Date of Award

12-16-2020

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

Suri S. Iyer

Abstract

This thesis focuses on the development of assays that could potentially be used in Point-Of-Care (POC) diagnostics. We present our discovery and development efforts for three targets, influenza, norovirus and inflammatory bowel disease.

Influenza is a respiratory infection caused by influenza viruses, a highly contagious pathogen that primarily spreads through respiratory droplets. Influenza pandemics has led to millions of deaths. A significant number of patients have complications because of secondary infections caused by S. pneumoniae, after the initial infection caused by influenza. Thus, differentiation of influenza and S. pneumoniae is very important for appropriate treatment options. Here, we have synthesized fluorescent sialic acid derivatives that are cleaved by influenza neuraminidases (NAs) and not by S. pneumoniae. We have also developed assays that could differentiate between influenza viruses and S. pneumoniae by taking advantage of the structural differences between NAs from these pathogens and assay conditions.

In the second project, we present our efforts to identify and develop biomarkers for inflammatory bowel disease (IBD), which is characterized by chronic inflammation in gastrointestinal tract. People diagnosed with IBD are required to monitor their status of inflammation routinely. The gold standard to monitor IBD is to perform endoscopic evaluation with biopsies. However, this method is invasive, and patients often experience pain and discomfort during these procedures, highlighting the need for a non-invasive and cost-effective technique to monitor inflammation. Here, we explore the use of alternate biomarkers, matrix metallopeptidase 9 (MMP-9) and tumor necrosis factor alpha (TNF-α) in stool and sera, respectively, that can increase in inflammatory conditions. We explored the correlation between MMP-9, TNF-α levels and severity of colitis in IL10-/- mouse model, with a view to designing an effective tool for POC diagnostics for human IBD, since IL10-/- mouse model reflects inflammation in human IBD patients. We also present our initial studies to detect and monitor these biomarkers using a novel mesoporous silica bead-based method.

In the third project, we targeted human noroviruses in an effort to develop assays that could detect noroviruses at POC. Human noroviruses are the major cause of epidemic outbreaks of gastroenteritis. At the present time, there are no antivirals or vaccine for norovirus infection; the treatment options are primarily supportive care, and reverse dehydration and electrolyte abnormality. Therefore, prevention and early diagnostics of norovirus is important. When noroviruses infect humans, it binds to human histo-blood group antigens (HBGAs). However, the interactions between norovirus and HBGAs are poorly understood. Here, we have studied the interactions between norovirus virus like particles (VLPs) and chemically synthesized HBGAs by surface plasmon resonance (SPR) with the ultimate goal being able to use some of these carbohydrates as recognition molecules in diagnostics to capture norovirus. We found that the interactions between HBGA and VLPs are complex and highly dependent on the structure of the VLP and the carbohydrate.

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