LOW-COST LATERAL FLOW ASSAY PLATFORM FOR RAPID POINT-OF-CARE DETECTION OF FOODBORNE VIRUSES IN QATAR

Abstract

Norovirus (NoV), Hepatitis E Virus (HEV), and Hepatitis A Virus (HAV) are major causes of viral gastroenteritis and hepatitis, posing global public health challenges. These infections are particularly concerning in regions with high population mobility and varying sanitation standards, such as Qatar, where a large migrant workforce lives in high-density accommodations. Rapid, sensitive, and cost-effective diagnostics are critical for early detection, outbreak control, and epidemiological surveillance. This dissertation addresses these challenges by developing novel lateral flow assays (LFIAs) for NoV and HEV detection, while establishing the groundwork for future HAV LFIA development. A systematic review and meta-analysis were conducted to assess NoV prevalence and genotypic diversity in the Middle East and North Africa (MENA). The pooled NoV prevalence was 13.5%, with genotype GII.4 identified as the dominant strain. Complementing this, a large-scale seroprevalence study in Qatar's craft and manual worker (CMW) population revealed a high HEV burden (27.3%), with significant variation by nationality and occupational exposure. HAV seroprevalence exceeded 90%, indicating early-life exposure in highly endemic regions. These findings emphasize the need for improved diagnostic tools to support public health interventions. This dissertation presents the development of two highly sensitive LFIAs tailored for point-of-care (POC) testing. The NoV LFIA (NorTest), using europium nanoparticles and a portable Cube reader, demonstrated 96.2% sensitivity and 100% specificity-exceeding the performance of commercial antigen assays. The HEV LFIA, based on gold nanoparticles, achieved a 10 ng/mL detection limit, making it one of the most sensitive HEV rapid tests to date. Extensive antibody screening, buffer optimization, and clinical validation ensured high reproducibility and accuracy. By integrating advanced nanomaterials and optimized immunochemistry, this work advances low-cost, scalable LFIA platforms for enteric virus detection. NorTest is currently being transitioned from lab validation to large-scale production and registration in partnership with Qatari German Medical Devices Co., aiming for approval as a Class II medical device under Qatar's Ministry of Public Health. This research contributes significantly to Qatar's diagnostic capabilities and global surveillance efforts, demonstrating the transformative potential of LFIA technology in managing emerging viral threats.