Antigen tests

Ph.D. Lateral flow assays to diagnose tropical viruses.

My Ph.D. thesis work focused on the diagnosis of viral haemorrhagic fever viruses. In particular, dengue is a major international health concern because its dissemination has increased greatly in urban areas due to travel and globalization. The WHO estimates that there are 50-100 million infections yearly, and 2.5 billion people at risk of dengue. There are four distinct viral serotypes (DEN 1-4). Subsequent infections by different serotypes increase the risk of developing dengue haemorrhagic fever (DHF) or dengue shock syndrome (DSS).

Accurate diagnosis of dengue fever is critical to treat individual patients and to predict the potential of epidemics resulting from the introduction of a dengue serotype previously unknown to an area. The current methods for dengue detection include thermal cycling amplification (PCR) and enzyme-linked immunoabsorbent assays (ELISA). However, these methods require specialized equipment, reagents, and highly trained personnel, have a complex methodology, and a slow turnaround for readout, challenging their suitability in the field. Immunochromatography assays, also known as lateral flow tests, on the other hand, are simple, easy to use, low-cost diagnostic tools that provide fast detection of antibodies or antigens. They rely on the accumulation of gold nanoparticles that form a visible band when a test protein is present in solution. Therefore, gold nanoparticle conjugates and the antibodies used to detect the disease biomarkers are critical to ensure that lateral flow devices have enough sensitivity to detect disease even at low concentrations of target protein, such as in early stages of the disease.

My thesis project focused on improving the nanoparticle properties by engineering their size, shape and surface chemistry to enhance the sensitivity and specificity of the lateral flow tests.

Thesis advisor: Prof. Lee Gehrke

Thesis committee:

Dr. Kim Hamad-Schifferli

Prof. Rohit Karnik

Prof. Kim Vandiver