A genetic immunization adjuvant system based on BVP22-antigen fusion

Area of Science:

• Immunology
• Vaccinology
• Molecular Biology

Background:

• DNA vaccines require enhanced immune responses for clinical efficacy.
• The bovine herpesvirus 1 (BHV-1) protein VP22 possesses unique trafficking traits.
• Investigating novel strategies to improve genetic immunization is crucial.

Purpose of the Study:

• To evaluate the efficacy of fusing BHV-1 protein VP22 to an antigen for genetic immunization.
• To determine if BVP22 enhances immune responses compared to standard DNA immunization.
• To assess the impact of BVP22 fusion on antibody production, T helper cell responses, and cytotoxic T lymphocyte activity.

Main Methods:

• Mice were intramuscularly injected with gene constructs encoding yellow fluorescent protein (YFP) alone, YFP fused to BVP22, or YFP fused to BHV-1 tegument protein VP16 (BVP16).
• Antibody responses, including IgG2a/IgG1 ratios, were measured.
• T helper 1 (Th1) cytokine levels (IFN-gamma, IL-4) and cytotoxic T lymphocyte (CTL) responses were assessed.

Main Results:

• DNA immunization with BVP22-YFP elicited significantly higher YFP-specific antibody responses compared to YFP or BVP16-YFP immunization.
• The BVP22-YFP construct promoted a stronger Th1-biased immune response, indicated by cytokine profiles and IgG2a/IgG1 ratios.
• A greater cytotoxic T lymphocyte response was observed following BVP22-YFP genetic immunization.

Conclusions:

• Fusion of BHV-1 protein VP22 to antigens acts as a genetic adjuvant, significantly enhancing DNA vaccine-induced immune responses.
• BVP22-mediated genetic immunization offers a promising strategy to improve the clinical effectiveness of DNA vaccines.
• The trafficking properties of BVP22 are key to its adjuvant effect in DNA vaccination.