IMR Press / FBL / Volume 29 / Issue 3 / DOI: 10.31083/j.fbl2903102
Open Access Review
Impact of Toll-Like Receptors (TLRs) and TLR Signaling Proteins in Trigeminal Ganglia Impairing Herpes Simplex Virus 1 (HSV-1) Progression to Encephalitis: Insights from Mouse Models
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1 Imunologia de Doenças Virais, Instituto René Rachou, Fundação Oswaldo Cruz, 30190-002 Belo Horizonte, MG, Brazil
2 Departamento de Vigilância Sanitária, Secretaria Municipal de Saúde de Varginha, 37010-600 Varginha, MG, Brazil
3 Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas (ICB), Universidade Federal de Minas Gerais (UFMG), 31270-901 Belo Horizonte, MG, Brazil
*Correspondence: marco.campos@fiocruz.br (Marco Antônio Campos)
Front. Biosci. (Landmark Ed) 2024, 29(3), 102; https://doi.org/10.31083/j.fbl2903102
Submitted: 24 August 2023 | Revised: 7 December 2023 | Accepted: 2 January 2024 | Published: 14 March 2024
(This article belongs to the Special Issue Toll-Like Receptors in Various Pathologies)
Copyright: © 2024 The Author(s). Published by IMR Press.
This is an open access article under the CC BY 4.0 license.
Abstract

Herpes simplex virus 1 (HSV-1) or simplexvirus humanalpha 1 is a neurotropic virus that is responsible for orofacial infections in humans. More than 70% of the world’s population may have seropositivity for HSV-1, and this virus is a leading cause of sporadic lethal encephalitis in humans. The role of toll-like receptors (TLRs) in defending against HSV-1 infection has been explored, including the consequences of lacking these receptors or other proteins in the TLR pathway. Cell and mouse models have been used to study the importance of these receptors in combating HSV-1, how they relate to the innate immune response, and how they participate in the orchestration of the adaptive immune response. Myeloid differentiation factor 88 (MyD88) is a protein involved in the downstream activation of TLRs and plays a crucial role in this signaling. Mice with functional MyD88 or TLR2 and TLR9 can survive HSV-1 infection. However, they can develop encephalitis and face a 100% mortality rate in a dose-dependent manner when MyD88 or TLR2 plus TLR9 proteins are non-functional. In TLR2/9 knockout mice, an increase in chemokines and decreases in nitric oxide (NO), interferon (IFN) gamma, and interleukin 1 (IL-1) levels in the trigeminal ganglia (TG) have been correlated with mortality.

Keywords
HSV-1
TLR-induced immune response
encephalitis
defective TLR
innate immunity
Funding
IRR-009-FEX 23, PPE 00040/22/Fundação de Amparo à Pesquisa do Estado de Minas Gerais
310928/2021-4/Conselho Nacional de Desenvolvimento Científico e Tecnológico
315750/2020-0/Conselho Nacional de Desenvolvimento Científico e Tecnológico
Figures
Fig. 1.
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