title: Mouse T-cells restrict replication of human immunodeficiency virus at the level of integration.
abstract: BACKGROUND
  The development of an immunocompetent, genetically modified mouse model to study HIV-1 pathogenesis and to test antiviral strategies has been hampered by the fact that cells from native mice do not or only inefficiently support several steps of the HIV-1 replication cycle. Upon HIV-1 infection, mouse T-cell lines fail to express viral proteins, but the underlying replication barrier has thus far not been unambiguously identified. Here, we performed a kinetic and quantitative assessment of consecutive steps in the early phase of the HIV-1 replication cycle in T-cells from mice and humans.
  
  
  RESULTS
  Both T-cell lines and primary T-cells from mice harbor a severe post-entry defect that is independent of potential species-specTR transactivation. Reverse transcription occurred efficiently following VSV-G-mediated entry of virions into mouse T-cells, and abundant levels of 2-LTR circles indicated successful nuclear import of the pre-integration complex. To probe the next step in the retroviral replication cycle, i.e. the integration of HIV-1 into the host cell genome, we established and validated a nested real-time PCR to specifically quantify HIV-1 integrants exploiting highly repetitive mouse B1 elements. Importantly, we demonstrate that the frequency of integrant formation is diminished 18- to > 305-fold in mouse T-cell lines compared to a human counterpart, resulting in a largely abortive infection. Moreover, differences in transgene expression from residual vector integrants, the transcription off which is cyclin T1-independent, provided evidence for an additional, peri-integrational deficit in certain mouse T-cell lines.
  
  
  CONCLUSIONS
  In contrast to earlier reports, we find that mouse T-cells efficiently support early replication steps up to and including nuclear import, but restrict HIV-1 at the level of chromosomal integration.
authors.affiliation: Department of Virology, University of Heidelberg, Heidelberg, Germany. Hanna-Mari.Tervo@med.uni-heidelberg.de
authors.forename: Hanna-Mari
authors.initials: HM
authors.lastname: Tervo
authors.forename: Christine
authors.initials: C
authors.lastname: Goffinet
authors.forename: Oliver T
authors.initials: OT
authors.lastname: Keppler
mesh_terms: D000818:Animals; D002460:Cell Line; D004279:DNA, Viral / Q000096:biosynthesis; D005260:Female; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D048348:Reverse Transcription; D013601:T-Lymphocytes / Q000821:virology*; D014158:Transcription, Genetic; D016662:Virus Integration; D053586:Virus Internalization
chemical_list: D004279:DNA, Viral