DNA-based immunization induces anti-CD4 antibodies directed primarily to native epitopes

Area of Science:

• Immunology
• Molecular Biology
• Vaccinology

Background:

• DNA-based immunization is a promising strategy for inducing protective immunity.
• It offers potential advantages over recombinant antigens, possibly by targeting conformational epitopes.
• The CD4 molecule serves as a model to compare antibody responses.

Purpose of the Study:

• To compare the antibody responses induced by DNA-based immunization versus recombinant protein immunization.
• To evaluate the quality and consistency of antibodies generated against native CD4 molecules.
• To analyze the kinetics and isotype distribution of antibody responses.

Main Methods:

• Mice were immunized with either plasmid DNA encoding CD4 (CD4-DNA) or recombinant soluble CD4 (rCD4).
• Antibody titers recognizing rCD4 were measured.
• Reactivity of antibodies with native cell surface CD4 was assessed.
• Antibody isotype distribution was analyzed.

Main Results:

• CD4-DNA immunization induced antibodies reactive with native cell surface CD4 in all mice, unlike rCD4 immunization.
• Antibodies against native CD4 appeared earlier after CD4-DNA immunization.
• CD4-DNA induced a broader isotype distribution, while rCD4 favored IgG1 (TH2 response).

Conclusions:

• DNA immunization generates a more consistent and qualitatively superior antibody response against native CD4.
• Endogenously produced CD4 via DNA immunization is expressed in a native conformation, enhancing immunogenicity.
• DNA immunization offers advantages over recombinant protein immunization for eliciting antibodies against conformational epitopes.