title: Geographic variation in the elicitin-like glycoprotein, ELI025, of Pythium insidiosum isolated from human and animal subjects.
abstract: Oomycetes are fungus-like in appearance, but form a distinct clade within the eukaryotes. While most pathogenic oomycetes infect plants, the understudied oomycete Pythium insidiosum infects humans and animals, and causes a life-threatening infectious disease, called pythiosis. Phylogenetic analyses divide P. insidiosum into 3 groups, according to geographic origins: Clade-I (Americas), Clade-II (Asia and Australia), and Clade-III (Thailand). Surgical removal of the infected organ is the inevitable treatment for patients with pythiosis, but it is often too late or unsuccessful, and many patients die from advanced infection. Understanding P. insidiosum's basic biology could lead to improved infection control. Elicitins, a unique group of proteins found only in oomycetes, are involved in sterol acquisition and stimulation of host responses. Recently, we identified glycosylated and non-glycosylated forms of the elicitin-like protein, ELI025, which is secreted by P. insidiosum, and detected during P. insidiosum infection. In this study, we investigated geographic variation of ELI025 in 24 P. insidiosum strains isolated from humans, animals, and the environment. Genotypes of ELI025, based on 2 sets of PCR primers, correlated well with rDNA-based phylogenetic grouping. Unlike strains in Clade-I and -II, Clade-III strains secreted no glycosylated ELI025. Sera from 17 pythiosis patients yielded a broad range of antibody responses against ELI025, and ∼30% lacked reactivity against the protein. Selective production or secretion of glycosylated ELI025 by different P. insidiosum strains might contribute to the variable host antibody responses. In conclusion, ELI025 was secreted by all P. insidiosum strains isolated from different hosts and geographic origins, but the protein had different biochemical, and immunological characteristics. These finding contribute to the better understanding of the biology and evolution of P. insidiosum, and could lead to appropriate clinical application of the ELI025 protein for diagnosis or treatment of pythiosis.
authors.affiliation: Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand; Molecular Medicine Program, Multidisciplinary Unit, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Tassanee
authors.initials: T
authors.lastname: Lerksuthirat
authors.affiliation: Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Tassanee
authors.initials: T
authors.lastname: Lohnoo
authors.affiliation: Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand; Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand; Molecular Medicine Program, Multidisciplinary Unit, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Thidarat
authors.initials: T
authors.lastname: Rujirawat
authors.affiliation: Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Wanta
authors.initials: W
authors.lastname: Yingyong
authors.affiliation: Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Nujarin
authors.initials: N
authors.lastname: Jongruja
authors.affiliation: Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand. Electronic address: mr_en@hotmail.com.
authors.forename: Theerapong
authors.initials: T
authors.lastname: Krajaejun
mesh_terms: D000818:Animals; D004275:DNA, Ribosomal / Q000032:analysis; D006023:Glycoproteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D010802:Phylogeny; D058974:Phylogeography; D058968:Pythiosis / Q000276:immunology / Q000378:metabolism / Q000469:parasitology*; D011775:Pythium / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D017422:Sequence Analysis, DNA
chemical_list: D004275:DNA, Ribosomal; D006023:Glycoproteins
keywords: ELI025; Elicitin; Geographic variation; Pythiosis; Pythium insidiosum