Finding NEMO by the molluscum contagiosum virus MC159 protein and its effect on viral pathogenesis in vivo

Biswas, Sunetra

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Description

Title

Finding NEMO by the molluscum contagiosum virus MC159 protein and its effect on viral pathogenesis in vivo

Author(s)

Biswas, Sunetra

Issue Date

2017-12-08

Director of Research (if dissertation) or Advisor (if thesis)

Shisler, Joanna L.

Doctoral Committee Chair(s)

Shisler, Joanna L.

Committee Member(s)

• Wilson, Brenda A.
• Blanke, Steven R.
• Slauch, James M.

Department of Study

Microbiology

Discipline

Microbiology

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• NF-κB essential modulator (NEMO)
• Molluscumcontagiosum virus (MCV)
• NF-kappaB
• MC159
• MC160
• cIAP1
• Polyubiquitination
• Virus
• Genotoxic stress

Abstract

Molluscum contagiosum virus (MCV) is a dermatotropic poxvirus that solely infects humans. MCV infections causes benign neoplastic lesions that can persists for few months in children and adults. It is an opportunistic infection in immunocompromised patients. Currently there is no FDA approved drug available for MCV infections. The knowledge of MCV pathogenesis is rudimentary because there is no proper system of propagation nor an animal model to study MCV during infection. The proinflammatory cytokine Tumor Necrosis Factor (TNF) is highly expressed in MCV lesions and surrounding tissues. Interestingly, MCV causes little to no inflammation despite the expression of proinflammatory cytokines. This is because MCV encodes immunomodulatory proteins like MC159 protein to antagonize/neutralize TNF and other aspects of the proinflammatory immune response. For example, the MCV MC159 protein suppresses NF-kB activation, a powerful anti-viral response, via interactions with the NEMO subunit of the IKK complex. The exact molecular mechanism that inhibited IKK and NF-kB activation remained unknown and the work presented here identifies this mechanism. Briefly, I found that MC159 antagonizes cIAP1-NEMO interactions to inhibit NEMO polyubiquitination and thus NF-kB activation. This is a novel finding of a viral protein to disrupt NEMO-cIAP1 interactions to strategically suppress IKK activation (Chapter II). I also found that MC159 can inhibit NF-kB activation triggered by genotoxic stress. This signal transduction pathway has some unique features that are missing during TNF-induced NF-kB activation. I used mutational analysis of MC159 to identify that there are some regions of MC159 that are important for protecting against genotoxic-stress induced NF-kB activation but not TNF-induced NF-kB activation (Chapter IV). The importance of MC159 and its homolog MC160 during MCV infection has remained unknown, as there is no standard tissue culture for propagation or an animal model of infection. All of the functions of MC159 and MC160 were identified by expressing MC159 independent of infection. To bridge this gap in knowledge, I investigated if a surrogate virus (vaccinia virus), lacking an inhibitor of NF-kB (DA49), could be used to study the functions of MCV proteins during vaccinia virus infections in mice. We created two recombinant vaccinia viruses, vMC159 and vMC160 expressing MC159L and MC160L genes, respectively. My hypothesis was that MC159 and MC160 would functionally substitute for A49 and restore the virulence of the virus (vDA49). I found that vMC159 functions in vivo was most striking as it was less virulent in both intranasal (IN) and intradermal (ID) route of inoculation. In the ID model of infection, vMC159 did not form any lesions in vMC159-infected ear pinnae in spite of harboring infectious vMC159 particles 11 days post-infection. Thus, this approach provides, for the first time, an examination of how MCV proteins may aid in virus virulence within the context of a complete and complex immune system (Chapter III).

Graduation Semester

2017-12

Type of Resource

text

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Copyright and License Information

Copyright 2017 Sunetra Biswas

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