Lentiviral Vector Integration Profiles Differ in Rodent Postmitotic Tissues

Abstract

Lentiviral vectors with self-inactivating (SIN) long terminal repeats (LTRs) are promising for safe and sustained transgene expression in dividing as well as quiescent cells. As genome organization and transcription substantially differs between actively dividing and postmitotic cells in vivo, we hypothesized that genomic vector integration preferences might be distinct between these biological states. We performed integration site (IS) analyses on mouse dividing cells (fibroblasts and hematopoietic progenitor cells (HPCs)) transduced ex vivo and postmitotic cells (eye and brain) transduced in vivo. As expected, integration in dividing cells occurred preferably into gene coding regions. In contrast, postmitotic cells showed a close to random frequency of integration into genes and gene spare long interspersed nuclear elements (LINE). Our studies on the potential mechanisms responsible for the detected differences of lentiviral integration suggest that the lowered expression level of Psip1 reduce the integration frequency in vivo into gene coding regions in postmitotic cells. The motif TGGAA might represent one of the factors for preferred lentiviral integration into mouse and rat Satellite DNA. These observations are highly relevant for the correct assessment of preclinical biosafety studies, indicating that lentiviral vectors are well suited for safe and effective clinical gene transfer into postmitotic tissues.

Ocular gene delivery using lentiviral vectors

“…75 HIV-1 or EIAV vectors in vitro, for example, consistently favour integration into active coding regions in dividing human cell lines, unlike retroviral MoLV vectors, which favour integration near transcriptional start sites. [76][77][78] HIV-1 integration in (post-mitotic) murine or rat RPE in vivo does not appear to show site preference for these regions, and instead shows near-random and uniform frequency of integration into genes and gene spare long interspersed nuclear elements, 79 suggesting that the risk of integrating HIV-1-related IM in post-mitotic tissues is probably low, and lower than in mitotically active cells. The in vivo intraocular vector integration profiles of lentiviruses other than HIV-1 have not been reported, but are also likely to be influenced by the degree of target cell mitosis.…”

Absence of ocular malignant transformation after sub-retinal delivery of rAAV2/2 or integrating lentiviral vectors in p53-deficient mice

“…12,13 Recent work points towards there being less integration preference for active regions in postmitotic rodent cells in vivo, with integration instead being near random, and of uniform frequency into genes and gene spare long interspersed nuclear elements. 14 Thus far, IM leading to malignancies in patients has only been described in dividing cells of the haematopoietic system. It remains to be determined, however, whether naturally quiescent cells, including photoreceptor (PR) cells or the essentially quiescent retinal pigment epithelium (RPE) in the retina are similarly at risk, as non-dividing cells are thought to require more than a single mutagenic event.…”

A lentiviral vector-based therapeutic vaccine encoding Ag85B-Rv3425 potently increases resistance to acute tuberculosis infection in mice

“…Lentiviral vectors, which have been successfully used in the first clinical trial of patients with advanced leukemia [7,8], are good candidates for gene therapy promising for sustained and safe trans-gene expression in dividing as well as non-dividing cells [9]. Moreover, in vivo administration of foreign protein by lentiviral vectors could induce antigen-specific immune responses.…”