Fluorescence detection of cationic amyloid fibrils in human semen.

Cationic amyloid fibrils, including the Semen Enhancer of Virus Infection (SEVI), have recently been described in human semen. Simple methods for quantitating these fibrils are needed to improve our understanding of their biological function. We performed high-throughput screening to identify molecules that bind SEVI, and identified a small molecule (8E2), that fluoresced brightly in the presence of SEVI and other cationic fibrils. 8E2 bound SEVI with almost 40-fold greater affinity than thioflavin-T, and could efficiently detect high molecular weight fibrils in human seminal fluid.