Science Bite (3 minute oral presentation with PPT in live session and poster) - Students and ECRs only 14th Lorne Infection and Immunity 2024

Molecular and cellular pathogenesis of Ross River virus (#42)

Nicholas Yuen 1 , Melodie Eng 1 , Nicholas Hudson 2 , Albert Sole-Guitart 1 , Mitchell Coyle 3 , Helle Bielefeldt-Ohmann 4 5
  1. School of Veterinary Science, The University of Queensland, Gatton, QLD, Australia
  2. School of Agriculture and Food Sustainability, The University of Queensland, Gatton, QLD, Australia
  3. Equine Unit, Office of the Director Gatton Campus, The University of Queensland, Gatton, QLD, Australia
  4. School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, Australia
  5. Australian Infectious Diseases Research Centre, The University of Queensland, St. Lucia, QLD, Australia

Introduction

Ross River virus (RRV) has for decades been recognized as the most prevalent arbovirus infection in Australia and identified as an emerging infectious disease worldwide. Infected humans and horses experience acute febrile illness with joint pain being the most common clinical sign. Around 50% of symptomatic individuals experience chronic debilitating symptoms which can last for > 12 months. However, our understanding of RRV pathogenesis in human and horses remains unclear.

 

Methods

We established a horse model for the study of RRV pathogenesis in a naturally susceptible host. Peripheral blood mononuclear cells (PBMC), primary synovial fibroblasts and epidermal keratinocytes were infected in vitro with RRV at a MOI (multiplicity of infection) of 1, 3, and 800, respectively. RNA sequencing, metabolic flux analysis, virus growth kinetics and immunohistochemistry were performed to elucidate the molecular and cellular functional immune responses of these cell types upon RRV infection.

 

Results

Transcriptomic analysis revealed that transcription of mxra8, a recently discovered molecule responsible for RRV cell entry, was significantly downregulated in all cell types following infection with RRV, while potent antiviral and inflammatory responses were generated by these cells upon RRV infection. Significant upregulation of tlr3, but not tlr7,8,9, was seen in all infected cells suggestive of RRV abortive replication or immune evasion. Cells infected with RRV had reduced mitochondrial functions as evident by insignificant expression of mavs despite transcriptional upregulation of rig1 and mda5, and a reduction in oxygen consumption capacity in infected PBMC and fibroblasts. RRV antigens were undetectable by immunohistochemistry in monocytes-derived macrophages and keratinocytes infected with RRV. Virus growth kinetic studies revealed inefficient virus replication in fibroblasts and keratinocytes.

 

Conclusion

By using multi-modal analyses using a relevant host model system, this study revealed previously unexplored molecular and functional mechanisms of RRV immuno-pathogenesis.