Virus-like particle analysis in yeast homogenate using a laser light-scattering assay

Virus-like particles (VLPs) expressed intracellularly by the yeast S. cerev isiae have helped set the framework of a wide range of biologicals, particu larly as carriers for viral antigens. This article investigates the use of dynamic light scattering (DLS) for the rapid evaluation of the concentratio n and purity of VLPs to aid the complex purification strategy. Development of the assay was per formed in a high background process stream (yeast homo genate) and involved a change in the signal proportional to the VLP concent ration by addition of antibodies that bind on the VLP surface and detection of that size change by DLS. Overall, the assay was found to provide a sign ificant improvement of rapid monitoring alternatives for VLPs, exhibiting g ood sensitivity and speed of measurement. Data are given for the use of the DLS-based assay for optimization of VLP release during a yeast cell disrup tion treatment. (C) 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 63: 290- 297, 1999.