Expression of Human Immunodeficiency Virus Type 1 Neutralizing Antibody Fragments Using Human Vaginal Lactobacillus

Area of Science:

• Microbiology
• Immunology
• Biotechnology

Background:

• Developing an effective human immunodeficiency virus type 1 (HIV-1) vaccine remains a global health priority.
• Generating broadly neutralizing antibodies (bNAbs) against HIV-1 epitopes is challenging.
• Passive immunization strategies, such as topical microbicides, are crucial for HIV prevention.

Purpose of the Study:

• To assess the feasibility of expressing single-chain variable fragments (scFvs) and single-domain antibodies (dAbs) in Lactobacillus species.
• To develop Lactobacillus as a live biotherapeutic for delivering anti-HIV antibodies to mucosal surfaces.
• To evaluate the expression, functionality, and neutralization capacity of engineered Lactobacillus strains.

Main Methods:

• Cloning and expression of anti-HIV antibody fragments (m9, m36, m36.4) in Lactobacillus jensenii.
• Quantification of antibody fragment expression levels.
• Assessment of antibody binding to gp120/CD4 complex.
• HIV-1 neutralization assays (TZM-bl assay) to determine efficacy and breadth.

Main Results:

• Engineered Lactobacillus jensenii successfully expressed antibody fragments m9, m36, and m36.4.
• Smaller dAbs (m36/m36.4) were expressed at higher levels (≥3 μg/ml).
• Lactobacillus-produced m36.4 demonstrated binding to gp120/CD4 and inhibited HIV-1_BaL infection in vitro.

Conclusions:

• Lactobacillus is a viable platform for expressing functional anti-HIV antibody fragments.
• Lactobacillus-delivered dAbs can provide passive mucosal immunity.
• This approach offers a promising strategy for topical HIV-1 prevention via live biotherapeutics.