title: Anti-melanization mechanism of the white spot syndrome viral protein, WSSV453, via interaction with shrimp proPO-activating enzyme, PmproPPAE2.
abstract: Inhibition of the host melanization reaction, activated by the prophenoloxidase activating (proPO) system, is one of the crucial evasion strategies of pathogens. Recently, the shrimp pathogen, white spot syndrome virus (WSSV), was found to inhibit melanization in the shrimp Penaeus monodon. The viral protein WSSV453 was previously shown to interact with PO-activating enzyme 2 (PmPPAE2) and reported to be involved in suppressing the shrimp melanization response after WSSV infection. Here, we characterized how WSSV453 inhibits melanization. WSSV453 is a non-structural viral protein, which was first detected in shrimp haemocytes at 6 hours post-infection (hpi) by WSSV and in shrimp plasma at 24 hpi. We produced recombinant proteins for three components of the P. monodon proPO system: PmproPPAE2, PmproPO1 and PmproPO2. Functional assays showed that active PmPPAE2 processed PmproPO1 and 2 to produce functional PO. Incubation of WSSV453 with PmproPPAE2 dose-dependently reduced PmPPAE2 activity toward PmPO1 or PmPO2. In contrast, WSSV453 had no effect on activated PmPPAE2. The addition of active PmPPAE2 to WSSV-infected shrimp plasma at day 2 post-infection also rescued PO activity. Taken together, these results indicate that the anti-melanization activity of WSSV is due to WSSV453, which interacts with PmproPPAE2 and interferes with its activation to active PmPPAE2.
authors.affiliation: Center of Excellence for Molecular Biology and Genomics of Shrimp, Department of Biochemistry, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330, Thailand.
authors.forename: Jantiwan
authors.initials: J
authors.lastname: Sutthangkul
authors.affiliation: National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), 113 Paholyothin Road, Klong1, Klong Luang, Pathumthani 12120, Thailand.
authors.forename: Piti
authors.initials: P
authors.lastname: Amparyup
authors.affiliation: Department of Entomology, University of Georgia, Athens, GA 30602, USA.
authors.forename: Jai-Hoon
authors.initials: JH
authors.lastname: Eum
authors.affiliation: Department of Entomology, University of Georgia, Athens, GA 30602, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Strand
authors.affiliation: Center of Excellence for Molecular Biology and Genomics of Shrimp, Department of Biochemistry, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330, Thailand.
authors.forename: Anchalee
authors.initials: A
authors.lastname: Tassanakajon
mesh_terms: D000818:Animals; D054884:Host-Pathogen Interactions; D033561:Penaeidae / Q000201:enzymology*; D025941:Protein Interaction Mapping; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D046848:White spot syndrome virus 1 / Q000502:physiology*
chemical_list: D011994:Recombinant Proteins; D017361:Viral Nonstructural Proteins; D012697:Serine Endopeptidases; C022435:prephenoloxidase-activating enzyme