Oncolytic Virotherapy Reovirus: A Prototypical Wild-type Oncolytic Virus By: Stephen Mayper

Cancer Abnormal cell growth Accumulated genetic & epigenetic alterations Healthy cells gone “haywire” Numerous means of immune response evasion

Conventional Treatments Surgery Tumor removal Is ineffective against and can induce metastasis Inherent risk!

Conventional Treatments Radiotherapy Uses radiation to kill tumor cells Effective at reducing… …Tumors! …Aaaaand healthy cells Can carry severe side effects (Creative representation if innocent bystander cell death…)

Conventional Treatments Chemotherapy Use of pharmaceuticals to kill tumor cells It works! …But it kills lots of other cells indiscriminately

Emerging Treatment: Virotherapy Uses an oncolytic virus (OV) to lyse cancer cells Advantages: High specificity means fewer side effects Self-regulating dosage Lack of contraindications

Viruses currently being explored SV40 virus Seneca Valley virus Adenovirus Parvo virus Myxoma virus Mumps virus Influenza virus Human Herpes virus Pseudorabies virus Vaccinia virus Coxsackie A virus

How does it work? …Get it? Virus can be… Naturally occurring (It’s a virus in “nature!”) Virus can be… Naturally occurring Genetically engineered Transcription targeting Attenuation Specificity generally determined by antiviral pathway deregulation

Example: Adenovirus Therapy Targeting Gliomas Source: Maruniak, Jim. "Adenovirus." MCB 5505, Honors Virology. University of Florida, Gainesville, FL. 19 Feb. 2011. Lecture.

Another Mechanism of Tumor Cell OV Susceptibility Source: Chiocca EA. Oncolytic viruses. Nat Rev Cancer. 2002 Dec;2(12):938-50.

Reovirus

Reovirus Background REOvirus = “Respiratory Enteric Orphan Virus” Infect human respiratory & gastrointestinal tracts “Orphaned” because originally not thought to be associated with any disease Several disease associations discovered since Reoviruses are pervasive

Reovirus Taxonomy Mostly Asymptomatic African Horse Sickness Family: Reoviridae Genera Infecting Vertebrates (6) Orthoreovirus Orbivirus Coltivirus Rotavirus Aquareovirus Seadornavirus African Horse Sickness Colorado Tick Fever Blue Tongue Disease Mostly Asymptomatic (Percentage of gastroenteritis deaths) Source: Cann, Alan. "Reoviruses." MicrobiologyBytes. 11 Sept. 2007. Web. <http://www.microbiologybytes.com/virology/Reoviruses.html>.

Reovirus Structure Spherical, 80 nm diameter Non-enveloped Isometric capsid Concentric inner and outer capsids Sometimes middle capsid (Inner capsid = “core”) 4 core proteins λ-1, λ-3, μ-2, σ-2 Heat-stable Stable @ pH= 3 – 9 Denatured by ethanol

Reovirus Genome RNA Double- Stranded Linear 10-12 segments (species- dependent) Reassortment common in vitro Encodes viral replication machinery Source: http://education.expasy.org/images/Orthoreovirus_genome.jpg

Reovirus Reproduction Replicates in the cytoplasm Encodes its own replication machinery Antiviral susceptibility Does NOT fully uncoat Core is resistant to protease digestion No uncoating No destruction by host cell Genomic RNA stays in the core Assembled virions form cytoplasmic inclusion bodies Released via cell lysis 6 – 7 hour replication time

Reovirus Replication Illustrated

Questions? Comments?

Sources Cann, Alan. "Reoviruses." MicrobiologyBytes. 11 Sept. 2007. Web. <http://www.microbiologybytes.com/virology/Reoviruses.html>. Chiocca EA. Oncolytic viruses. Nat Rev Cancer. 2002 Dec;2(12):938-50. Hammill AM, Conner J, Cripe TP. Oncolytic virotherapy reaches adolescence. Pediatr Blood Cancer. 2010 Dec 15;55(7):1253-63. doi: 10.1002/pbc.22724. Epub 2010 Aug 23. Maruniak, Jim. "Adenovirus." MCB 5505, Honors Virology. University of Florida, Gainesville, FL. 19 Feb. 2011. Lecture. Mertens P. The dsRNA viruses. Virus Res. 2004 Apr;101(1):3-13. Nettelbeck DM. Cellular genetic tools to control oncolytic adenoviruses for virotherapy of cancer. J Mol Med. 2008 Apr;86(4):363-77. Epub 2007 Dec 19. Siegel, Robert. "Reoviruses." Stanford University. 1 Feb. 1999. Web. 20 Apr. 2011. <http://www.stanford.edu/group/virus/1999/caryn/reovirus.html>. Vähä-Koskela MJ, Heikkilä JE, Hinkkanen AE. Oncolytic viruses in cancer therapy. Cancer Lett. 2007 Sep 8;254(2):178-216. Epub 2007 Mar 23.