Consensus Integrase of a New HIV-1 Genetic Variant CRF63_02A1.

Area of Science:

• Virology
• Molecular Biology
• Biochemistry

Background:

• Human immunodeficiency virus type 1 (HIV-1) exhibits high genetic variability, leading to the emergence of diverse viral strains.
• The recombinant virus CRF63_02A1 is prevalent in the Siberian Federal District of Russia.
• HIV-1 integrase (IN) is a crucial enzyme for viral DNA integration into the host cell genome.

Purpose of the Study:

• To characterize the DNA-binding and catalytic activities of the HIV-1 CRF63_02A1 integrase (IN_CRF).
• To investigate the impact of specific mutations on IN_CRF activity and raltegravir sensitivity.

Main Methods:

• Design of a consensus sequence for IN_CRF.
• Recombinant IN_CRF production and purification.
• Characterization of DNA-binding kinetics, complex stability, and catalytic activities (3'-processing and strand transfer).
• Assessment of drug resistance mutations' effects on IN_CRF activity and raltegravir inhibition.

Main Results:

• IN_CRF demonstrated significantly higher rates of complex formation with DNA substrates compared to subtype A and B integrases.
• The catalytic rates and efficiencies of 3'-processing and strand transfer reactions mediated by IN_CRF were elevated.
• Specific amino acid substitutions in the N-terminal domain of IN_CRF are likely responsible for its enhanced activity.
• Drug resistance mutations (Q148K/G140S and G118R/E138K) substantially reduced IN_CRF catalytic activity and raltegravir sensitivity, with a more pronounced effect for the double mutation.

Conclusions:

• HIV-1 CRF63_02A1 integrase possesses distinct biochemical properties, including enhanced DNA binding and catalytic efficiency, potentially linked to N-terminal domain variations.
• The characterized drug resistance mutations significantly impair IN_CRF function and reduce susceptibility to the integrase inhibitor raltegravir, highlighting potential challenges in treatment strategies.