Inhibition of Infectious HIV-1 Production by Rerouting the Cellular Furin Inhibitor Serpin B8

Area of Science:

• Biochemistry
• Virology
• Molecular Biology

Background:

• Serpins regulate physiological processes by inhibiting serine proteases.
• Human immunodeficiency virus type 1 (HIV-1) utilizes the serine protease furin for its envelope glycoprotein (Env) maturation.
• Serpin Family B Member 8 (Serpin B8) is an endogenous inhibitor of furin.

Purpose of the Study:

• To investigate if Serpin B8 can interfere with HIV-1 Env maturation and reduce viral infectivity.
• To determine if subcellular relocalization of Serpin B8 can enhance its anti-HIV-1 activity.

Main Methods:

• In vitro assays using recombinant Serpin B8 and an HIV-1 Env reporter substrate.
• Expression of Serpin B8 in HIV-1-producing cells.
• Immunofluorescence imaging, dimerization assays, and in silico sequence analyses.
• Engineering Serpin B8 with a heterologous signal peptide for altered subcellular localization.

Main Results:

• Recombinant Serpin B8 inhibited furin-mediated cleavage of an HIV-1 Env reporter substrate in vitro.
• Serpin B8 did not affect Env maturation or HIV-1 infectivity when expressed in producing cells due to distinct subcellular localizations.
• Relocalization of Serpin B8 to secretory compartments via a signal peptide conferred potent anti-HIV-1 activity, significantly decreasing viral infectivity.

Conclusions:

• Subcellular relocalization of Serpin B8 enables efficient inhibition of infectious HIV-1 production.
• Protein engineering of endogenous protease inhibitors can be a viable strategy for developing novel antiviral therapies against HIV-1.