Exploiting viral natural history for vaccine development

Area of Science:

• Virology
• Immunology
• Vaccine Development

Background:

• Human cytomegalovirus (HCMV) infection is a significant health concern, particularly for immunocompromised individuals and in congenital cases.
• Existing vaccine strategies targeting HCMV, such as those based on the glycoprotein B (gB), have shown partial success but are insufficient for complete protection.
• HCMV possesses a complex lifecycle and remarkable ability to persist lifelong and reinfect individuals, underscoring the need for advanced vaccine approaches.

Purpose of the Study:

• To evaluate the limitations of current HCMV vaccine strategies and identify alternative targets for improved efficacy.
• To explore the potential of targeting the gH/gL pentameric complex (gH/gL-PC) involved in HCMV entry into epithelial and endothelial cells.
• To propose a novel vaccine strategy focusing on HCMV immune-modulating proteins based on its natural history and pathogenesis.

Main Methods:

• Review of existing Phase 2 gB-based vaccine trial data for HCMV.
• Analysis of the HCMV lifecycle, focusing on the roles of the gB and gH/gL-PC in viral entry and spread.
• Examination of HCMV's natural history, including lifelong persistence and reinfection capabilities.
• Consideration of viral proteins that modulate host cell functions as potential vaccine targets.

Main Results:

• Antibodies neutralizing the HCMV fusion pathway via gB are not sufficient for protective immunity.
• The gH/gL-PC is a promising target for neutralizing HCMV entry into critical epithelial and endothelial cells.
• HCMV's ability to persist and reinfect is linked to its extensive repertoire of immune-modulating proteins.

Conclusions:

• Novel HCMV vaccine strategies must complement existing approaches by targeting different aspects of the viral lifecycle.
• The gH/gL-PC represents a valuable target for interrupting HCMV infection, particularly during primary mucosal infection.
• Targeting HCMV's immune-modulating proteins, which are key to its persistence and immune evasion, offers a promising avenue for developing a more effective vaccine.