Inhibition of HIV-1 infection by down-regulation of the CXCR4 co-receptor using an intracellular single chain variable fragment against CXCR4.
CXCR4 is the major co-receptor used by X4 strains of human immunodeficiency virus type I (HIV-1). In HIV-1-infected patients, the appearance of X4 strains (T cell line-tropic) correlates with disease progression. Since its discovery, the CXCR4 co-receptor has been a major target for different agents which block its function, such as stromal-derived factor 1alpha (SDF-1alpha) and the anti-CXCR4 monoclonal antibody, 12G5. In the present studies, the 12G5 hybridoma was used to construct a single-chain variable antibody fragment (SFv). Murine leukemia virus (MLV) and simian virus 40 (SV(40)) were utilized as delivery vehicles for the anti-CXCR4 SFv. Intracellular expression of the anti-CXCR4 SFv led to down-regulation of this critical co-receptor, as demonstrated by immunostaining. This effect significantly and specifically protected transduced cells from challenge with HIV-1, as measured by HIV-1 p24 antigen expression. Inhibition of HIV-1 replication was specific for X4 HIV-1 strains as demonstrated by MAGI assays. HeLa-CD4/betagal-CCR5 cells expressing the anti-CXCR4 SFv showed significant inhibition of infectivity by the X4 HIV-1 strain NL4-3, but not with the R5 HIV-1 strain Bal. Thus, this anti-HIV-1 molecular therapy has the potential to inhibit HIV-1 replication and virion spread. Targeting CXCR4 by intracellular immunization could be of additional benefit to certain HIV-1-infected patients on highly active antiretroviral therapy (HAART).
BouHamdan
M
M
The Dorrance H Hamilton Laboratories, Center for Human Virology, Division of Infectious Diseases, Department of Medicine, USA.
Strayer
D S
DS
Wei
D
D
Mukhtar
M
M
Duan
L X
LX
Hoxie
J
J
Pomerantz
R J
RJ
D000818:Animals; D002460:Cell Line; D015536:Down-Regulation; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D015658:HIV Infections / Q000378:metabolism / Q000628:therapy*; D015497:HIV-1 / Q000502:physiology; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics; D009052:Leukemia Virus, Murine / Q000235:genetics; D019718:Receptors, CXCR4 / Q000235:genetics / Q000378:metabolism*; D013539:Simian virus 40 / Q000235:genetics; D013601:T-Lymphocytes / Q000821:virology; D014779:Virus Replication
D007135:Immunoglobulin Variable Region; D019718:Receptors, CXCR4