title: NK cells improve control of friend virus infection in mice persistently infected with murine cytomegalovirus.
abstract: BACKGROUND
  Co-infection of HIV patients with cytomegalovirus (CMV) is associated with enhanced AIDS progression and CMV end-organ diseases. On the other hand, persistent CMV infection has recently been shown to decrease tumor relapse and protect against lethal bacterial infection. The influence of persistent CMV on the outcome of an acute retroviral superinfection is still unknown.
  
  
  RESULTS
  Here we show that a persistent murine CMV (mCMV) infection surprisingly confers higher resistance to a primary Friend retrovirus infection (FV) of mice. Decreased FV titers and augmented FV-specific CD8 T-cell responses were found in mCMV infected mice during primary FV superinfection. NK cells produced higher amounts of IFNgamma after FV infection of persistently mCMV infected mice suggesting that these cells were involved in the 'protective' effect. Depletion of NK1.1+ cells or neutralization of IFNgamma during FV superinfection abrogated the mCMV-mediated effect.
  
  
  CONCLUSIONS
  Our data demonstrate for the first time that a persistent CMV infection induces long-lasting NK cell responses that can enhance immunity to primary retroviral infections. To our knowledge, studies investigating primary HIV infection have not analyzed the role of the CMV seropositivity in these patients. Our observations suggest that NK cells in CMV seropositive individuals might contribute to the control of primary HIV infection.
authors.affiliation: Institute for Virology of the University Hospital in Essen, University of Duisburg-Essen, Essen, Germany. kraft.anke@mh-hannover.de
authors.forename: Sandra
authors.initials: S
authors.lastname: Francois
authors.forename: Jing
authors.initials: J
authors.lastname: Peng
authors.forename: Tatjana
authors.initials: T
authors.lastname: Schwarz
authors.forename: Janine
authors.initials: J
authors.lastname: Duppach
authors.forename: Kathrin
authors.initials: K
authors.lastname: Gibbert
authors.forename: Ulf
authors.initials: U
authors.lastname: Dittmer
authors.forename: Anke Rm
authors.initials: AR
authors.lastname: Kraft
mesh_terms: D000818:Animals; D060085:Coinfection / Q000276:immunology / Q000821:virology; D004195:Disease Models, Animal; D060467:Disease Resistance; D005622:Friend murine leukemia virus / Q000276:immunology*; D006566:Herpesviridae Infections / Q000276:immunology* / Q000821:virology; D007694:Killer Cells, Natural / Q000276:immunology*; D007942:Leukemia, Experimental / Q000276:immunology* / Q000821:virology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018146:Muromegalovirus / Q000276:immunology*; D012192:Retroviridae Infections / Q000276:immunology* / Q000821:virology; D014412:Tumor Virus Infections / Q000276:immunology* / Q000821:virology