Gram-positive bacterial cell wall components inhibit herpes simplex virus infection.

Area of Science:

• Microbiology
• Immunology
• Virology

Background:

• The role of the mucosal microbiome in viral infections is not fully understood.
• Genital herpes (HSV-1 and HSV-2) is a prevalent sexually transmitted infection.
• Vaginal *Lactobacillus* is linked to protection against sexually transmitted viruses, but mechanisms are unclear.

Purpose of the Study:

• To investigate the antiviral properties of gram-positive bacterial cell wall components against HSV.
• To explore the role of the mucosal microbiome in genital herpes infection.

Main Methods:

• *In vitro* studies using cell cultures to assess HSV infectivity.
• Mouse models of genital herpes infection to evaluate disease outcomes.
• Analysis of bacterial cell wall components like peptidoglycan (PG) and lipoteichoic acid (LTA).
• Investigation of *Lactobacillus crispatus* surface layer proteins (SlpA, SlpB) binding to HSV-1.

Main Results:

• Gram-positive bacterial cell wall components (PG, LTA) significantly inhibited HSV-1 and HSV-2 infectivity *in vitro*.
• These components improved survival and disease outcomes in a mouse model of genital herpes.
• *Lactobacillus crispatus* SlpA and SlpB bind HSV-1 and inhibit infection.
• Antiviral effects were dose-dependent, required intact PG structure, and were independent of TLR2 signaling for PG and LTA.

Conclusions:

• Gram-positive bacterial cell wall components possess a species-independent antiviral function against HSV.
• The composition of the mucosal microbiome may play a significant role in suppressing mucosal herpes infections.