UBC Theses and Dissertations
Prevention of respiratory syncytial virus infection via methoxypoly(ethylene glycol)-modification of the virus or its host cell Sutton, Troy Clavell
Respiratory Syncytial Virus (RSV) causes significant morbidity and mortality in humans. To date, no vaccines or effective treatments exist for this serious respiratory disease. Current prophylactic therapy is limited to at-risk neonates due to its high cost, and involves the administration of anti-RSV immune globulins that are 5O% effective. To attenuate or inhibit RSV infection, we hypothesized that bioengineering of either the virus particle or host cell with methoxypoly(ethylene glycol) [mPEG] would prevent viral infection. Our specific objectives were to evaluate the effects of grafting concentration, linker chemistry, polymer length, and cell polarization on viral infection and propagation. Modification of either the virus or host cells with mPEG prevented RSV infection in a dose- and size-dependent maimer. For virus modification, short chain polymers (2 kDa) were significantly more effective than long chain polymers (20 kDa). For example, plaque assays demonstrated that RSV modification with 5 mM, 2 or 20 kDa mPEG resulted in a 100 and -82% plaque reduction, respectively. In contrast, when small polymers were used to modify the host cell they provided no protection, while long chain polymers effectively prevented infection. For example, at 48 hours post-infection at a multiplicity of infection of 0.5 and grafting concentrations of 5, 7.5, and 15 mM, 20 kDa mPEG decreased infection by 45, 83, and 91%, respectively. However, these grafting concentrations of the 2 kDa mPEG resulted in 0% reduction. Importantly, with both viral and host cell PEGylation strategies, moderate to high grafting concentrations of the appropriate polymer species were able to provide near complete protection against infection in both non-polarized and polarized cells. In conclusion, mPEG-modification of RSV or the host cell are highly effective methods for preventing viral infection. Our findings indicate that the length of grafted polymer must be matched to the size of particle targeted for modification. Consequent to the high efficacy of both PEGylation approaches, future studies should evaluate mPEG-modified RSV as a vaccine strategy, and mPEG-grafting to the nasal epithelium as a prophylactic therapy.
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