eCD4-Ig Variants That More Potently Neutralize HIV-1

Area of Science:

• Virology
• Immunology
• Drug Discovery

Background:

• Human immunodeficiency virus type 1 (HIV-1) entry inhibitor eCD4-Ig combines CD4-Ig and a coreceptor-mimetic peptide.
• eCD4-Ig demonstrates superior potency to CD4-Ig, approaching that of broadly neutralizing antibodies (bNAbs).
• Unlike bNAbs, eCD4-Ig neutralizes all tested HIV-1, HIV-2, and SIV isolates, indicating potential clinical utility against antibody escape.

Purpose of the Study:

• To characterize three novel eCD4-Ig variants with distinct architectures utilizing stabilized CD4 domain 1 (D1.22).
• To evaluate the potency, thermal stability, and effector functions of these new variants compared to the original eCD4-Ig.
• To identify key mutations contributing to enhanced potency for optimizing future HIV-1 inhibitor development.

Main Methods:

• Construction and characterization of three new eCD4-Ig variants (eD1.22-HL-Ig, eD1.22-Ig, eD1.22-D2-Ig).
• Assessment of neutralization efficiency against various HIV and SIV isolates.
• Evaluation of antibody-dependent cell-mediated cytotoxicity (ADCC) and gp120 shedding.
• Analysis of thermal stability and prevention of CCR5-positive, CD4-negative cell infection.

Main Results:

• The new variants were 10- to 20-fold more potent than the original eCD4-Ig, with eD1.22-HL-Ig showing the highest potency.
• eD1.22-HL-Ig exhibited reduced ADCC activity, while eD1.22-D2-Ig demonstrated improved thermal stability and blocked CCR5-positive, CD4-negative cell infection.
• All variants efficiently mediated gp120 shedding, surpassing CD4-Ig.
• Introducing three D1.22 mutations into eCD4-Ig yielded a variant 9-fold more potent than eCD4-Ig.

Conclusions:

• Novel eCD4-Ig variants exhibit significantly enhanced potency and broad neutralization capabilities against HIV and related viruses.
• Specific variants offer optimized properties for different applications, including improved neutralization, thermal stability, and effector functions.
• These findings provide a basis for developing next-generation eCD4-Ig inhibitors for HIV prophylaxis, therapy, and cure strategies.