Characterization of the capsule phenotype in all1∆ Cryptococcus neoformans
Alex Goodell1,2,3, Neena Jain1, Mythri Subramaniam1, Bettina Fries1
1 Department of Medicine & Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA;  2 SURP, Sue Golding Graduate Division of Biomedical Sciences, Albert Einstein College of  Medicine, Bronx, NY, USA; 3 Department of Biology, University of Oregon, Eugene, OR, USA

Cryptococcus neoformans is an encapsulated fungal pathogen that infects mostly immunocompromised patients presenting chronic meningoencephalitis, causing upwards of 600,000 deaths annually. The organism has a unique polysaccharide (PS) capsule which varies in size according to environmental conditions such as carbon dioxide levels, iron starvation and pH. Increased capsule size has been linked to virulence in mammalian hosts. By shedding the capsule, excess PS causes agitation of the meninges and is associated with high inter-cranial pressure (ICP). Increased capsule size has also been shown to cause decreased susceptibility to both anti-fungal medication and phagocytosis by immune cells. The capsule character of C. neoformans var. neoformans has been shown to microevolve, undergoing a “phenotypic switch,” from a smooth (SM) to a mucoid (MC) appearance invivo. MC switch variants are more virulent and were shown to down-regulate one gene in particular, allergen 1 (all1), of which homologs have been found in other strains, such as C. neoformans var. grubii. This project analyzes the character of the PS capsule in wildtype, all1 knockout mutant, and reconstituted strains in RC-2 and H99 strains in a variety of medium. Characterization is done through photography and cryptocrit analysis. Results show increased capsule size when incubation conditions have low iron, high thiamine, or minimal media. All1 mutants consistently show smaller capsule size. This suggests that the all1 protein plays a role in capsule formation during inducing conditions. Future experiments on the all1 protein interactions may yield interesting results.