DNA vaccines encoding DEC205-targeted antigens: immunity or tolerance?

Area of Science:

• Immunology
• Vaccinology
• Molecular Biology

Background:

• Targeting antigens to the DEC205 receptor enhances dendritic cell (DC) antigen presentation.
• DEC205-targeted protein vaccines with adjuvants induce immunity, while without adjuvants, they can induce tolerance.
• The immunogenicity of DNA vaccines encoding DEC205-targeted antigens is less understood.

Purpose of the Study:

• To investigate the immunogenicity and efficacy of a DC-targeted DNA vaccine against influenza A virus (IAV).
• To explore whether DEC205 targeting influences T-cell responses and protection against IAV infection.
• To evaluate the potential of these vaccines in inducing tolerance or immunity.

Main Methods:

• Constructed DNA vaccines encoding influenza hemagglutinin (HA) targeted to DEC205 via a single-chain antibody.
• Delivered vaccines via electroporation in wild-type BALB/c mice and T-cell receptor-transgenic mice.
• Assessed T-cell responses, protection against IAV challenge, and regulatory T-cell expansion using adoptive transfer experiments.

Main Results:

• DEC205-targeted HA enhanced antigen presentation on MHC class II and CD4 T-cell activation in transgenic models.
• However, targeted DNA vaccination in wild-type mice led to reduced T-cell responses and less protection against IAV compared to non-targeted vaccines.
• Adoptive transfer ruled out T-cell deletion, but revealed local expansion of antigen-specific regulatory T cells, suppressing effector cell activation.

Conclusions:

• DNA vaccines encoding DEC205-targeted antigens induced peripheral tolerance, not immunity, in this study.
• The findings suggest a mechanism involving regulatory T cells that suppresses protective immunity.
• Further research is needed to understand and potentially overcome this tolerance induction for effective vaccine development.