Casey Thompson

Program: Molecular Microbiology and Microbial Pathogenesis

Current advisor: Sean P. J. Whelan, PhD

Undergraduate university: Colorado State University-Fort Collins, 2016

Enrollment year: 2019

Research summary
Host Factors Requisite in New World Arenavirus Entry

Arenaviruses are a group of zoonotic emerging pathogens that are considered a significant threat to human health globally. These viruses are enveloped, bisegmented, single-stranded, negative-sense RNA viruses that are divided into two geographically and serologically distinct groups: Old World (OW) and New World (NW). Arenavirus envelopes are decorated by their glycoproteins (GPC) that mediate viral entry and fusion. These viruses can zoonotically transmit to humans from their rodent hosts, where they can cause severe disease with case fatality rates up to 80%. Due to the high case fatality rates and the limited countermeasures available, arenaviruses that cause viral hemorrhagic fever are considered Category A pathogens and require study in a BSL4, subsequently hindering the ability to characterize the molecular mechanisms employed by these viruses. To combat this, researchers typically use apathogenic NW arenaviruses to study the molecular mechanisms of entry and infection due to their homology with pathogenic counterparts. However, these apathogenic NW arenaviruses can enter human cells independent of the known NW arenavirus receptor, human transferrin receptor 1 (hTfR1). To remedy these issues, we have developed the unique tool of chimeric vesicular stomatitis viruses (VSV) of which VSV’s glycoprotein (G) is replaced with NW GPCs of interest and therefore depend upon NW-GPC for infection. These chimeric VSVs allow us to study the mechanisms and host factors necessary for NW-GPC mediated entry in a BSL2. Like OW arenaviruses, NW arenaviruses bind to receptors at the cell surface and are then endocytosed and trafficked to late endosomes/lysosomes where the acidic pH required for fusion is located. Within the acidic pH of late endosomes/lysosomes OW arenaviruses undergo a pH-induced receptor switch which facilitates viral fusion. Despite the similarities to OW arenaviruses, no such endo/lysosomal host factors have been identified for NW arenaviruses. The central hypothesis of this study is that New World Arenaviruses utilize alternative host factors for hTfR1 independent entry and, like their OW counterparts, undergo a receptor switching mechanism to shared and unique endo/lysosomal host factors to facilitate membrane fusion. The unique chimeric VSV system coupled with CRISPR-Cas9 screening approaches have resulted in our identification of host factors for NW-GPC mediated infection that are shared with OW counterparts. Using genetic manipulation and biochemical approaches: Aim 1 expects to characterize these common host factors and define their role in viral fusion across the Arenaviridae family using a panel of chimeric VSV-NW-GPCs, while Aim 2 intends to identify and characterize alternative host factors necessary for hTfR1 independent viral entry. The information gained by this proposal will not only further the understanding of critical arenavirus biology but will also allow the comparison of common factors required throughout the viral species for arenavirus entry, generating a greater understanding of the requirements for zoonosis and elucidate potential novel therapeutic targets for NW arenaviruses.

Graduate publications
Doyle CA, Busey GW, Iobst WH, Kiessling V, Renken C, Doppalapudi H, Stremska ME, Manjegowda MC, Arish M, Wang W, Naphade S, Kennedy J, Bloyet LM, Thompson CE, Rothlauf PW, Stipes EJ, Whelan SPJ, Tamm LK, Kreutzberger AJB, Sun J, Desai BN. 2024 Endosomal fusion of pH-dependent enveloped viruses requires ion channel TRPM7. Nat Commun, 15(1):8479. PMCID: PMC11445543
PMC11445543

Pontelli MC, Castro IA, Martins RB, La Serra L, Veras FP, Nascimento DC, Silva CM, Cardoso RS, Rosales R, Gomes R, Lima TM, Souza JP, Vitti BC, Caetité DB, de Lima MHF, Stumpf SD, Thompson CE, Bloyet LM, Kawahisa JTE, Giannini MC, Bonjorno LP, Lopes MIF, Batah SS, Li S, Assad RL, Almeida SCL, Oliveira FR, Benatti MN, Pontes LLF, Santana RC, Vilar FC, Martins MA, Shi PY, Cunha TM, Calado RT, Alves-Filho JC, Zamboni DS, Fabro A, Louzada-Junior P, Oliveira RDR, Whelan SPJ, Cunha FQ, Arruda E.. 2022 SARS-CoV-2 productively infects primary human immune system cells in vitro and in COVID-19 patients. J Mol Cell Biol, ():mjac021. PMCID:

Walker FC, Hassan E, Peterson ST, Rodgers R, Schriefer LA, Thompson CE, Li Y, Kalugotla G, Blum-Johnston C, Lawrence D, McCune BT, Graziano VR, Lushniak L, Lee S, Roth AN, Karst SM, Nice TJ, Miner JJ, Wilen CB, Baldridge MT. 2021 Norovirus evolution in immunodeficient mice reveals potentiated pathogenicity via a single nucleotide change in the viral capsid. PLoS Pathog, 17(3):e100940. PMCID: PMC7987144

Mahoney M, Damalanka VC, Tartell MA, Chung DH, Lourenço AL, Pwee D, Mayer Bridwell AE, Hoffmann M, Voss J, Karmakar P, Azouz NP, Klingler AM, Rothlauf PW, Thompson CE, Lee M, Klampfer L, Stallings CL, Rothenberg ME, Pöhlmann S, Whelan SPJ, O’Donoghue AJ, Craik CS, Janetka JW. 2021 A novel class of TMPRSS2 inhibitors potently block SARS-CoV-2 and MERS-CoV viral entry and protect human epithelial lung cells. Proc Natl Acad Sci USA, 118(43):e2108728118. PMCID: PMC8694051