enhance T-cell immunosenescence. The aim of this study was to perform a systematic review on the current evidence regarding the relation between CMV-infection and immunosenescence in Western people aged fifty years and older.
  
  
  METHODS
  Studies that investigated the relation between CMV infection and immune parameters in Western people aged 50 years and older were eligible for inclusion. No restrictions were placed on study type. This article focuses on the relation between CMV infections as measured by serology and T cell subsets. A narrative approach to data synthesis was applied.
  
  
  RESULTS
  In the majority of included studies higher levels of Effector Memory (EM) and TEMRA (Effector Memory T cells re-expressing CD45RA) cells were found in the CD4+ and the CD8+ T cell pools in CMV-seropositive elderly compared to CMV-seronegative elderly. No clear evidence was found for lower levels of naïve T cells in CMV-seropositive elderly compared to CMV-seronegative elderly. The total CD8+ T cell pool appeared to be larger in CMV-seropositive elderly in three out of four studies, while the total CD4+ T cell pool appeared to be smaller in CMV-seropositive elderly in two out of four studies.
  
  
  CONCLUSIONS
  CMV seems to enhance immunosenescence based on the high levels of the highly differentiated EM and TEMRA cells in the CD8+ and CD4+ T cell pools. The relation of the shifts within the T cell compartments in CMV-seropositive elderly in relation to susceptibility to infectious diseases remains to be investigated.
authors.affiliation: National Institute of Public Health and the Environment (RIVM), Centre for Infectious Disease Control, Centre Infectious Diseases, Epidemiology and Surveillance, Antonie van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands. Electronic address: marlies.weltevrede@rivm.nl.
authors.forename: Marlies
authors.initials: M
authors.lastname: Weltevrede
authors.affiliation: National Institute of Public Health and the Environment (RIVM), Centre for Infectious Disease Control, Centre Infectious Diseases, Epidemiology and Surveillance, Antonie van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands; University of Groningen, University Medical Center Groningen, Department of Epidemiology, P.O. Box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: renske.eilers@rivm.nl.
authors.forename: Renske
authors.initials: R
authors.lastname: Eilers
authors.affiliation: National Institute of Public Health and the Environment (RIVM), Centre for Infectious Disease Control, Centre Infectious Diseases, Epidemiology and Surveillance, Antonie van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands. Electronic address: hester.de.melker@rivm.nl.
authors.forename: Hester E
authors.initials: HE
authors.lastname: de Melker
authors.affiliation: National Institute of Public Health and the Environment (RIVM), Centre for Infectious Disease Control, Centre for Immunology of Infectious Diseases and Vaccines, Antonie van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands. Electronic address: debbie.van.baarle@rivm.nl.
authors.forename: Debbie
authors.initials: D
authors.lastname: van Baarle
mesh_terms: D000368:Aged; D003587:Cytomegalovirus / Q000276:immunology*; D003586:Cytomegalovirus Infections / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory; D000068884:Immunosenescence; D008875:Middle Aged; D013601:T-Lymphocytes / Q000502:physiology*
keywords: Cytomegalovirus; Immunosenescence; Memory T cells; T cell subsets; TEMRA