Herpes simplex virus 1 interaction with Toll-like receptor 2 contributes to lethal encephalitis

Area of Science:

• Immunology
• Virology
• Neonatal Infections

Background:

• Herpes simplex virus 1 (HSV-1) causes diverse infections in neonates, ranging from localized skin/eye/mouth disease to severe CNS or disseminated infections.
• The pathogenesis of severe HSV-1 in neonates involves inflammatory cytokines, with Toll-like receptors (TLRs) implicated in their induction.
• TLRs are crucial for host defense, recognizing pathogen components and triggering inflammatory responses.

Purpose of the Study:

• To investigate the role of TLR2 in mediating the inflammatory cytokine response to HSV-1 infection.
• To determine the impact of TLR2 deficiency on the host's response to HSV-1, including mortality and brain inflammation.

Main Methods:

• Utilized transfected cell lines and TLR2 knockout (TLR2(-/-)) mice to study HSV-1 infection.
• Compared cytokine levels, brain inflammation markers (monocyte chemoattractant protein 1), and mortality rates in TLR2(-/-) mice versus wild-type and TLR4(-/-) mice.

Main Results:

• HSV-1 induced a blunted cytokine response in TLR2(-/-) mice.
• TLR2(-/-) mice exhibited significantly lower brain levels of monocyte chemoattractant protein 1 compared to wild-type and TLR4(-/-) mice.
• Mortality was reduced in TLR2(-/-) mice, with no significant differences in virus levels observed.

Conclusions:

• TLR2 plays a critical role in mediating the inflammatory cytokine response to HSV-1.
• The TLR2-mediated cytokine response to HSV-1 appears detrimental to the host, contributing to increased mortality and brain inflammation.
• Targeting TLR2 may offer a therapeutic strategy for managing severe HSV-1 infections in neonates.