Rational Engineering of a Sub-Picomolar HIV-1 Blocker.

Area of Science:

• Virology
• Immunology
• Protein Engineering

Background:

• HIV-1 entry relies on CCR5 and gp41 interactions.
• Developing potent and broad-spectrum HIV-1 inhibitors is crucial.

Purpose of the Study:

• To design and characterize a novel fusion protein combining CCR5 and gp41 inhibitory functions.
• To evaluate the antiviral activity and synergistic potential of the CCL5 5p12 5m-C37 fusion protein.

Main Methods:

• cDNA fusion of CCL5 5p12 5m (CCR5 antagonist) and C37 (gp41 inhibitor).
• Expression of the fusion protein in *E. coli*.
• Antiviral assays against various HIV-1 strains (R5, R5/X4, X4).
• Combination studies with tenofovir (TDF) and maraviroc (MVC).

Main Results:

• CCL5 5p12 5m-C37 demonstrated potent inhibition of R5 HIV-1 strains (low to sub-picomolar IC50).
• The fusion protein effectively inhibited R5/X4 and X4 HIV-1 strains in the picomolar range.
• Synergistic antiviral effects were observed when combined with TDF and MVC.
• The combination with MVC suggested extensive engagement of CCR5 conformational populations.

Conclusions:

• The CCL5 5p12 5m-C37 fusion protein is a potent HIV-1 entry inhibitor targeting multiple mechanisms.
• This engineered protein represents a promising lead for developing new HIV-1 therapies and pre-exposure prophylaxis.