Prunella vulgaris polysaccharide inhibits herpes simplex virus infection by blocking TLR-mediated NF-κB activation

Xuanlei Zhong; Yibo Zhang; Man Yuan; Lin Xu; Xiaomei Luo; Rong Wu; Zhichao Xi; Yang Li; Hongxi Xu

doi:10.1186/s13020-023-00865-y

Prunella vulgaris polysaccharide inhibits herpes simplex virus infection by blocking TLR-mediated NF-κB activation

Chin Med. 2024 Jan 8;19(1):6. doi: 10.1186/s13020-023-00865-y.

Authors

Xuanlei Zhong^#^{1

2}, Yibo Zhang^#^{1

2}, Man Yuan^#^{1

2}, Lin Xu^{1

2}, Xiaomei Luo^{1

2}, Rong Wu^{1

2}, Zhichao Xi^{1

2}, Yang Li^{3

4}, Hongxi Xu⁵

Affiliations

¹ School of Pharmacy, Shanghai University of Traditional Chinese Medicine, No. 1200, Cailun Road, Shanghai, 201203, China.
² Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai, China.
³ School of Pharmacy, Shanghai University of Traditional Chinese Medicine, No. 1200, Cailun Road, Shanghai, 201203, China. yangl@shutcm.edu.cn.
⁴ Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai, China. yangl@shutcm.edu.cn.
⁵ Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China. hxxu@shutcm.edu.cn.

^# Contributed equally.

Abstract

Background: Prunella vulgaris polysaccharide extracted by hot water and 30% ethanol precipitation (PVE30) was reported to possess potent antiviral effects against herpes simplex virus (HSV) infection. However, its anti-HSV mechanism has not yet been fully elucidated.

Purpose: This study aimed to investigate the potential mechanisms of PVE30 against HSV infection.

Methods: Antiviral activity was evaluated by a plaque reduction assay, and the EC₅₀ value was calculated. Immunofluorescence staining and heparin bead pull-down assays confirmed the interactions between PVE30 and viral glycoproteins. Real-time PCR was conducted to determine the mRNA levels of viral genes, including UL54, UL29, UL27, UL44, and US6, and the proinflammatory cytokines IL-6 and TNF-α. The protein expression of viral proteins (ICP27, ICP8, gB, gC, and gD), the activity of the TLR-NF-κB signalling pathway, and necroptotic-associated proteins were evaluated by Western blotting. The proportion of necroptotic cells was determined by flow cytometric analysis.

Results: The P. vulgaris polysaccharide PVE30 was shown to compete with heparan sulfate for interaction with HSV surface glycoprotein B and gC, thus strongly inhibiting HSV attachment to cells. In addition, PVE30 downregulated the expression of IE genes, which subsequently downregulated the expression of E and L viral gene products, and thus effectively restricted the yield of progeny virus. Further investigation confirmed that PVE30 inhibited TLR2 and TLR3 signalling, leading to the effective suppression of NF-κB activation and IL-6 and TNF-α expression levels, and blocked HSV-1-induced necroptosis by reducing HSV-1-induced phosphorylation of MLKL.

Conclusion: Our results demonstrate that the P. vulgaris polysaccharide PVE30 is a potent anti-HSV agent that blocks TLR-mediated NF-κB activation.

Keywords: Herpes simplex virus; Necroptosis; Prunella vulgaris polysaccharide; TLR/NF-κB signalling pathway.

Abstract

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