Mutation-Tolerant Inhibition of HIV-1 Integrase Strand Transfer by Secondary Metabolites from the Endophytic Fungus...

Area of Science:

• Mycology
• Virology
• Medicinal Chemistry

Background:

• Endophytic fungi are a rich source of novel antiviral compounds.
• The crude extract from Alternaria alternata PO4PR2 (PO4PR2) has demonstrated prior anti-HIV-1 activity.

Purpose of the Study:

• To evaluate the efficacy of the PO4PR2 extract against integrase strand-transfer inhibitor (INSTI)-resistant HIV-1.
• To elucidate the mechanism of action of the extract against drug-resistant HIV-1.

Main Methods:

• Site-directed mutagenesis was used to introduce key INSTI resistance mutations into HIV-1.
• Viral infectivity, cytotoxicity, and antiviral activity were assessed using cell-based assays.
• Integrase activity assays and Alu-gag nested PCR were employed to evaluate viral DNA integration inhibition.

Main Results:

• The PO4PR2 extract potently inhibited INSTI-resistant HIV-1 mutants with low IC50 values (0.02971–0.1652 μg/mL) and minimal cytotoxicity (CC50 = 300 μg/mL).
• The extract inhibited 67% of integrase activity, specifically targeting the strand-transfer step, and reduced integrated viral DNA.
• Molecular docking identified coumarin derivatives as potential bioactive metabolites with mutation-tolerant binding to the integrase catalytic pocket.

Conclusions:

• The PO4PR2 extract is a promising source for developing novel therapeutics against drug-resistant HIV-1.
• Coumarin derivatives from PO4PR2 may represent a new class of compounds targeting resistant HIV-1 integrase.