Research activity information

• Skeleton binding protein 1 localizes to the Maurer's cleft and interacts with PfHSP70-1 and PfHSP70-x in Plasmodium falciparum gametocyte-infected erythrocytes

  Ayaka Omoda, Konomi Matsumoto, Ken-ichi Yoshino, Mayumi Tachibana, Takafumi Tsuboi, Motomi Torii, Tomoko Ishino, Hideyuki Iriko

  Elsevier BV, Jun. 2024, Parasitology International, 100, 102864 - 102864, English

  [Refereed]

  Scientific journal


• Identification of a novel protein localized to the crystalloid of the plasmodium ookinete.

  Mayumi Tachibana, Minami Baba, Hideyuki Iriko, Naoaki Shinzawa, Motomi Torii, Tomoko Ishino

  Reducing Plasmodium parasite transmission via the mosquito vector is a promising strategy for malaria control and elimination in endemic regions. In the mosquito midgut after the ingestion of an infected blood meal, malaria parasite gametes egress from erythrocytes and fertilize to develop into motile ookinetes that traverse midgut epithelial cells and transform into oocysts adjacent the basal lamina. Plasmodium ookinetes and young oocysts possess a unique organelle called the crystalloid; which has a honeycomb-like matrix structure and is indicated to be involved in sporozoite formation and maturation. In this study, we identified a novel crystalloid protein, PY17X_1113800, that is exclusively expressed in developing ookinetes. The protein possesses a signal peptide sequence, but lacks a transmembrane domain or GPI anchor signal sequence, as well as predicted adhesive domains which are characterisitic of many crystalloid proteins. The protein is highly conserved across the phylum Apicomplexa and within the greater clade Alveolata, such as Vitrella and the ciliates Paramecium and Tetrahymena, but is absent in cryptosporidia.

  Mar. 2024, Parasitology international, 102892 - 102892, English, International magazine

  [Refereed]

  Scientific journal


• Roles of the RON3 C-terminal fragment in erythrocyte invasion and blood-stage parasite proliferation in Plasmodium falciparum

  Daisuke Ito, Yoko Kondo, Eizo Takashima, Hideyuki Iriko, Amporn Thongkukiatkul, Motomi Torii, Hitoshi Otsuki

  Plasmodium species cause malaria, and in the instance of Plasmodium falciparum is responsible for a societal burden of over 600,000 deaths annually. The symptoms and pathology of malaria are due to intraerythocytic parasites. Erythrocyte invasion is mediated by the parasite merozoite stage, and is accompanied by the formation of a parasitophorous vacuolar membrane (PVM), within which the parasite develops. The merozoite apical rhoptry organelle contains various proteins that contribute to erythrocyte attachment and invasion. RON3, a rhoptry bulb membrane protein, undergoes protein processing and is discharged into the PVM during invasion. RON3-deficient parasites fail to develop beyond the intraerythrocytic ring stage, and protein export into erythrocytes by the Plasmodium translocon of exported proteins (PTEX) apparatus is abrogated, as well as glucose uptake into parasites. It is known that truncated N- and C-terminal RON3 fragments are present in rhoptries, but it is unclear which RON3 fragments contribute to protein export by PTEX and glucose uptake through the PVM. To investigate and distinguish the roles of the RON3 C-terminal fragment at distinct developmental stages, we used a C-terminus tag for conditional and post-translational control. We demonstrated that RON3 is essential for blood-stage parasite survival, and knockdown of RON3 C-terminal fragment expression from the early schizont stage induces a defect in erythrocyte invasion and the subsequent development of ring stage parasites. Protein processing of full-length RON3 was partially inhibited in the schizont stage, and the RON3 C-terminal fragment was abolished in subsequent ring-stage parasites compared to the RON3 N-terminal fragment. Protein export and glucose uptake were abrogated specifically in the late ring stage. Plasmodial surface anion channel (PSAC) activity was partially retained, facilitating small molecule traffic across the erythrocyte membrane. The knockdown of the RON3 C-terminal fragment after erythrocyte invasion did not alter parasite growth. These data suggest that the RON3 C-terminal fragment participates in erythrocyte invasion and serves an essential role in the progression of ring-stage parasite growth by the establishment of the nutrient-permeable channel in the PVM, accompanying the transport of ring-stage parasite protein from the plasma membrane to the PVM.

  Frontiers Media SA, Jun. 2023, Frontiers in Cellular and Infection Microbiology, 13

  [Refereed]

  Scientific journal


• Cysteine Residues in Region 6 of the Plasmodium yoelii Erythrocyte-Binding-like Ligand That Are Related to Its Localization and the Course of Infection

  Hitoshi OtsukiOsamu KanekoDaisuke ItoYoko KondoHideyuki IrikoTomoko IshinoMayumi TachibanaTakafumi, TsuboiMotomi Torii

  Plasmodium malaria parasites use erythrocyte-binding-like (EBL) ligands to invade erythrocytes in their vertebrate host. EBLs are released from micronemes, which are secretory organelles located at the merozoite apical end and bind to erythrocyte surface receptors. Because of their essential nature, EBLs have been studied as vaccine candidates, such as the Plasmodium vivax Duffy binding protein. Previously, we showed through using the rodent malaria parasite Plasmodium yoelii that a single amino acid substitution within the EBL C-terminal Cys-rich domain (region 6) caused mislocalization of this molecule and resulted in alteration of the infection course and virulence between the non-lethal 17X and lethal 17XL strains. In the present study, we generated a panel of transgenic P. yoelii lines in which seven of the eight conserved Cys residues in EBL region 6 were independently substituted to Ala residues to observe the consequence of these substitutions with respect to EBL localization, the infection course, and virulence. Five out of seven transgenic lines showed EBL mislocalizations and higher parasitemias. Among them, three showed increased virulence, whereas the other two did not kill the infected mice. The remaining two transgenic lines showed low parasitemias similar to their parental 17X strain, and their EBL localizations did not change. The results indicate the importance of Cys residues in EBL region 6 for EBL localization, parasite infection course, and virulence and suggest an association between EBL localization and the parasite infection course.

  MDPI, Mar. 2023, Biomolecules, 13(3) (3), 458, English, International magazine

  [Refereed]

  Scientific journal


• PSOP1, putative secreted ookinete protein 1, is localized to the micronemes of Plasmodium yoelii and P. berghei ookinetes.

  Mayumi Tachibana, Hideyuki Iriko, Minami Baba, Motomi Torii, Tomoko Ishino

  Plasmodium parasites cause malaria in mammalian hosts and are transmitted by Anopheles mosquitoes. Activated gametocytes in the mosquito midgut egress from erythrocytes followed by fertilization and zygote formation. Zygotes differentiate into motile invasive ookinetes, which penetrate the midgut epithelium before forming oocysts beneath the basal lamina. Ookinete development and traversal across the mosquito midgut wall are major bottlenecks in the parasite life cycle. In ookinetes, surface proteins and proteins stored in apical organelles have been shown to be involved in parasite-host interactions. A group of ookinete proteins that are predicted to have such functions are named PSOPs (putative secreted ookinete protein). PSOP1 is possibly involved in migration through the midgut wall, and here its subcellular localization was examined in ookinetes by immunoelectron microscopy. PSOP1 localizes to the micronemes of Plasmodium yoelii and Plasmodium berghei ookinetes, indicating that it is stored and possibly apically secreted during ookinete penetration through the mosquito midgut wall.

  Oct. 2021, Parasitology international, 84, 102407 - 102407, English, International magazine

  [Refereed]

  Scientific journal


• Skeleton binding protein 1 (SBP1) of Plasmodium falciparum accumulates in electron-dense material before passing through the parasitophorous vacuole membrane

  Hideyuki Iriko, Tomoko Ishino, Mayumi Tachibana, Ayaka Omoda, Motomi Torii, Takafumi Tsuboi

  Elsevier BV, Apr. 2020, Parasitology International, 75, 102003 - 102003

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Observation of morphological changes of female osmiophilic bodies prior to Plasmodium gametocyte egress from erythrocytes.

  Tomoko Ishino, Mayumi Tachibana, Minami Baba, Hideyuki Iriko, Takafumi Tsuboi, Motomi Torii

  Plasmodium parasites cause malaria in mammalian hosts and are transmitted by Anopheles mosquitoes. Gametocytes, which differentiate from asexual-stage parasites, are activated by environmental changes when ingested into the mosquito midgut, and are rapidly released from erythrocytes prior to fertilization. Secretory proteins localized to osmiophilic bodies (OBs), organelles unique to gametocytes, have been reported to be involved in female gametocyte egress. In this study, we investigate the dynamics of OBs in activated gametocytes of Plasmodium falciparum and Plasmodium yoelii using the female OB-specific marker protein, G377. After activation, female gametocyte OBs migrate to the parasite surface and fuse to form large vesicles beneath the parasite plasma membrane. At the marginal region of female gametocytes, fused vesicles secrete contents by exocytosis into the parasitophorous vacuole space, prior to parasite egress via the break-down of the erythrocyte membrane. This is the first detailed description of how proteins are transported through osmiophilic bodies.

  Mar. 2020, Molecular and biochemical parasitology, 236, 111261 - 111261, English, International magazine

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Dibothriocephalus nihonkaiensis infection identified by pathological and genetic analyses -a case report and a recent literature review of human diphyllobothriasis

  Yoshitane Tsukamoto, Hideyuki Iriko, Shohei Matsuo, Yoshihiro Shimono, Junichi Miyazaki, Hironori Tanaka, Toshiya Komatsu, Seiji Azuma, Hiroko Oota, Yui Yamashita, Mizuka Ohkouchi, Yuka Hashikura, Seiichi Hirota

  Elsevier BV, Jun. 2019, Human Pathology: Case Reports, 16, 200298 - 200298

  [Refereed]

  Scientific journal


• Antibodies against a Plasmodium falciparum RON12 inhibit merozoite invasion into erythrocytes.

  Daisuke Ito, Eizo Takashima, Tsutomu Yamasaki, Shinya Hatano, Tomoyuki Hasegawa, Kazutoyo Miura, Masayuki Morita, Amporn Thongkukiatkul, Mahamadou Diakite, Carole A Long, Jetsumon Sattabongkot, Rachanee Udomsangpetch, Hideyuki Iriko, Tomoko Ishino, Takafumi Tsuboi

  Proteins coating Plasmodium merozoite surface and secreted from its apical organelles are considered as promising vaccine candidates for blood-stage malaria. The rhoptry neck protein 12 of Plasmodium falciparum (PfRON12) was recently reported as a protein specifically expressed in schizonts and localized to the rhoptry neck of merozoites. Here, we assessed its potential as a vaccine candidate. We expressed a recombinant PfRON12 protein by a wheat germ cell-free system to obtain anti-PfRON12 antibody. Immunoblot analysis of schizont lysates detected a single band at approximately 40 kDa under reducing conditions, consistent with the predicted molecular weight. Additionally, anti-PfRON12 antibody recognized a single band around 80 kDa under non-reducing conditions, suggesting native PfRON12 forms a disulfide-bond-mediated multimer. Immunofluorescence assay and immunoelectron microscopy revealed that PfRON12 localized to the rhoptry neck of merozoites in schizonts and to the surface of free merozoites. The biological activity of anti-PfRON12 antibody was tested by in vitro growth inhibition assay (GIA), and the rabbit antibodies significantly inhibited merozoite invasion of erythrocytes. We then investigated whether PfRON12 is immunogenic in P. falciparum-infected individuals. The sera from P. falciparum infected individuals in Thailand and Mali reacted with the recombinant PfRON12. Furthermore, human anti-PfRON12 antibodies affinity-purified from Malian serum samples inhibited merozoite invasion of erythrocytes in vitro. Moreover, pfron12 is highly conserved with only 4 non-synonymous mutations in the coding sequence from approximately 200 isolates deposited in PlasmoDB. These results suggest that PfRON12 might be a potential blood-stage vaccine candidate antigen against P. falciparum.

  Feb. 2019, Parasitology international, 68(1) (1), 87 - 91, English, International magazine

  [Refereed]

  Scientific journal


• Plasmodium RON12 localizes to the rhoptry body in sporozoites.

  Yuki Oda-Yokouchi, Mayumi Tachibana, Hideyuki Iriko, Motomi Torii, Tomoko Ishino, Takafumi Tsuboi

  Invasion of host cells by apicomplexan parasites is mediated by proteins released from microneme, rhoptry, and dense granule secretory organelles located at the apical end of parasite invasive forms. Microneme secreted proteins establish interactions with host cell receptors and induce exocytosis of the rhoptry organelle. Rhoptry proteins are involved in target cell invasion as well as the formation of the parasitophorous vacuole in which parasites reside during development within the host cell. In Plasmodium merozoites, the rhoptry neck protein (RON) complex consists of RON2, RON4, and RON5, and interacts with apical membrane antigen 1 (AMA1) as a critical structure of the invasion moving junction. PfRON12 is known to localize to the rhoptry neck of merozoites, but its function remains obscure. The roles of RON proteins are largely unknown in sporozoites, the second invasive form of Plasmodium which possesses a conserved apical end secretory structure. Here, we confirm that RON12 is expressed in the rhoptry neck of merozoites in rodent malaria parasites, whereas in contrast we show that RON12 is localized to the rhoptry body in sporozoites. Phenotypic analysis of Plasmodium berghei ron12-disrupted mutants revealed that RON12 is dispensable for sporogony, invasion of mosquito salivary glands and mouse hepatocytes, and development in hepatocytes.

  Feb. 2019, Parasitology international, 68(1) (1), 17 - 23, English, International magazine

  [Refereed]

  Scientific journal


• Plasmodium falciparum Exported Protein 1 is localized to dense granules in merozoites.

  Iriko H, Ishino T, Otsuki H, Ito D, Tachibana M, Torii M, Tsuboi T

  Jun. 2018, Parasitol Int., 67(5) (5), 637 - 639, English

  [Refereed]

  Scientific journal


• Erratum: Hasan, I., et al. A Galactose-Binding Lectin Isolated from Aplysia kurodai (Sea Hare) Eggs Inhibits Streptolysin-Induced Hemolysis. Molecules 2014, 19, 13990-14003

  Imtiaj Hasan, Miharu Watanabe, Naoto Ishizaki, Yoshiko Sugita-Konishi, Yasushi Kawakami, Jun Suzuki, Chikaku Dogasaki, Sultana Rajia, Sarkar M.A. Kawsar, Yasuhiro Koide, Robert A. Kanaly, Shigeki Sugawara, Masahiro Hosono, Yukiko Ogawa, Yuki Fujii, Hideyuki Iriko, Jiharu Hamako, Taei Matsui, Yasuhiro Ozeki

  MDPI AG, Jan. 2016, Molecules, 21(1) (1), English

  [Refereed]

  Scientific journal


• Discovery of Novel Plasmodium falciparum Pre-Erythrocytic Antigens for Vaccine Development

  Joao C. Aguiar, Jessica Bolton, Joyce Wanga, John B. Sacci, Hideyuki Iriko, Julie K. Mazeika, Eun-Taek Han, Keith Limbach, Noelle B. Patterson, Martha Sedegah, Ann-Marie Cruz, Takafumi Tsuboi, Stephen L. Hoffman, Daniel Carucci, Michael R. Hollingdale, Eileen D. Villasante, Thomas L. Richie

  Aug. 2015, PLOS ONE, 10(8) (8), English

  [Refereed]

  Scientific journal


• Plasmodium vivax gametocyte proteins, Pvs48/45 and Pvs47, induce transmission-reducing antibodies by DNA immunization

  Mayumi Tachibana, Nantavadee Suwanabun, Osamu Kaneko, Hideyuki Iriko, Hitoshi Otsuki, Jetsumon Sattabongkot, Akira Kaneko, Socrates Herrera, Motomi Torii, Takafumi Tsuboi

  Apr. 2015, VACCINE, 33(16) (16), 1901 - 1908, English

  [Refereed]

  Scientific journal


• A Galactose-Binding Lectin Isolated from Aplysia kurodai (Sea Hare) Eggs Inhibits Streptolysin-Induced Hemolysis

  Imtiaj Hasan, Miharu Watanabe, Naoto Ishizaki, Yoshiko Sugita-Konishi, Yasushi Kawakami, Jun Suzuki, Chikaku Dogasaki, Sultana Rajia, Sarkar M. A. Kawsar, Yasuhiro Koide, Robert A. Kanaly, Shigeki Sugawara, Masahiro Hosono, Yukiko Ogawa, Yuki Fujii, Hideyuki Iriko, Jiharu Hamako, Taei Matsui, Yasuhiro Ozeki

  Sep. 2014, MOLECULES, 19(9) (9), 13990 - 14003, English

  [Refereed]

  Scientific journal


• Natural Infection of Plasmodium falciparum Induces Inhibitory Antibodies against Gametocyte Development in Human Hosts

  Natda Tonwong, Jetsumon Sattabongkot, Takafumi Tsuboi, Hideyuki Iriko, Satoru Takeo, Jeeraphat Sirichaisinthop, Rachanee Udomsangpetch

  Mar. 2012, JAPANESE JOURNAL OF INFECTIOUS DISEASES, 65(2) (2), 152 - 156, English

  [Refereed]

  Scientific journal


• N-Terminal Prodomain of Pfs230 Synthesized Using a Cell-Free System Is Sufficient To Induce Complement-Dependent Malaria Transmission-Blocking Activity

  Mayumi Tachibana, Yimin Wu, Hideyuki Iriko, Olga Muratova, Nicholas J. MacDonald, Jetsumon Sattabongkot, Satoru Takeo, Hitoshi Otsuki, Motomi Torii, Takafumi Tsuboi

  Aug. 2011, CLINICAL AND VACCINE IMMUNOLOGY, 18(8) (8), 1343 - 1350, English

  [Refereed]

  Scientific journal


• Helminth Infections Prevent Autoimmune Diseases through Th2-Type Immune Response

  Soji Fukumoto, Hideyuki Iriko, Hitoshi Otsuki

  Sep. 2009, YONAGO ACTA MEDICA, 52(3) (3), 95 - 104, English

  [Refereed]

  Scientific journal


• A small-scale systematic analysis of alternative splicing in Plasmodium falciparum

  Hideyuki Iriko, Ling Jin, Osamu Kaneko, Satoru Takeo, Eun-Taek Han, Mayumi Tachibana, Hitoshi Otsuki, Motomi Torii, Takafumi Tsuboi

  Jun. 2009, PARASITOLOGY INTERNATIONAL, 58(2) (2), 196 - 199, English

  [Refereed]

  Scientific journal


• Single amino acid substitution in Plasmodium yoelii erythrocyte ligand determines its localization and controls parasite virulence.

  Otsuki H, Kaneko O, Thongkukiatkul A, Tachibana M, IRIKO HIDEYUKI, Takeo S, Tsuboi T, Torii M

  The major virulence determinant of the rodent malaria parasite, Plasmodium yoelii, has remained unresolved since the discovery of the lethal line in the 1970s. Because virulence in this parasite correlates with the ability to invade different types of erythrocytes, we evaluated the potential role of the parasite erythrocyte binding ligand, PyEBL. We found 1 amino acid substitution in a domain responsible for intracellular trafficking between the lethal and nonlethal parasite lines and, furthermore, that the intracellular localization of PyEBL was distinct between these lines. Genetic modification showed that this substitution was responsible not only for PyEBL localization but also the erythrocyte-type invasion preference of the parasite and subsequently its virulence in mice. This previously unrecognized mechanism for altering an invasion phenotype indicates that subtle alterations of a malaria parasite ligand can dramatically affect host–pathogen interactions and malaria virulence.

  the National Academy of Sciences, 2009, Proc Natl Acad Sci U S A, 106(17) (17), 7167 - 7172, English

  [Refereed]

  Scientific journal


• Wheat germ cell-free system-based production of malaria proteins for discovery of novel vaccine candidates

  Takafumi Tsuboi, Satoru Takeo, Hideyuki Iriko, Ling Jin, Masateru Tsuchimochi, Shusaku Matsuda, Eun-Taek Han, Hitoshi Otsuki, Osamu Kaneko, Jetsumon Sattabongkot, Rachanee Udomsangpetch, Tatsuya Sawasaki, Motomi Torii, Yaeta Endo

  Apr. 2008, INFECTION AND IMMUNITY, 76(4) (4), 1702 - 1708, English

  [Refereed]

  Scientific journal


• Diversity and evolution of the rhoph1/clag multigene family of Plasmodium falciparum

  Hideyuki Iriko, Osamu Kaneko, Hitoshi Otsuki, Takafumi Tsuboi, Xin-zhuan Su, Kazuyuki Tanabe, Motomi Torii

  Mar. 2008, MOLECULAR AND BIOCHEMICAL PARASITOLOGY, 158(1) (1), 11 - 21, English

  [Refereed]

  Scientific journal


• Expression of malaria vaccine candidates using a wheat germ cell-free protein synthesis system without codon optimisation.

  Takafumi Tsuboi, Satoru Takeo, Hideyuki Iriko, Ling Jin, Masateru Tsuchimochi, Shusaku Matsuda, Eun-Taek Han, Hitoshi Otsuki, Osamu Kaneko, Jetsumon Sattabongkot, Rachanee Udomsangpetch, Tatsuya Sawasaki, Motomi Torii, Yaeta Endo

  Jan. 2008, INTERNATIONAL JOURNAL FOR PARASITOLOGY, 38, S77 - S77, English

  [Refereed]


• Detection of four Plasmodium species by genus- and species-specific loop-mediated isothermal amplification for clinical diagnosis

  Eun-Taek Han, Risa Watanabe, Jetsumon Sattabongkot, Benjawan Khuntirat, Jeeraphat Sirichaisinthop, Hideyuki Iriko, Ling Jin, Satoru Takeo, Takafumi Tsuboi

  Aug. 2007, JOURNAL OF CLINICAL MICROBIOLOGY, 45(8) (8), 2521 - 2528, English

  [Refereed]

  Scientific journal


• コムギ胚芽無細胞タンパク質合成法：マラリアワクチン研究への応用

  坪井 敬文, 竹尾 暁, IRIKO HIDEYUKI, 金子 修, 鳥居 本美, 遠藤 弥重太

  2007, 愛媛医学, 26, 8 - 11, Japanese

  [Refereed]

  Research institution


• The Plasmodium vivax homolog of the ookinete adhesive micronemal protein, CTRP

  Osamu Kaneko, Thomas J. Templeton, Hideyuki Iriko, Mayumi Tachibana, Hitoshi Otsuki, Satoru Takeo, Jetsumon Sattabongkot, Motomi Torii, Takafumi Tsuboi

  Sep. 2006, PARASITOLOGY INTERNATIONAL, 55(3) (3), 227 - 231, English

  [Refereed]

  Scientific journal


• Screening of novel malaria transmission-blocking vaccine candidates using wheat germ cell-free protein synthesis system

  Hideyuki Iriko, Satoru Takeo, Ling Jin, Osamu Kaneko, Motomi Torii, Jetsumon Sattabongkot, Sanjay Singh, Tatsuya Sawasaki, Yaeta Endo, Takafumi Tsuboi

  Dec. 2005, AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE, 73(6) (6), 292 - 292, English

  [Refereed]


• Wheat germ cell-free system: A powerful tool to identify novel vaccine candidates based on the Plasmodium Falciparum genome database

  Takafumi Tsuboi, Satoru Takeo, Hideyuki Iriko, Ling Jin, Eun-Taek Han, Osamu Kaneko, Jetsumon Sattabongkot, Rachanee Udomsangpetch, Tatsuya Sawasaki, Motomi Torii, Yaeta Endo

  Dec. 2005, AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE, 73(6) (6), 338 - 338, English

  [Refereed]


• Apical expression of three RhopH1/Clag proteins as components of the Plasmodium falciparum RhopH complex

  O Kaneko, BYSY Lim, H Iriko, IT Ling, H Otsuki, M Grainger, T Tsuboi, JH Adams, D Mattei, AA Holder, M Torii

  Sep. 2005, MOLECULAR AND BIOCHEMICAL PARASITOLOGY, 143(1) (1), 20 - 28, English

  [Refereed]

  Scientific journal


• マラリア原虫の赤血球侵入に関わる多重遺伝子族

  金子 修, 大槻 均, IRIKO HIDEYUKI, 坪井 敬文, 鳥居 本美

  2003, 愛媛医学, 22, 102 - 109, Japanese

  [Refereed]

  Research institution


• Chemical structures and immunolocalization of glycosphingolipids isolated from Diphyllobothrium hottai adult worms and plerocercoids

  H Iriko, K Nakamura, H Kojima, N Iida-Tanaka, T Kasama, Y Kawakami, Ishizuka, I, A Uchida, Y Murata, Y Tamai

  Jul. 2002, EUROPEAN JOURNAL OF BIOCHEMISTRY, 269(14) (14), 3549 - 3559, English

  [Refereed]

  Scientific journal


• A monoclonal antibody against a glycolipid SEGLx from Spirometra erinaceieuropaei plerocercoid

  M Yanagisawa, H Kojima, Y Kawakami, H Iriko, T Nakamura, K Nakamura, A Uchida, Y Murata, Y Tamai

  Aug. 1999, MOLECULAR AND BIOCHEMICAL PARASITOLOGY, 102(2) (2), 225 - 235, English

  [Refereed]

  Scientific journal


• Glycosphingolipids in pseudophyllidean tapeworms

  Y Kawakami, H Iriko, M Yanagisawa, A Uchida, Y Murata, H Kojima, K Nakamura, Y Tamai

  1998, ICOPA IX - 9TH INTERNATIONAL CONGRESS OF PARASITOLOGY, 1145 - 1148, English

  [Refereed]

  International conference proceedings

• 原虫・寄生虫検査に強くなろう- II 吸虫類 肺寄生、肝・胆道寄生、消化管寄生、門脈寄生

  大槻 均, IRIKO HIDEYUKI, 蓼本 早百合, 福本 宗嗣

  2013, 臨床と微生物, 40(3) (3), 327 - 333, Japanese

  Introduction scientific journal


• 感染症症候群（第２版）-症候群から感染性単一疾患までを含めてー 上 病原体感染症編 VI. 原虫症, 吸虫症 <日本海裂頭条虫症, 広節裂頭条虫症>

  福本 宗嗣, 大槻 均, IRIKO HIDEYUKI, 蓼本 早百合

  2013, 別冊日本臨床 新領域別症候群シリーズ, 24, 733 - 737, Japanese

  Introduction scientific journal


• IMMUNIZATION WITH N-TERMINAL REGION OF A GAMETOCYTE PROTEIN PFS230 SUCCESSFULLY INDUCE TRANSMISSION-BLOCKING ANTIBODIES AGAINST PLASMODIUM FALCIPARUM

  Mayumi Tachibana, Hideyuki Iriko, Olga Muratova, Guanhong Song, Yimin Wu, Jetsumon Sattabongkot, Satoru Takeo, Hitoshi Otsuki, Motomi Torii, Takafumi Tsuboi

  Nov. 2009, AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE, 81(5) (5), 160 - 160, English

  Summary international conference


• 無細胞タンパク質合成系を用いた新規マラリア伝搬阻止ワクチン候補抗原の探索

  入子 英幸, 金 玲, 竹尾 暁, 大槻 均, 金子 修, 鳥居 本美, 坪井 敬文

  麻布大学, 31 Mar. 2009, 麻布大学雑誌 = Journal of Azabu University, 17, 66 - 66, Japanese


• IMMUNIZATION WITH RECOMBINANT PROTEINS OF A GAMETOCYTE PROTEIN PFS230 EXPRESSED USING WHEAT GERM CELL-FREE SYSTEM SUCCESSFULLY INDUCE TRANSMISSION-BLOCKING ANTIBODIES AGAINST PLASMODIUM FALCIPARUM

  Mayumi Tachibana, Hideyuki Iriko, Olga Muratova, Guanhong Song, Yimin Wu, Jetsumon Sattabongkot, Satoru Takeo, Hitoshi Otsuki, Motomi Torii, Takafumi Tsuboi

  Dec. 2008, AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE, 79(6) (6), 307 - 307, English

  Summary international conference


• Novel sporozoite antigen discovery of Plasmodium falciparum screened using human immunesera

  Ling Jin, Satoru Takeo, Hideyuki Iriko, Osamu Kaneko, Jetsumon Sattabongkot, Motomi Torii, Joao Carlos Aguiar, Takafumi Tsuboi

  Nov. 2007, AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE, 77(5) (5), 165 - 165, English

  Summary international conference


• Discovering novel malaria pre-erythrocytic antigens

  Joao Carlos Aguiar, Hideyuki Iriko, Fengying Huang, John B. Sacci, Laure Juompan, Ling Jin, Eun-Taek Han, Satoru Takeo, Urszula Krzych, Yaeta Endo, Thomas Richie, Takafumi Tsuboi

  Nov. 2006, AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE, 75(5) (5), 303 - 303, English

  Summary international conference


• Discovering novel blood stage malaria vaccine candidates: Screening with immune sera from falciparum malaria patients and asymptomatic parasite carriers

  Satoru Takeo, Ling Jin, Hirokazu Sakamoto, Eun-Taek Han, Hideyuki Iriko, Osamu Kaneko, Motomi Torii, Jetsumon Sattabongkot, Rachanee Udomsangpetch, Tatsuya Sawasaki, Yaeta Endo, Takafumi Tsuboi

  Nov. 2006, AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE, 75(5) (5), 302 - 302, English

  [Refereed]

  Summary international conference


• Recent situation of parasitic diseases and a note on diagnosis and treatment

  福本 宗嗣, 入子 英幸, 蓼本 早百合

  米子医学会, 2006, 米子医学雑誌, 57(6) (6), 201 - 215, Japanese


• 特徴的な糖鎖構造をもつ糖脂質 spirometosides のマンソン裂頭条虫 Spirometra erinacei における局在性

  入子 英幸, 柳沢 亮, 川上 泰, 内田 明彦, 村田 義彦, 中村 和生, 小嶋 久子, 玉井 洋一

  02 Jul. 1998, 脂質生化学研究, 40, 120 - 123, Japanese


• 鯨複殖門条虫のスフィンゴ糖脂質

  川上 泰, 柳澤 亮, 入子 英幸, 内田 明彦, 村田 義彦, 中村 和生, 小嶋 久子, 玉井 洋一

  13 Jun. 1997, 脂質生化学研究, 39, 123 - 126, Japanese

• Glycosphingolipids in prendophyllidean tapeworms (共著)

  9th International Congress of Parasitology, 1998

• 熱帯熱マラリア原虫の生殖母体期におけるGAP45 の分子局在解析と相互 作用分子の探索

  面田 彩馨, 伊坂 恵里奈, 松本 香乃実, 吉野 健一, 森田 将之, 橘 真由美, 高島 英造, 坪井 敬文, 鳥居 本美, 入子 英幸

  第94回 日本寄生虫学会大会, Mar. 2025, Japanese

  Oral presentation


• 熱帯熱マラリア原虫の未成熟生殖母体期のSBP1はPfHSP70と相互作用する

  面田彩馨, 松本香乃美, 吉野健一, 橘真由美, 石野智子, 伊藤大輔, 大槻 均, 坪井敬文, 鳥居本美, 入子英幸

  第93回日本寄生虫学会大会, Mar. 2024, Japanese


• 熱帯熱マラリア原虫の生殖母体期における原虫タンパク質輸送の解析

  面田彩馨, 岡田小夏, 伊坂恵里奈, 吉野健一, 橘真由美, 石野智子, 鳥居本美, 入子英幸

  第78 回日本寄生虫学会 西日本支部大会, Sep. 2023

  Oral presentation


• 感染赤血球試料からマラリア原虫由来タンパク質とヒト由来タンパク質を質量分析によって効率的かつ的確に同定する方法

  吉野健一, 面田彩馨, 岡田小夏, 竹内敦子, 入子英幸

  第71回質量分析総合討論会, May 2023

  Poster presentation


• 熱帯熱マラリア原虫生殖母体期の原虫タンパク質輸送におけるSBP1の機能解析

  面田 彩馨, 伊藤 大輔, 橘 真由美, 吉野 健一, 石野 智子, 大槻 均, 鳥居 本美, 入子 英幸

  第92回日本寄生虫学会大会（金沢市）, Mar. 2023

  Oral presentation


• 熱帯熱マラリア原虫の生殖母体期における寄生胞膜動態の解析

  伊坂恵里奈, 岡田小夏, 面田彩馨, 橘真由美, 石野智子, 鳥居本美, 入子英幸

  第77回 日本寄生虫学会西日本支部大会, Sep. 2022

  Oral presentation


• 熱帯熱マラリア原虫生殖母体期のSBP1と相互作用するタンパク質の検索

  面田彩馨, 岡田小夏, 伊坂恵里奈, 吉野健一, 橘真由美, 石野智子, 鳥居本美, 入子英幸

  第77 回日本寄生虫学会 西日本支部大会, Sep. 2022

  Oral presentation


• 熱帯熱マラリア原虫の生殖母体期におけるPTEX複合体の解析

  岡田小夏, 伊坂恵里奈, 面田彩馨, 吉野健一, 橘真由美, 石野智子, 鳥居本美, 入子英幸

  第77 回日本寄生虫学会 西日本支部大会, Sep. 2022

  Oral presentation


• 熱帯熱マラリア原虫生殖母体期のSBP1と相互作用するタンパク質の検索

  面田 彩馨, 岡田 小夏, 吉野 健一, 橘 真由美, 石野 智子, 鳥居 本美, 入子 英幸

  第55回 日本原生生物学会大会, Sep. 2022

  Oral presentation


• 熱帯熱マラリア原虫生殖母体期におけるPTEX複合体構成タンパク質の発現プロファイル解析

  岡田小夏, 伊坂 恵里奈, 面田 彩馨, 吉野 健一, 石野 智子, 橘真由美, 鳥居 本美, 高島 英造, 坪井 敬文, 入子 英幸

  第91回日本寄生虫学会大会, May 2022

  Poster presentation


• 熱帯熱マラリア原虫生殖母体期における SBP1 の機能解析

  面田彩馨, 岡田 小夏, 吉野 健一, 橘 真由美, 石野 智子, 鳥居本美, 入子 英幸

  第91回日本寄生虫学会大会, May 2022

  Poster presentation


• 熱帯熱マラリア原虫生殖母体の発育に伴うサイトストームの構造変化

  入子 英幸, 面田 彩馨, 橘 真由美, 石野 智子, 鳥居 本美

  第91回日本寄生虫学会大会, May 2022

  Poster presentation


• Protein trafficking and parasite-derived membrane structures in P. falciparum-infected erythrocytes

  Hideyuki Iriko

  The 4th Asian Congress of Protistology -internet, Nov. 2021, English

  [Invited]

  Nominated symposium


• Expression profile and immuno-localization of Skeleton Binding Protein 1 (SBP1) during gametocyte stage in Plasmodium falciparum.

  Ayaka Omoda, Jerusha Kulamahan, Nozomi Yamasaki, Mayumi Tachibana, Tomoko Ishino, Motomi Torii, Hideyuki Iriko

  The 4th Asian Congress of Protistology -internet, Nov. 2021, English

  Poster presentation


• 熱帯熱マラリア原虫生殖母体感染赤血球のMaurer's cleft局在タンパク質の解析

  面田彩馨, 岡田小夏, 橘真由美, 石野智子, 鳥居本美, 入子英幸

  第76回日本寄生虫学会西日本支部大会, Sep. 2021

  Oral presentation


• 熱帯熱マラリア原虫生殖母体期におけるPTEX複合体構成タンパク質の発現プロファイル解析

  岡田小夏, 伊坂恵里奈, 面田彩馨, 橘真由美, 石野智子, 鳥居本美, 高島英造, 坪井敬文, 入子英幸

  第 76 回日本寄生虫学会 西日本支部大会, Sep. 2021

  Oral presentation


• 熱帯熱マラリア原虫の赤血球寄生ステージに形成される膜構造

  入子 英幸

  第30回 原生生物・寄生虫・進化（PPE）セミナー, Jul. 2021


• 熱帯熱マラリア原⾍の⽣殖⺟体期における原⾍タンパク質輸送機構の解析

  面田彩馨, 橘真由美, 石野智子, 鳥居本美, 坪井敬文, 入子英幸

  第90回日本寄生虫学会 第32回日本臨床寄生虫学会 合同大会, Apr. 2021

  Poster presentation


• Skeleton binding protein 1 (SBP1) of Plasmodium falciparum is localized in Maurer’s cleft of gametocyte infected erythrocyte

  Ayaka Omoda, Jerusha Kulamahan, Nozomi Yamasaki, Mayumi Tachibana, Tomoko Ishino, Motomi Torii, Hideyuki Iriko

  Joint meeting of the Japan Society of Protistology and Korean Society of Protistologists (Kobe2020), Nov. 2020, English

  Poster presentation


• 熱帯熱マラリア原虫のSkeleton binding protein 1(SBP1)は 寄生胞膜通過前にelectron dense materialに集積する

  入子英幸, 面田彩馨, 山崎望, 石野智子, 橘真由美, 鳥居本美, 坪井敬文

  第27回分子寄生虫学ワークショップ & 第17回分子寄生虫・マラリア研究フォーラム, Aug. 2019


• 熱帯熱マラリア原虫生殖母体期におけるモーラークレフト分子の発現プロファイル解析

  面田彩馨, 山崎望, 橘真由美, 石野智子, 鳥居本美, 坪井敬文, 入子英幸

  第27回分子寄生虫学ワークショップ&第17回分子寄生虫・マラリア研究フォーラム, Aug. 2019


• 熱帯熱マラリア原虫の寄生胞膜分子の発現プロファイル解析

  入子英幸, 山崎望, 橘真由美, 石野智子, 鳥居本美, 坪井敬文

  第88回日本寄生虫学会大会（長崎市）, Mar. 2019

  Oral presentation


• 熱帯熱マラリア原虫の寄生胞膜動態の解析

  入子英幸

  近畿電顕技術情報交換会 第３９回談話会, Nov. 2018, Japanese

  Invited oral presentation


• 熱帯熱マラリア原虫の寄生胞膜分子の発現プロファイル解析

  入子英幸, 山崎望, 大槻均, 石野智子, 橘真由美, 鳥居本美, 坪井敬文

  第２６回分子寄生虫学ワークショップ／ 第１６回分子寄生虫・マラリア研究フォーラム合同大会, Sep. 2018, Japanese

  Oral presentation


• Morphological observation of parasitophorous vacuole membrane during hemoglobin uptake of Plasmodium gametocyte stages

  Iriko H, Ishino T, Otsuki H, Tachibana M, Torii M, Tsuboi T.

  14th International congress of parastiology (ICOPA 2018), Aug. 2018, English

  Poster presentation


• ETRAMP4 は熱帯熱マラリア原虫の生殖母体期に発現する寄生胞膜分子である

  入子英幸, 橘真由美, 石野智子, 鳥居本美, 大槻均, 坪井敬文

  第87回日本寄生虫学会大会（東京）, Mar. 2018, Japanese

  Oral presentation

• 日本生化学会


• 日本寄生虫学会

• Identification of novel P. falciparum placenta ligands responsible for pregnancy-associated malaria

  坪井 敬文, 橘 真由美, 入子 英幸, 伊藤 大輔

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Fund for the Promotion of Joint International Research (International Collaborative Research), Ehime University, 08 Sep. 2023 - 31 Mar. 2026


• 熱帯熱マラリア原虫生殖母体期の感染赤血球における細胞接着機構の解析

  入子 英幸

  日本学術振興会, 科学研究費助成事業 基盤研究(C), 基盤研究(C), 神戸大学, 01 Apr. 2022 - 31 Mar. 2025


• 三日熱マラリア伝搬阻止効果のある患者血漿を用いた新規ワクチン候補抗原の探索

  石野 智子, 橘 真由美, 馬場 みなみ, 鳥居 本美, 入子 英幸

  日本学術振興会, 科学研究費助成事業, 国際共同研究加速基金(国際共同研究強化(B)), Oct. 2019 - Mar. 2024

  主にアジアで流行する三日熱マラリアは、致死性の低さおよび原虫の入手が困難なことから、保健衛生や経済活動面における影響の大きさにも関わらず対策が遅れている。媒介蚊の体内でマラリア原虫の発育を止める伝搬阻止ワクチンの開発が期待されているが、未だ実用化されたものはない。本研究は、流行地の住人の血漿に 伝搬阻止効果が認められることに着目し、自然感染により獲得された伝搬阻止抗体が、どの原虫タンパク質によって誘導されたかを明らかにすることで、有効なワクチン抗原を探索することを目的とし、タイ王国の研究者と連携し共同研究として実施する。 本課題では、伝搬阻止効果を持つ患者血漿により 共通に認識されるタンパク質をプロテインアレイを用いてスクリーニングを実施する。 本年度は、3年ぶりに感染流行地のタイ王国を訪問し、マラリア診療所にて患者血液と抗体を混合し、媒介蚊に吸血させることで伝搬阻止効果を評価できた。最適な条件下で実験が行えたが、コントロールと比較して有意に伝搬を阻害する抗体はなかった。流行地株の遺伝子多型による影響か解析するために、患者由来原虫ゲノムの抽出を行った。 さらに、昨年度開発した三日熱マラリア原虫の標的分子のみを発現させたキメラ型ネズミマラリア原虫を、今年度もさらに１種類作成した。患者由来株で伝搬を抑制しなかった抗体が、標準株の配列に対して効果があるか今後解析を行う材料が得られた。新たに伝搬阻止ワクチン標的候補分子を探索する目的で、局在解析のためにネズミマラリア原虫に候補三日熱マラリア原虫分子を発現させた原虫を２種類作成した。


• Development of novel transmission blocking vaccine targeting microgamete surface antigen of Plasmodium falciparum

  鳥居 本美, 橘 真由美, 石野 智子, 入子 英幸, 伊藤 大輔, カレトン リチャード

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), Ehime University, 01 Apr. 2020 - 31 Mar. 2023

  申請者らのネズミマラリア原虫を用いた先行研究において高い伝搬阻害活性が示されたミクロガメート表面タンパク質（MiGS）の熱帯熱マラリア原虫における相同体（PfMiGS）の中で、更に高い抗原性が示された分子内領域（Region 6）を標的とする単クローン抗体の作成を継続して行なった。昨年度中にPfMiGSのRegion6の組換えタンパク質（rPfMiGS-R6）を用いて５回の免疫を行なっていた２匹のマウスに２回の追加免疫を行った後に、マウス血清を採取し、rPfMiGS-R6を抗原とするELISA法で抗体価の上昇を測定した。高い抗体価の上昇が確認されたマウス１匹を用いてハイブリドーマを作成した。単クローン抗体を産生するハイブリドーマのスクリーニングは、rPfMiGS-R6を抗原とするELISA法によって行った。３次のスクリーニングを実施した結果、rPfMiGS-R6に特異的に反応する単クローン抗体を産生する５個のハイブリドーマ株を樹立することに成功した。最も高い反応性を示した単クローン抗体のサブクラスはIgG1であった。これと並行して、単クローン抗体の抗原反応特異性をより正確に検定することを目的として、陽性コントロールとしてPfMiGSにMycタグを付加した遺伝子改変熱帯熱マラリア原虫（PfMiGS::Myc）と陰性コントロールとしてのPfMiGS欠損熱帯熱マラリア原虫（PfΔPfMiGS）の作出を行った。そして種々の条件検討を行なって、野生株の熱帯熱マラリア原虫に加え、PfMiGS::MycおよびPfΔPfMiGSの遺伝子改変原虫においても、生殖母体そして一部は生殖体まで安定的に発育させることに成功した。これらの原虫と作成した単クローン抗体を用いて、PfMiGSの発現様式などの詳細な性状解析を行うことが可能になった。


• Analysis of parasitophorous vacuole membrane protein in hemoglobin transport and metabolism of malarial parasites

  Iriko Hideyuki

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), Kobe University, Apr. 2016 - Mar. 2019, Principal investigator

  Plasmodium parasites on erythrocytes utilize hemoglobin as a source of amino acid. Uptake and transport of hemoglobin by malarial parasites are carried out through parasitophorous vacuole membrane (PVM), but the molecular mechanism has not been elucidated. In this study, I focused on the PVM protein (ETRAMP family) of P. falciparum and analyzed the localization in the membrane structure involved in hemoglobin transport. In the result, ETRAMP10.3 was found to be localized to the PVM, cytostorm and hemoglobin transport vesicles, and to be an indicator of hemoglobin transport during gametocyte stage.

  Competitive research funding


• 熱帯熱マラリア原虫のヘモグロビン取込み機構の解析

  公益財団法人 アステラス病態代謝研究会, 平成26年度 研究助成, Apr. 2015 - Mar. 2016


• Analysis of hemoglobin transport in Plasmodium falciparum

  IRIKO HIDEYUKI

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B), Grant-in-Aid for Young Scientists (B), 01 Apr. 2013 - 31 Mar. 2015, Principal investigator

  To elucidate the molecular mechanism and membrane dynamics of hemoglobin transport, I focused in ETRAMP4 (Early Transcribed Protein 4), the membrane proteins expressed in trophozoite stage of Plasmodium falciparum. By immunoelectron microscopy, ETRAMP4 localized in parasitophorous vacuole membrane and uptake by cytostomes, hemoglobin transport vesicles.

  Competitive research funding


• A study of the effect of a recombinant immunosuppressive factor from parasites and immune-inhibitory mechanisms

  FUKUMOTO Soji, IRIKO Hideyuki, OTSUKI Hitoshi

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), Tottori University, 2009 - 2011

  An immunosuppressive factor(ES90) from Spirometra erinaceieuropaei plerocercoids was cloned and the recombinant ES90 was synthesized using wheat germ cell free expression system. However, the recombinant ES90 did not inhibit nitric oxide production in macrophages. Messenger RNA of Ym1, FIZZ1, and arginase 1 were expressed in peritoneal macrophages from Trichinella spiralis-infected mice. In connection with this, 2 types of peroxiredoxin(Prx) from T. spiralis were cloned, Prx-1 mRNA expression was stage-specific


• ネズミマラリア原虫モデルを用いた寄生胞膜分子の動態解析

  大山健康財団, 第35回 大山健康財団学術研究助成, Apr. 2009 - Mar. 2010, Principal investigator


• Analysis of menbrane dynamics and identification of target signal to parasitophorous vacuole menbrane of malaria parasite.

  IRIKO Hideyuki

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B), Grant-in-Aid for Young Scientists (B), Tottori University, 2009 - 2010

  During the process of invasion, maralia parasite initiates the formation of a membrane, the so-called parasitophorous vacuole membrane (PVM). PVM is associated with host-parasite interaction. In this study, we analysed membrane dynamics and target signal to PVM in malaria parasite. We succeed in visualization of PVM and deternimation of forming period of tubulovesicular membrane network and circular clefts.


• Functional analysis of an immunosuppressive factor secreted from a parasite and its application to rheumatoid arthritis model

  FUKUMOTO Soji, IRIKO Hideyuki

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), Tottori University, 2007 - 2008

  マンソン裂頭条虫擬充尾虫(幼虫)由来の免疫抑制因子(ES90)のN末端と内部のアミノ酸配列に基づいてRT-PCR法でcDNAが増幅でき、クローニングの基礎試料が得られた。また、同じ幼虫由来の130kDaの免疫抑制因子(ES130)を精製した。ES130は活性化マクロファージが産生する3つのケモカイン(RANTES, MIP-2, IP-10)の遺伝子発現を抑制し、炎症や免疫応答の抑制への関与が推察された。


• Comprehensive screening and identification of the novel malaria transmission-blocking vaccine candidate antigens

  TSUBOI Takafumi, TAKEO Satoru

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), Ehime University, 2006 - 2007

  Malaria transmission-blocking vaccines (TBVs) prevent the transmission of malaria by inducing antibodies against antigens specifically expressed on the sexual stage parasites. Since well-characterized TBV candidates are only four, it would be necessary to identify novel TBV candidates for a successful TBV development. In order to identify the novel TBV candidates, we searched a combined dataset from genome and transcriptome databases and selected 192 genes, which are expected to be expressed only in gametocyte stage of P. falciparum. These genes were cloned into plasmids and 170 of the template cDNA clones were prepared for transcription through PCR-based procedures, followed by high throughput recombinant protein synthesis by wheat germ cell-free system. Using this approach, we succeeded in obtaining 148 recombinant proteins. After the screening of these recombinant proteins to identify novel TBV candidates with malaria patient sera harboring parasite transmission-blocking antibodies, we have identified 27 novel antigens. After subclone these candidate genes into pEU plasmid for the large-scale expression using the wheat germ cell-free system, we have expressed and affinity purified 22 targets. In order to obtain antisera, we immunized these proteins into mice. After the confirmation of the immunoreactivity of these antisera against parasites, we examined the transmission-blocking efficacy of the sera. Finally we identified the two novel parasite antigens, which induced transmission-blocking antibodies in mice. Accordingly, this approach will be useful for the novel transmission-blocking vaccine candidate discovery.


• 病原微生物が発現する宿主細胞認識分子のハイスループットな同定法の開発

  坪井 敬文, 竹尾 暁, 入子 英幸

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Exploratory Research, Grant-in-Aid for Exploratory Research, Ehime University, 2005 - 2006

  近年、多くの病原微生物のゲノム塩基配列が決定されているが、タンパク質の機能に関しては未だに得られる情報は少ない。核酸代謝・アミノ酸代謝といった生命現象に普遍的な分子は、生物全般で保存されており解析も比較的容易であるが、病原微生物の病原性に関与する分子、中でも感染の成立時に働く宿主細胞認識分子は病原微生物に固有のものが多く、ワクチンや創薬の標的であるにもかかわらず研究が遅れている。そこで我々は、病原微生物の宿主細胞認識分子をゲノムワイドに同定する手法の開発を目的として本研究を開始した。昨年度は、複雑な生活環を持ち多くの宿主細胞認識分子を持つと考えられる熱帯熱マラリア原虫の遺伝子約400個をモデルとして、コムギ無細胞タンパク質合成法を応用することにより、それらの約70%をGFP融合タンパク質として発現できた。本年度は、その原虫組換えタンパク質のレセプターとなるヒト赤血球膜ベジクルの作製を試みたが、均一なベジクルの作製は困難であった。そこで一分子蛍光分析システムを応用したレセプター・リガンドの同定の一例として、マラリア患者血清を用いた抗原抗体反応の測定を試みた。その結果、上記GFP融合原虫タンパク質の内約100種類と、患者血清を用いて検討した結果、3種類の原虫タンパク質がヒト血清中の抗体と反応し、抗原性を有していることが明らかとなった。したがって、本法は病原微生物と宿主分子間の結合をハイスループットに同定できる手法となりうることが示唆された。


• High-throughput screening of novel malaria vaccine candidates using human immune sera

  TSUBOI Takafumi, TAKEO Satoru, IRIKO Hideyuki

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), Ehime University, 2004 - 2006

  Malaria remains one of the leading causes of both morbidity and mortality in humans residing in the tropical countries. The evidence of increasing resistance of the Plasmodium falciparum parasite to chemotherapeutic agents highlights the critical need for an effective vaccine. After the establishment of malaria genome database, we have now free access to the genome data to search for novel vaccine candidates. However, one of the bottlenecks for the malaria vaccine research is the difficulty of the recombinant protein expression using conventional methods. We applied a high-throughput protein production method based on the wheat germ cell-free system to the malaria vaccine research. To identify novel malaria vaccine candidates, we selected and cloned more than 180 genes which are expected to be expressed in merozoite stage, then prepared transcription templates through PCR-based high throughput procedures, followed by protein synthesis by wheat germ cell-free system. Using this approach, we succeeded in obtaining 149 recombinant merozoite proteins. At the same time, we successfully obtained approximately 30 human immune sera from asymptomatic villagers living along the Thai-Myanmar border, and approximately 30 symptomatic malaria patient sera from hospital in Bangkok, Thailand. All human serum samples used in this study were reviewed and approved by the Institutional Ethics Committee of the Thai Ministry of Public Health and of the Ehime University, Japan. Finally, we tried to screen these recombinant proteins for identifying novel malaria vaccine candidates with five cases of the malaria immune sera by ELISA. As a result of this preliminary screening, we identified ten merozoite proteins as antigens. Accordingly, this strategy using wheat germ cell-free system will be a major breakthrough in the novel malaria vaccine candidate discovery research.


• Expression of erythrocyte binding protein in Plasmodium falciparum merozoites isolated from endemic area

  TORII Motomi, MATSUDA Syouji, KANEKO Osamu, TSUBOI Takafumi, IRIKO Hideyuki

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), Ehime University, 2001 - 2002

  Mutant erythrocyte that lacked certain proteins on the surface were frequently observed in the malaria endemic areas, and some of them were believed to be generated by the selective advantage against malaria infection. However, Plasmodium falciparum have an ability to invade many types of erythrocyte including these mutant erythrocytes. The molecular base of this ability of P.falciparum could be resulted by the erythrocyte-binding proteins encoded in the multi-gene family involved in the invasion steps. In this study, we explored the possibility if P.falciparum regulated the expression of these multi-gene family in order to overcome the erythrocyte polymorphism by quantitate the transcription and protein expression level of each members of the multi-gene family, PfRhopH1. Firstly, we designed a panel of oligonucleotide primers for real-time PCR method with SYBR green. Complementary DNA was made from the 3D7 clone of P.falciparum and used to make plasmids containing the real-time PCR targets for each member. These plasmids were used to create the standard curve. P.falciparum field samples were collected in the malaria endemic area in Thailand and total RNA were extracted. Simultaneously blood smear were made on the glass slides for the IFA analysis for the protein expression. In order to check the protein expression level, we successfully generated anti-PfRhopHl_2, 3.1, 9 specific sera. Difference in the protein expression was observed among the culture-adapted P. falciparum clones.