The Virus Entry Pathway Determines Sensitivity to the Antiviral Peptide TAT-I24

Area of Science:

• Virology
• Molecular Biology
• Drug Discovery

Background:

• The peptide TAT-I24 demonstrated in vitro neutralization of double-stranded DNA viruses.
• Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) variants pose a significant global health challenge.

Purpose of the Study:

• To evaluate the antiviral efficacy of TAT-I24 against SARS-CoV-2, including different variants.
• To investigate the mechanism underlying TAT-I24's antiviral activity and its dependence on virus entry pathways.

Main Methods:

• Testing TAT-I24 neutralization of SARS-CoV-2 (Wuhan, Delta, Omicron) in Vero E6 and Calu-3 cell lines.
• Assessing the impact of chloroquine, an endocytosis inhibitor, on viral sensitivity to TAT-I24.
• Microscopic analysis of fluorescently labeled TAT-I24 localization and co-localization with endosomal markers (Rab5, Rab14) in COS-7 cells.

Main Results:

• TAT-I24 dose-dependently neutralized the Wuhan SARS-CoV-2 isolate in Vero E6 cells.
• TAT-I24 failed to neutralize Delta and Omicron SARS-CoV-2 variants in Vero E6 cells and all variants in Calu-3 cells.
• The Wuhan variant's sensitivity to TAT-I24 was enhanced by chloroquine, suggesting an endocytosis-dependent mechanism.
• Microscopy revealed TAT-I24 localizes to endosomes and co-localizes with Rab14, not Rab5, indicating involvement in specific endosomal pathways.

Conclusions:

• The antiviral efficacy of TAT-I24 against SARS-CoV-2 is variant-dependent and influenced by the virus's cellular entry mechanism.
• Endocytosis appears to be a critical pathway for TAT-I24's antiviral action against SARS-CoV-2.