title: High Prevalence of Infectious Adeno-associated Virus (AAV) in Human Peripheral Blood Mononuclear Cells Indicative of T Lymphocytes as Sites of AAV Persistence.
abstract: Seroepidemiology shows that infections with adeno-associated virus (AAV) are widespread, but diverse AAV serotypes isolated from humans or nonhuman primates have so far not been proven to be causes of human disease. In view of the increasing success of AAV-derived vectors in human gene therapy, definition of the in vivo sites of wild-type AAV persistence and the clinical consequences of its reactivation is becoming increasingly urgent. Here, we identify the presumed cell type for AAV persistence in the human host by highly sensitive AAV PCRs developed for the full spectrum of human AAV serotypes. In genomic-DNA samples from leukocytes of 243 healthy blood donors, 34% were found to be AAV positive, predominantly AAV type 2 (AAV2) (77%), AAV5 (19%), and additional serotypes. Roughly 11% of the blood donors had mixed AAV infections. AAV prevalence was dramatically increased in immunosuppressed patients, 76% of whom were AAV positive. Of these, at least 45% displayed mixed infections. Follow-up of single blood donors over 2 years allowed repeated detection of the initial and/or additional AAV serotypes, suggestive of fluctuating, persistent infection. Leukocyte separation revealed that AAV resided in CD3+T lymphocytes, perceived as the putative in vivo site of AAV persistence. Moreover, infectious AAVs of various serotypes could be rescued and propagated from numerous samples. The high prevalence and broad spectrum of human AAVs in leukocytes closely follow AAV seroepidemiology. Immunosuppression obviously enhances AAV replication in parallel with activation of human cytomegalovirus (HCMV) and human herpesvirus 6 (HHV-6), reminiscent of herpesvirus-induced AAV activation.
  
  
  
  Adeno-associated virus is viewed as apathogenic and replication defective, requiring coinfection with adenovirus or herpesvirus for productive infection. In vivo persistence of a defective virus requires latency in specialized cell types to escape the host immune response until viral spread becomes possible. Reactivation from latency can be induced by diverse stimuli, including infections, typically induced upon host immunosuppression. We show for the first time that infectious AAV is highly prevalent in human leukocytes, specifically T lymphocytes, and that AAV is strongly amplified upon immunosuppression, along with reactivation of latent human herpesviruses. In the absence of an animal model to study the AAV life cycle, our findings in the human host will advance the understanding of AAV latency, reactivation, and in vivo pathogenesis.
authors.affiliation: Institute of Virology, Campus Benjamin Franklin, Charité Medical School, Berlin, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Hüser
authors.affiliation: Institute of Virology, Campus Benjamin Franklin, Charité Medical School, Berlin, Germany.
authors.forename: Dina
authors.initials: D
authors.lastname: Khalid
authors.affiliation: Institute of Virology, Campus Benjamin Franklin, Charité Medical School, Berlin, Germany.
authors.forename: Timo
authors.initials: T
authors.lastname: Lutter
authors.affiliation: Institute of Virology, Campus Benjamin Franklin, Charité Medical School, Berlin, Germany.
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Hammer
authors.affiliation: Institute of Virology, Campus Benjamin Franklin, Charité Medical School, Berlin, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Weger
authors.affiliation: Institute of Virology, Campus Benjamin Franklin, Charité Medical School, Berlin, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Heßler
authors.affiliation: Institute of Transfusion Medicine, Charité Medical School, Berlin, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Kalus
authors.affiliation: Institute of Transfusion Medicine, Charité Medical School, Berlin, Germany.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Tauchmann
authors.affiliation: Labor Berlin-Charité Vivantes GmbH, Berlin, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Hensel-Wiegel
authors.affiliation: Institut Kardiale Diagnostik und Therapie (IKDT), Berlin, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Lassner
authors.affiliation: Institute of Virology, Campus Benjamin Franklin, Charité Medical School, Berlin, Germany regine.heilbronn@charite.de.
authors.forename: Regine
authors.initials: R
authors.lastname: Heilbronn
mesh_terms: D004279:DNA, Viral; D000229:Dependovirus / Q000145:classification / Q000502:physiology*; D006801:Humans; D016867:Immunocompromised Host; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000821:virology*; D010322:Parvoviridae Infections / Q000453:epidemiology* / Q000821:virology*; D016133:Polymerase Chain Reaction; D015995:Prevalence; D016036:Seroepidemiologic Studies; D013601:T-Lymphocytes / Q000276:immunology / Q000821:virology*; D014775:Virus Activation; D017735:Virus Latency
chemical_list: D004279:DNA, Viral
keywords: T lymphocytes; adeno-associated virus; blood mononuclear cells; human herpesviruses; latency; leukocytes; molecular epidemiology; persistence