Successful immunization with a single injection of non-integrating lentiviral vector

We evaluated the ability of an integrase ( IN)-defective self-inactivating lentiviral vector ( sinLV) for the delivery of human immunodeficiency virus-1( HIV-1) envelope sequences in mice to elicit specific immune responses. BALB/c mice were immunized with a single intramuscular injection of the IN-defective sinLV expressing the codon optimized HIV-1(JR-FL) gp120 sequence, and results were compared with those for the IN-competent counterpart. The IN-defective sinLV elicited specific and longlasting immune responses, as evaluated up to 90 days from the immunization by enzyme-linked immunosorbent spot ( ELISPOT) and intracellular staining ( ICS) for interferon-gamma( IFN-gamma) assays in both splenocytes and bone marrow ( BM) cells, chromium release assay in splenocytes, and antibody detection in sera, without integration of the vector into the host genome. These data provide evidence that a single administration of an IN-defective sinLV elicits a significant immune response in the absence of vector integration and may be a safe and useful strategy for vaccine development.