title: Double-dose β-glucan treatment in WSSV-challenged shrimp reduces viral replication but causes mortality possibly due to excessive ROS production.
abstract: In our research efforts to reduce the impact of white spot syndrome virus (WSSV) disease outbreaks in shrimp aquaculture, we studied the effect of β-glucan administration to activate the prophenoloxidase (proPO) enzymatic cascade prior to WSSV challenge. Injection of a single dose of β-glucan (5 μg/g) prior to WSSV challenge resulted in activation of the proPO system and reduced shrimp mortality (25-50%) when compared to controls (100%). By contrast, no significant reduction was observed using yellow head virus (YHV) in a similar protocol. We subsequently hypothesized that administration of a second dose of β-glucan after WSSV challenge might reduce shrimp mortality further. Surprisingly, the opposite occurred, and mortality of the WSSV-infected shrimp increased to 100% after the second β-glucan dose. Both immunofluorescence and RT-PCR assays revealed low WSSV levels in hemocytes of shrimp collected after the second dose of β-glucan administration, suggesting that the cause of increased mortality was unlikely to be increased WSSV replication. We found from measured phenoloxidase acitivity (PO) and H2O2 production that the higher mortality may have resulted from a combination of WSSV infection plus over-production of reactive oxygen species (ROS) stimulated by two doses of β-glucan. Thus, caution may be prudent in continuous or prolonged activation of the shrimp immune system by β-glucan administration lest it exacerbate shrimp mortality in the event of WSSV infection.
authors.affiliation: Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, RamaVI Rd., Bangkok 10400, Thailand; Department of Biotechnology, Faculty of Science, Mahidol University, RamaVI Rd., Bangkok 10400, Thailand.
authors.forename: Siripong
authors.initials: S
authors.lastname: Thitamadee
authors.affiliation: Shrimp-virus interaction laboratory (ASVI), National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Rama VI Rd., Bangkok 10400, Thailand.
authors.forename: Jiraporn
authors.initials: J
authors.lastname: Srisala
authors.affiliation: Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, RamaVI Rd., Bangkok 10400, Thailand.
authors.forename: Suparat
authors.initials: S
authors.lastname: Taengchaiyaphum
authors.affiliation: Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, RamaVI Rd., Bangkok 10400, Thailand; Department of Biotechnology, Faculty of Science, Mahidol University, RamaVI Rd., Bangkok 10400, Thailand; Shrimp-virus interaction laboratory (ASVI), National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Rama VI Rd., Bangkok 10400, Thailand. Electronic address: kallaya@biotec.or.th.
authors.forename: Kallaya
authors.initials: K
authors.lastname: Sritunyalucksana
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005455:Fluorescent Antibody Technique; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000378:metabolism; D033561:Penaeidae / Q000276:immunology* / Q000378:metabolism / Q000821:virology*; D016133:Polymerase Chain Reaction; D011509:Proteoglycans; D017382:Reactive Oxygen Species / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects*; D046848:White spot syndrome virus 1 / Q000187:drug effects* / Q000502:physiology; D047071:beta-Glucans / Q000494:pharmacology*
chemical_list: D000276:Adjuvants, Immunologic; D011509:Proteoglycans; D017382:Reactive Oxygen Species; D047071:beta-Glucans; C010770:polysaccharide-K; D014442:Monophenol Monooxygenase
keywords: Prophenoloxidase (proPO); Reactive oxygen species (ROS); White spot syndrome virus (WSSV); β-glucan