Inhibition of human immunodeficiency virus transmission to CD4+ T cells after gene transfer of constitutively expressed interferon beta to dendritic cells

Low autocrine interferon beta production as a gene therapy approach for AIDS: Infusion of interferon beta-engineered lymphocytes in macaques chronically infected with SIVmac251

Background

The aim of this study was to evaluate gene therapy for AIDS based on the transduction of circulating lymphocytes with a retroviral vector giving low levels of constitutive macaque interferon β production in macaques chronically infected with a pathogenic isolate of SIVmac251.

Results

Two groups of three animals infected for more than one year with a pathogenic primary isolate of SIVmac251 were included in this study. The macaques received three infusions of their own lymphocytes transduced ex vivo with the construct encoding macaque IFN-β (MaIFN-β or with a vector carrying a version of the MaIFN-β gene with a deletion preventing translation of the mRNA. Cellular or plasma viremia increased transiently following injection in most cases, regardless of the retroviral construct used. Transduced cells were detected only transiently after each infusion, among the peripheral blood mononuclear cells of all the animals, with copy numbers of 10 to 1000 per 10⁶ peripheral mononuclear cells.

Conclusion

Long-term follow-up indicated that the transitory presence of such a small number of cells producing such small amounts of MaIFN-β did not prevent animals from the progressive decrease in CD4⁺ cell count typical of infection with simian immunodeficiency virus. These results reveal potential pitfalls for future developments of gene therapy strategies of HIV infection.

A non-classical ISRE/ISGF3 pathway mediates induction of RANTES gene transcription by type I IFNs

RANTES (regulated upon activation normal T cell expressed and secreted) is a chemoattractant cytokine important in the generation of inflammatory responses and human immunodeficiency virus resistance. In hematopoietic cells, RANTES is over-expressed by type I interferons (IFN-alpha and IFN-beta). The upstream region of the RANTES gene promoter contains a distal low affinity IFN-stimulated response element (ISRE). Specific mutagenesis in this ISRE-like motif abolished the activation of RANTES transcription by type I IFNs. Examination of the ISRE binding factors strongly suggested that signal transducer and activator of transcription (Stat)-2 and p48/IFN-stimulated gene factor 3gamma (ISGF3gamma) are not required for the induction of RANTES by type I IFNs. The specific requirement of Stat-1 was demonstrated using Stat-1-deficient U3A cells. These results revealed a non-classical ISRE/ISGF3 signal transduction pathway for the induction of RANTES by type I IFNs.