PERK Is Critical for Alphavirus Nonstructural Protein Translation

Bibha Dahal,Nicole R Bracci,Kylene Kehn-Hall,Jonathan D Dinman,Jonathan L Jacobs,Lauren Panny,Ivan Akhrymuk,Caitlin W Lehman,Nishank Bhalla,Michael D Barrera

doi:10.3390/v13050892

Abstract

Venezuelan equine encephalitis virus (VEEV) is an alphavirus that causes encephalitis. Previous work indicated that VEEV infection induced early growth response 1 (EGR1) expression, leading to cell death via the protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) arm of the unfolded protein response (UPR) pathway. Loss of PERK prevented EGR1 induction and decreased VEEV-induced death. The results presented within show that loss of PERK in human primary astrocytes dramatically reduced VEEV and eastern equine encephalitis virus (EEEV) infectious titers by 4–5 log10. Loss of PERK also suppressed VEEV replication in primary human pericytes and human umbilical vein endothelial cells, but it had no impact on VEEV replication in transformed U87MG and 293T cells. A significant reduction in VEEV RNA levels was observed as early as 3 h post-infection, but viral entry assays indicated that the loss of PERK minimally impacted VEEV entry. In contrast, the loss of PERK resulted in a dramatic reduction in viral nonstructural protein translation and negative-strand viral RNA production. The loss of PERK also reduced the production of Rift Valley fever virus and Zika virus infectious titers. These data indicate that PERK is an essential factor for the translation of alphavirus nonstructural proteins and impacts multiple RNA viruses, making it an exciting target for antiviral development.

Highlights

Venezuelan equine encephalitis virus (VEEV) is an alphavirus that causes significant disease in humans and equines, affecting the central nervous system (CNS), which often results in neuropathology
Our previous work showed that siRNA-mediated depletion of PERK in human primary astrocytes resulted in a ≈ 5-log10 reduction of VEEV RNA [5]
Cells were transfected with siRNA targeting PERK or a negative control siRNA for 48 h and infected with VEEV (MOI 5)

Summary

Introduction

Venezuelan equine encephalitis virus (VEEV) is an alphavirus that causes significant disease in humans and equines, affecting the central nervous system (CNS), which often results in neuropathology. VEEV causes febrile illness characterized by fever, malaise, and vomiting. Infection can progress to the CNS, causing neurological symptoms, including confusion, ataxia, and seizures. Encephalitis develops in approximately 4% of cases with an overall mortality of 1–2% [1,2,3]. There are no FDA-approved therapeutics or vaccines available for the treatment and prevention of VEEV-induced disease in humans. It is imperative to understand host–pathogen interactions that could be exploited as novel targets for therapeutics

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