Optimization of DNA immunization against human cytomegalovirus

Area of Science:

• Immunology
• Vaccinology
• Molecular Biology

Background:

• Human cytomegalovirus (HCMV) poses a significant health challenge, necessitating effective vaccine strategies.
• DNA vaccination offers a promising platform for inducing immune responses against viral pathogens like HCMV.
• Understanding the immunomodulatory effects of different vaccine constructs and delivery methods is crucial for optimizing vaccine efficacy.

Purpose of the Study:

• To analyze and compare the immune responses generated by different DNA vaccine constructs encoding HCMV antigens.
• To investigate the impact of delivery site multiplicity and antigen form (secreted vs. membrane-anchored) on antibody production.
• To evaluate the role of IFN-alpha co-expression and priming-boosting strategies in enhancing humoral and cellular immunity.

Main Methods:

• Mice were immunized with plasmids encoding human cytomegalovirus (HCMV) glycoprotein B (gB) or phosphoprotein 65 (pp65).
• Different inoculation strategies were employed, including single vs. multiple sites and various plasmid constructs (membrane-anchored vs. secreted gB).
• Immune responses, including antibody titers and cytotoxic T lymphocyte (CTL) activity, were measured.

Main Results:

• The secreted form of gB (pVR-gB Delta tm) elicited significantly higher antibody titers compared to the membrane-anchored form.
• Priming with pVR-gB Delta tm followed by boosting with gB subunit resulted in high-titer antibody responses.
• Immunization with VR-pp65 induced dose-dependent CTL responses in approximately 50% of mice.
• Co-expression of IFN-alpha showed a moderate increase in antibody response but did not affect CTL response rates.
• Multiple inoculation sites enhanced antibody response compared to a single site.

Conclusions:

• Optimizing DNA vaccine delivery, particularly using secreted antigens and multiple inoculation sites, can significantly enhance humoral immune responses against HCMV.
• The choice of antigen construct and immunization schedule (priming-boosting) is critical for achieving high-titer antibody responses.
• While IFN-alpha co-expression offers a moderate benefit, it does not substantially alter the overall immune response profile.
• These findings provide valuable insights for the development of more effective HCMV DNA vaccines targeting both antibody and cellular immunity.