title: Characterization of the antigenicity of Cpl1, a surface protein of Cryptococcus neoformans var. neoformans.
abstract: Cryptococcus neoformans var. neoformans is an important fungal pathogen. The capsule is a well established virulence factor and a target site for diagnostic tests. The CPL1 gene is required for capsular formation and virulence. The protein product Cpl1 has been proposed to be a secreted protein, but the characteristics of this protein have not been reported. Here we sought to characterize Cpl1. Phylogenetic analysis showed that the Cpl1 of C. neoformans var. neoformans and the Cpl1 orthologs identified in C. neoformans var. grubii and C. gattii formed a distinct cluster among related fungi; while the putative ortholog found in Trichosporon asahii was distantly related to the Cryptococcus cluster. We expressed Cpl1 abundantly as a secreted His-tagged protein in Pichia pastoris. The protein was used to immunize guinea pigs and rabbits for high titer mono-specific polyclonal antibody that was shown to be highly specific against the cell wall of C. neoformans var. neoformans and did not cross react with C. gattii, T. asahii, Aspergillus spp., Candida spp. and Penicillium spp. Using the anti-Cpl1 antibody, we detected Cpl1 protein in the fresh culture supernatant of C. neoformans var. neoformans and we showed by immunostaining that the Cpl1 protein was located on the surface. The Cpl1 protein is a specific surface protein of C. neoformans var. neoformans.
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, University of Hong Kong, Hong Kong Special Administrative Region.
authors.forename: Jian-Piao
authors.initials: JP
authors.lastname: Cai
authors.affiliation: Center for Clinical Laboratory, Zhujiang Hospital, Southern Medical University, Guangzhou, People's Republic of ChinaDepartment of Clinical Laboratory, Hainan Provincial People's Hospital, Haikou, People's Republic of China.
authors.forename: Ling-Li
authors.initials: LL
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, Carol Yu Centre for Infection, Research Centre of Infection and Immunology, Department of Microbiology, University of Hong Kong, Hong Kong Special Administrative Region.
authors.forename: Kelvin K W
authors.initials: KK
authors.lastname: To
authors.affiliation: Department of Microbiology, University of Hong Kong, Hong Kong Special Administrative Region.
authors.forename: Candy C Y
authors.initials: CC
authors.lastname: Lau
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, Carol Yu Centre for Infection, Research Centre of Infection and Immunology, Department of Microbiology, University of Hong Kong, Hong Kong Special Administrative Region.
authors.forename: Patrick C Y
authors.initials: PC
authors.lastname: Woo
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, Carol Yu Centre for Infection, Research Centre of Infection and Immunology, Department of Microbiology, University of Hong Kong, Hong Kong Special Administrative Region.
authors.forename: Susanna K P
authors.initials: SK
authors.lastname: Lau
authors.affiliation: Center for Clinical Laboratory, Zhujiang Hospital, Southern Medical University, Guangzhou, People's Republic of China.
authors.forename: Yong-Hui
authors.initials: YH
authors.lastname: Guo
authors.affiliation: Department of Microbiology, University of Hong Kong, Hong Kong Special Administrative Region.
authors.forename: Antonio H Y
authors.initials: AH
authors.lastname: Ngan
authors.affiliation: Center for Clinical Laboratory, Zhujiang Hospital, Southern Medical University, Guangzhou, People's Republic of China.
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Che
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, Carol Yu Centre for Infection, Research Centre of Infection and Immunology, Department of Microbiology, University of Hong Kong, Hong Kong Special Administrative Region kyyuen@hku.hk.
authors.forename: Kwok-Yung
authors.initials: KY
authors.lastname: Yuen
mesh_terms: D000818:Animals; D000908:Antibodies, Fungal / Q000032:analysis / Q000276:immunology; D002473:Cell Wall / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D003455:Cryptococcus neoformans / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D006168:Guinea Pigs; D007114:Immunization; D010802:Phylogeny; D021381:Protein Transport; D011817:Rabbits
chemical_list: D000908:Antibodies, Fungal; D005656:Fungal Proteins
keywords: CLP1; Cryptococcus; capsule; fungus; immunostaining