The effects of the human innate pattern recognition receptor L-ficolin and its variants against Hepatitis C virus infection

Mason, Christopher Paul (2019) The effects of the human innate pattern recognition receptor L-ficolin and its variants against Hepatitis C virus infection. PhD thesis, University of Nottingham.

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Enveloped virus infections have major impacts to global health and economy. For example, Hepatitis C virus is a leading cause of chronic hepatic disease, and the 2013 Ebola virus outbreak highlighted the need for broadly-active treatments. The immune factors behind successful control of these infections are poorly understood. A potential common target for intervention is the glycosylation patterns that decorate the surface proteins of enveloped virions.

L-ficolin is a liver-expressed lectin that binds several diverse enveloped viruses via their glycosylated surface envelope proteins, and contributes to the innate immune response through blocking of viral entry and complement activation. Two mutations, Thr236Met and Ala258Ser, in L-ficolin are maintained in human populations at high frequencies and influence ligand binding, serum L-ficolin concentration, and response to microbial infection.

In this study, expression of recombinant His6-tagged L-ficolin was optimised. It was hypothesised that L-ficolin mutants described above have superior ligand binding and antiviral properties. The T236M mutation conferred increased binding of acetylated BSA. In an associated study, L-ficolin was used as an oligomeric scaffold for presenting anti-HCV nanobodies. This novel chimaeric molecule, named ficobody, exhibited superior ligand- and HCV glycoprotein-binding activity when compared to L-ficolin. This is the first instance in which lectins have been used as a scaffold for protein presentation.

Furthermore, correlations between serum L-ficolin concentrations and HCV infection outcome and ethnicity were investigated, finding that chronic HCV patients had significantly lower L-ficolin concentrations. Finally, mutant viruses were used to explore if specific glycosylation sites on the HCV glycoproteins are essential for L-ficolin interaction, producing data that supported previous findings on the roles of specific glycosylation sites in HCV entry.

Understanding the antiviral significance of L-ficolin variants could inform the use of L-ficolin and ficobody in the prognosis, prophylaxis and treatment of a wide variety of enveloped virus infections.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Tarr, Alexander
Ball, Jonathan
Keywords: Microbiology; Immunology; Virology; L-Ficolin; Virus; Innate Immune System; Hepatitis C Virus; Ebola Virus
Subjects: Q Science > QR Microbiology
Faculties/Schools: UK Campuses > Faculty of Medicine and Health Sciences > School of Life Sciences
Item ID: 56745
Depositing User: Mason, Christopher
Date Deposited: 04 Sep 2019 12:51
Last Modified: 19 Jul 2021 04:30

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