title: The elicitin-like glycoprotein, ELI025, is secreted by the pathogenic oomycete Pythium insidiosum and evades host antibody responses.
abstract: Pythium insidiosum is a unique oomycete that can infect humans and animals. Patients with a P. insidiosum infection (pythiosis) have high rates of morbidity and mortality. The pathogen resists conventional antifungal drugs. Information on the biology and pathogenesis of P. insidiosum is limited. Many pathogens secrete proteins, known as effectors, which can affect the host response and promote the infection process. Elicitins are secretory proteins and are found only in the oomycetes, primarily in Phytophthora and Pythium species. In plant-pathogenic oomycetes, elicitins function as pathogen-associated molecular pattern molecules, sterol carriers, and plant defense stimulators. Recently, we reported a number of elicitin-encoding genes from the P. insidiosum transcriptome. The function of elicitins during human infections is unknown. One of the P. insidiosum elicitin-encoding genes, ELI025, is highly expressed and up-regulated at body temperature. This study aims to characterize the biochemical, immunological, and genetic properties of the elicitin protein, ELI025. A 12.4-kDa recombinant ELI025 protein (rELI025) was expressed in Escherichia coli. Rabbit anti-rELI025 antibodies reacted strongly with the native ELI025 in P. insidiosum's culture medium. The detected ELI025 had two isoforms: glycosylated and non-glycosylated. ELI025 was not immunoreactive with sera from pythiosis patients. The region near the transcriptional start site of ELI025 contained conserved oomycete core promoter elements. In conclusion, ELI025 is a small, abundant, secreted glycoprotein that evades host antibody responses. ELI025 is a promising candidate for development of diagnostic and therapeutic targets for pythiosis.
authors: 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: Tassanee
authors: T
authors: Lerksuthirat
authors: Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors: Tassanee
authors: T
authors: Lohnoo
authors: Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors: Ruchuros
authors: R
authors: Inkomlue
authors: Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand; Molecular Medicine Program, Multidisciplinary Unit, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors: Thidarat
authors: T
authors: Rujirawat
authors: Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors: Wanta
authors: W
authors: Yingyong
authors: Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors: Rommanee
authors: R
authors: Khositnithikul
authors: Proteomics Research Laboratory, Genome Institute, National Science and Technology Development Agency, Pathum Thani, Thailand.
authors: Narumon
authors: N
authors: Phaonakrop
authors: Proteomics Research Laboratory, Genome Institute, National Science and Technology Development Agency, Pathum Thani, Thailand.
authors: Sittiruk
authors: S
authors: Roytrakul
authors: Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, United States of America.
authors: Thomas D
authors: TD
authors: Sullivan
authors: Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors: Theerapong
authors: T
authors: Krajaejun
mesh_terms: D000595:Amino Acid Sequence; D000917:Antibody Formation / Q000276:immunology*; D001483:Base Sequence; D003001:Cloning, Molecular; D016678:Genome; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D006031:Glycosylation; D054884:Host-Pathogen Interactions / Q000276:immunology*; D006801:Humans; D057131:Immune Evasion; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010802:Phylogeny; D011401:Promoter Regions, Genetic / Q000235:genetics; D020543:Proteome / Q000378:metabolism; D011775:Pythium / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D059467:Transcriptome / Q000235:genetics
chemical_list: D006023:Glycoproteins; D020543:Proteome; D011994:Recombinant Proteins