title: Suppression of shrimp melanization during white spot syndrome virus infection.
abstract: The melanization cascade, activated by the prophenoloxidase (proPO) system, plays a key role in the production of cytotoxic intermediates, as well as melanin products for microbial sequestration in invertebrates. Here, we show that the proPO system is an important component of the Penaeus monodon shrimp immune defense toward a major viral pathogen, white spot syndrome virus (WSSV). Gene silencing of PmproPO(s) resulted in increased cumulative shrimp mortality after WSSV infection, whereas incubation of WSSV with an in vitro melanization reaction prior to injection into shrimp significantly increased the shrimp survival rate. The hemolymph phenoloxidase (PO) activity of WSSV-infected shrimp was extremely reduced at days 2 and 3 post-injection compared with uninfected shrimp but was fully restored after the addition of exogenous trypsin, suggesting that WSSV probably inhibits the activity of some proteinases in the proPO cascade. Using yeast two-hybrid screening and co-immunoprecipitation assays, the viral protein WSSV453 was found to interact with the proPO-activating enzyme 2 (PmPPAE2) of P. monodon. Gene silencing of WSSV453 showed a significant increase of PO activity in WSSV-infected shrimp, whereas co-silencing of WSSV453 and PmPPAE2 did not, suggesting that silencing of WSSV453 partially restored the PO activity via PmPPAE2 in WSSV-infected shrimp. Moreover, the activation of PO activity in shrimp plasma by PmPPAE2 was significantly decreased by preincubation with recombinant WSSV453. These results suggest that the inhibition of the shrimp proPO system by WSSV partly occurs via the PmPPAE2-inhibiting activity of WSSV453.
authors.affiliation: From the Center of Excellence for Molecular Biology and Genomics of Shrimp, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Jantiwan
authors.initials: J
authors.lastname: Sutthangkul
authors.affiliation: From the Center of Excellence for Molecular Biology and Genomics of Shrimp, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand, the National Center for Genetic Engineering and Biotechnology, National Science and Technology, Development Agency, Klong Luang, Pathumthani 12120, Thailand, and.
authors.forename: Piti
authors.initials: P
authors.lastname: Amparyup
authors.affiliation: the National Center for Genetic Engineering and Biotechnology, National Science and Technology, Development Agency, Klong Luang, Pathumthani 12120, Thailand, and the Center of Excellence for Shrimp Molecular Biology and Biotechnology, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Walaiporn
authors.initials: W
authors.lastname: Charoensapsri
authors.affiliation: the National Center for Genetic Engineering and Biotechnology, National Science and Technology, Development Agency, Klong Luang, Pathumthani 12120, Thailand, and the Center of Excellence for Shrimp Molecular Biology and Biotechnology, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Saengchan
authors.initials: S
authors.lastname: Senapin
authors.affiliation: the National Center for Genetic Engineering and Biotechnology, National Science and Technology, Development Agency, Klong Luang, Pathumthani 12120, Thailand, and the Center of Excellence for Shrimp Molecular Biology and Biotechnology, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Kornsunee
authors.initials: K
authors.lastname: Phiwsaiya
authors.affiliation: From the Center of Excellence for Molecular Biology and Genomics of Shrimp, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand, anchalee.k@chula.ac.th.
authors.forename: Anchalee
authors.initials: A
authors.lastname: Tassanakajon
mesh_terms: D000818:Animals; D004156:Catechol Oxidase / Q000378:metabolism; D004792:Enzyme Precursors / Q000378:metabolism; D020868:Gene Silencing; D006458:Hemolymph / Q000276:immunology / Q000378:metabolism / Q000821:virology; D054884:Host-Pathogen Interactions / Q000235:genetics / Q000276:immunology; D008543:Melanins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D033561:Penaeidae / Q000235:genetics / Q000378:metabolism* / Q000821:virology; D060066:Protein Interaction Maps / Q000235:genetics; D012697:Serine Endopeptidases / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D046848:White spot syndrome virus 1 / Q000201:enzymology* / Q000276:immunology / Q000472:pathogenicity
chemical_list: D004792:Enzyme Precursors; D008543:Melanins; D014764:Viral Proteins; C038451:pro-phenoloxidase; D004156:Catechol Oxidase; D012697:Serine Endopeptidases; C022435:prephenoloxidase-activating enzyme
keywords: Immunology; Invertebrate; Protein-Protein Interaction; Proteolytic Enzyme; Virus