Session Speaker

A quantum dot-based antiviral assay with potential utilization in the high throughput screening of novel antiretroviral compounds
Zafar Khan

Quantum dots (QDots) are fluorescent semiconductor nanocrystals with a narrow emission spectrum, high quantum yield, and excellent photostability. Furthermore, QDots can be conjugated with biological molecules while retaining their optical properties. These unique properties of QDots have been utilized to develop a fluorescent binding assay using biotinylated HTLV-1 conjugated with streptavidin-coated QDots that enabled both qualitative and quantitative analyses of viral binding. The specificity and linearity of the assay was demonstrated utilizing T cells, the primary HTLV-1-susceptible cell population. Furthermore, Differential binding of HTLV-1 was analyzed in various cell types of clinical relevance including primary CD4⁺ and CD8⁺ T cells, dendritic cells (DCs), monocytes, bone marrow progenitor cells, and epithelial cells. DCs exhibited maximum binding affinity when compared to other primary cells. Finally, the high throughput use of the assay was demonstrated by using an array of blocking antibodies against a putative HTLV-1 receptor on DCs; DC-SIGN (dendritic cell-specific ICAM-3-grabbing non-integrin). The assay is currently being utilized in an automated robotic system to screen a large library of small molecule inhibitors (average molecular weight 350 Dalton) against retroviral envelope protein (HTLV-1 gp46 and HIV-1 gp120) binding to cell surface receptors. Overall, these results demonstrated that this novel high throughput assay can be utilized to study the binding of any biotinylated virus and has implications for identification of viral binding inhibitors as well as host membrane proteins that may serve as receptors for viral entry.