A genetically engineered spleen necrosis virus-derived retroviral vector that displays the HIV type 1 glycoprotein 120 envelope peptide.
We reported that SNV-derived retroviral vectors, which display single-chain antibodies on the viral surface, enable cell type-specific gene delivery into various human cells. In particular, the SNV cell type-specific gene delivery vector system appears to be well suited to transduce genes into cells of the human hematopoietic system (Jiang et al., J. Virol. 72:10148-10156, 1998). Here, we report the construction of SNV vector particles that display the complete gp120 surface unit of the envelope protein of human immunodeficiency virus type 1 (HIV-1) on the viral surface. The complete gp120-coding region of a T cell-tropic HIV-1 strain (LAI/BRU) was fused to a short peptide spacer coding region [(Gly4Ser)3] linking it to the SNV TM-coding region. The corresponding protein was expressed as a single 145-kDa peptide as expected. This peptide was nontoxic and could be stably expressed in dog D17 SNV-derived packaging cells. Particles harvested from stable packaging lines infected CD4+ human hematopoietic cells with titers exceeding 10(5) CFU/ml supernatant tissue culture medium. Titers in other, CD4- cell lines expressing various coreceptors of HIV-1 were 100-fold lower than titers obtained in CD4+ cells. Specificity of infection was demonstrated by antibody inhibition assays or by preincubating cells with SDF-1alpha, the ligand, which binds to the CXCR4 coreceptor, to which this gp120 binds. Our data indicate that binding of the HIV-1 gp120 to either CD4 or CXCR4 is sufficient to enable infection of human cells with SNV vector particles. We constructed retroviral vector particles that display chimeric HIV-1-SU-SNV-TM proteins plus wild-type SNV envelope on the viral surface. Such particles allowed efficient infection of CD4-positive human T lymphocytes, and, at a lower efficiency, also cells expressing CXCR4 without CD4. These data coincide with our earlier hypothesis that the chimeric envelope is required only to bind the vector particle to a cell surface receptor of the target cell, while membrane fusion is mediated by wild-type Env, which alone is not sufficient to enable infection of human cells.
Jiang
A
A
Center for Human Virology, The Dorrance H. Hamilton Laboratories, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Fisher
H
H
Pomerantz
R J
RJ
Dornburg
R
R
D000818:Animals; D015704:CD4 Antigens / Q000235:genetics / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000821:virology*; D004285:Dogs; D018014:Gene Transfer Techniques; D005822:Genetic Vectors / Q000235:genetics*; D015699:HIV Envelope Protein gp120 / Q000235:genetics* / Q000378:metabolism; D015497:HIV-1 / Q000737:chemistry*; D006367:HeLa Cells / Q000821:virology; D006801:Humans; D008561:Membrane Fusion / Q000235:genetics; D019718:Receptors, CXCR4 / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013155:Spleen Focus-Forming Viruses / Q000235:genetics*
D015704:CD4 Antigens; D015699:HIV Envelope Protein gp120; D019718:Receptors, CXCR4; D011993:Recombinant Fusion Proteins