Herpes Simplex Virus 1 Specifically Targets Human CD1d Antigen Presentation To Enhance Its Pathogenicity

Area of Science:

• Immunology
• Virology
• Infectious Diseases

Background:

• Herpes simplex virus 1 (HSV-1) is a common human pathogen with partially understood immune evasion mechanisms.
• CD1d-restricted NKT cells are crucial for innate immunity against infections and tumors.
• HSV-1 infection leads to downregulation of CD1d and suppression of NKT cell function.

Purpose of the Study:

• To investigate how HSV-1 interacts with the host immune system, specifically NKT cells.
• To identify viral factors responsible for suppressing NKT cell function.
• To explore the role of CD1d-humanized mice in studying HSV-1 pathogenesis and immune evasion.

Main Methods:

• Utilized CD1d-humanized mice (hCD1d knock-in mice) for in vivo infection studies.
• Investigated the role of the viral serine/threonine protein kinase US3 in CD1d modulation.
• Compared infection efficiency in hCD1d knock-in mice versus mice lacking NKT cells.

Main Results:

• HSV-1 efficiently downregulates human CD1d (hCD1d) and suppresses NKT cell function, unlike its effect on mouse CD1d.
• The viral protein US3 is identified as a key factor in HSV-1's suppression of hCD1d.
• HSV-1 establishes infection more efficiently in hCD1d knock-in mice, indicating successful immune evasion.
• US3-deficient viruses show reduced infectivity in hCD1d knock-in mice but higher infectivity in NKT cell-deficient mice.

Conclusions:

• HSV-1 has coevolved to specifically evade the human CD1d-NKT cell axis, representing a significant pathogenic factor.
• NKT cells play a potent role in anti-HSV immune responses.
• NKT cell ligands hold potential as adjuvants for developing future HSV vaccines.