Mutations in the 3'-PPT Lead to HIV-1 Replication without Integration.

Area of Science:

• Virology
• Molecular Biology
• Antiviral Drug Resistance

Background:

• Retroviral genome integration is essential for the viral life cycle.
• Strand-transfer inhibitors (INSTIs) target integration but can drive resistance mutations in the integrase gene.
• Some INSTI treatment failures lack integrase gene mutations, suggesting alternative resistance pathways.

Purpose of the Study:

• To investigate a novel mechanism of INSTI resistance in HIV-1.
• To characterize the replication of INSTI-resistant viruses with mutations outside the integrase gene.
• To elucidate the role of unintegrated viral DNA in HIV-1 replication under drug pressure.

Main Methods:

• Selection of a dolutegravir-resistant HIV-1 strain with mutations in the 3 acronym{'-PPT'}.
• Analysis of viral DNA forms, including integrated and unintegrated forms (e.g., 1-LTR circles).
• Assessment of viral replication efficiency in the presence of INSTIs.

Main Results:

• A selected dolutegravir-resistant virus with 3 acronym{'-PPT'} mutations replicated effectively despite lacking integrated viral DNA.
• The 3 acronym{'-PPT'} mutation led to the accumulation of 1-LTR circles, not linear DNA intermediates.
• Viral replication occurred via these 1-LTR circles, bypassing the need for integration.

Conclusions:

• A novel INSTI resistance mechanism involves 3 acronym{'-PPT'} mutations, leading to replication through 1-LTR circles.
• This pathway confers resistance without altering the integrase gene.
• Unintegrated viral DNA, specifically 1-LTR circles, plays a significant role in HIV-1 replication and drug resistance.