A Novel CXCR4 Targeting Protein SDF-1/54 as an HIV-1 Entry Inhibitor
Suiyi Tan1, Wenjuan Li1, Zhaofeng Li1
1Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China.
Abstract:
CXC chemokine receptor 4 (CXCR4) is a co-receptor for HIV-1 entry into target cells. Its natural ligand, the chemokine SDF-1, inhibits viral entry mediated by this receptor. However, the broad expression pattern of CXCR4 and its critical roles in various physiological and pathological processes indicate that the direct application of SDF-1 as an entry inhibitor might have severe consequences. Previously, we constructed an effective SDF-1 mutant, SDF-1/54, by deleting the α-helix of the C-terminal functional region of SDF-1. Of note, SDF-1/54 shows remarkable decreased chemotoxic ability, but maintains a similar binding affinity to CXCR4, suggesting SDF-1/54 might better serve as a CXCR4 inhibitor. Here, we found that SDF-1/54 exhibited potent antiviral activity against various X4 HIV-1 strains, including the infectious clone HIV-1 NL4-3, laboratory-adapted strain HIV-1 IIIB, clinical isolates and even drug-resistant strains. By using time-of-addition assay, non-infectious and infectious cell-cell fusion assay and CXCR4 internalization assay, we demonstrated SDF-1/54 is an HIV-1 entry inhibitor. A combination of SDF-1/54 with several antiretroviral drugs exhibited potent synergistic anti-HIV-1 activity. Moreover, SDF-1/54 was stable and its anti-HIV-1 activity was not significantly affected by the presence of seminal fluid, vaginal fluid simulant and human serum albumin. SDF-1/54 showed limited in vitro cytotoxicity to lymphocytes and vaginal epithelial cells. Based on these findings, SDF-1/54 could have a therapeutic potential as an HIV-1 entry inhibitor.
Insights
A modified chemokine, SDF-1/54, effectively inhibits HIV-1 entry by targeting the CXCR4 co-receptor. This mutant shows potent antiviral activity with reduced toxicity, offering therapeutic potential for HIV-1 infection.
Area of Science:
- Virology
- Immunology
- Drug Discovery
Background:
- CXC chemokine receptor 4 (CXCR4) is essential for HIV-1 entry.
- Natural ligand SDF-1 inhibits viral entry but has toxicity concerns.
- SDF-1/54, an SDF-1 mutant, retains CXCR4 binding with reduced chemotoxicity.
Purpose of the Study:
- To evaluate the antiviral activity and therapeutic potential of SDF-1/54 as an HIV-1 entry inhibitor.
- To assess the mechanism of action and stability of SDF-1/54.
- To determine the safety profile of SDF-1/54 in relevant biological fluids and cell types.
Main Methods:
- Construction and characterization of SDF-1 mutant SDF-1/54.
- Antiviral assays against various X4 HIV-1 strains (NL4-3, IIIB, clinical isolates, drug-resistant strains).
- Time-of-addition, cell-cell fusion, and CXCR4 internalization assays to confirm entry inhibition.
- Synergy testing with antiretroviral drugs.
- Stability assays in seminal fluid, vaginal fluid simulant, and human serum albumin.
- In vitro cytotoxicity assays on lymphocytes and vaginal epithelial cells.
Main Results:
- SDF-1/54 demonstrated potent antiviral activity against diverse X4 HIV-1 strains.
- Mechanism studies confirmed SDF-1/54 acts as an HIV-1 entry inhibitor.
- SDF-1/54 exhibited synergistic effects when combined with existing antiretroviral drugs.
- The mutant showed stability in biological fluids and limited in vitro cytotoxicity.
- SDF-1/54 maintained high binding affinity to CXCR4 with significantly reduced chemotoxicity.
Conclusions:
- SDF-1/54 is a potent HIV-1 entry inhibitor with a favorable safety profile.
- Its stability and efficacy against various HIV-1 strains suggest therapeutic potential.
- SDF-1/54 may offer a novel strategy for HIV-1 treatment, potentially in combination therapy.
