DRVision Technologies 1 article published in JoVE Immunology and Infection Size Matters: Measurement of Capsule Diameter in Cryptococcus neoformans Tiffany Guess1, Hoyin Lai2, Serenah E. Smith1, Linda Sircy1, Kirsten Cunningham1, David E. Nelson*1, Erin E. McClelland*1 1Department of Biology, Middle Tennessee State University, 2DRVision Technologies The polysaccharide capsule is the primary virulence factor in Cryptococcus neoformans, and its size correlates with strain virulence. Capsule diameter measurements are used in phenotypic testing and to gauge therapeutic efficacy. Here a standard method of capsule induction is presented, and two methods of staining and measuring diameter are compared.