Browsing by Author "Lehman, Caitlin Woodson"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Attenuation of Programmed -1 Ribosomal Frameshifting in Venezuelan Equine Encephalitis Virus as a Vaccine Strategy
    Lehman, Caitlin Woodson; Lehman, Caitlin Woodson; Kehn-Hall, Kylene
    Venezuelan equine encephalitis virus (VEEV) is a New World alphavirus that is capable of causing significant disease in equines and humans. Moreover, infection with VEEV can be fatal in up to 90% of cases for equines. In humans, while death is rare, infection with VEEV can result in debilitating neurological sequelae. The current vaccines for VEEV are a live-attenuated vaccine (TC-83) and an inactivated form of the vaccine (C-84). However, neither of these are approved by the FDA for human use and only at risk military personnel and laboratorians are vaccinated. We are studying the rational design of VEEV vaccines through mutation of the programmed -1 ribosomal frameshifting (-1 PRF) signal of VEEV. Use of the -1 PRF signal allows production of the viral trans-frame protein of VEEV, which is known to play a role in neuropathogenesis. Our lab recently characterized the -1 PRF signals for alphaviruses and results revealed novel -1 PRF stimulatory structures. While disruption of the -1 PRF signal mildly affected VEEV kinetics in cell culture, it significantly inhibited its pathogenesis in mice challenged subcutaneously or via aerosol. In addition to markedly increased survival, mice exposed to the -1 PRF mutant VEEV (VEEV TrDPRFm) displayed less severe clinical signs and weight loss over the course of infection compared to wild-type (WT) control mice. Serial sacrifice studies indicated mice exposed to VEEV TrDPRFm had either undetectable or reduced levels of virus in the brain, spleen, and serum at all timepoints assayed indicating that dissemination of VEEV TrDPRFm is altered in vivo, resulting in less viral replication and overall decreased pathogenesis. Finally, mice vaccinated with VEEV TrDPRFm developed strong neutralizing antibodies and were protected against lethal challenge with aerosolized VEEV TrD. These studies indicate that targeting translational recoding events such as frameshifting is a potential avenue of inquiry for rational vaccine development.
  • Thumbnail Image
    Item
    EGR1 Upregulation During Encephalitic Viral Infections Contributes to Inflammation and Cell Death
    (2022) Lehman, Caitlin Woodson; Kehn-Hall, Kylene
    Early growth response 1 (EGR1) is an immediate early gene and transcription factor previously found to be significantly upregulated in human astrocytoma cells infected with Venezuelan equine encephalitis virus (VEEV). Loss of EGR1 resulted in decreased cell death, but had no significant impact on viral replication. Here, we extend these studies to determine the impacts of EGR1 on gene expression following viral infection in vitro and on animal survival and viral dissemination in vivo. Inflammatory genes CXCL3, CXCL8, and CXCL10 were found to be upregulated in VEEV infected cells in an EGR1 dependent manner. Additionally, other transcription factors, including EGR1 itself, as well as ATF3, FOS, JUN, EGR2, and EGR4 were found to be transcriptionally dependent on EGR1. We also examined EGR1’s transcriptional influence on gene expression in response to infection with other alphaviruses including eastern equine encephalitis virus (EEEV), Sindbis virus (SINV), and chikungunya virus (CHIKV), as well as Zika virus (ZIKV) and Rift Valley fever virus (RVFV), members of Flaviviridae and Phenuiviridae families, respectively. EGR1 was significantly upregulated to varying degrees in EEEV, CHIKV, RVFV, SINV and ZIKV, infected astrocytoma cells. Genes that were identified as being differentially upregulated following infection and also transcriptionally dependent on EGR1 included ATF3 (EEEV, CHIKV), JUN (EEEV), KLF4 (ZIKV, RVFV), CXCL3 (EEEV), CXCL8 (EEEV), CXCL10 (EEEV, RVFV), TNF-α (EEEV, ZIKV), and PTGS2 (EEEV). Additionally, inhibition of the inflammatory gene PTGS2 with Celecoxib, a small molecule inhibitor, rescued astrocytoma cells from VEEV induced cell death but had no impact on viral titers. Loss of EGR1 did not protect against VEEV induced mortality in vivo but EGR1-/- mice had delayed onset of clinical symptoms as well as delayed viral replication within the brain as compared to wild-type mice. Collectively, these results suggest that EGR1 induction following viral infection stimulates multiple inflammatory mediators. Managing inflammation and cell death in response to viral infection is of utmost importance, especially during VEEV infection where survivors are at-risk for neurological sequalae.