title: Nitric oxide as an antimicrobial molecule against Vibrio harveyi infection in the hepatopancreas of Pacific white shrimp, Litopenaeus vannamei.
abstract: Nitric oxide (NO) is a key effector molecule produced in the innate immune systems of many species for antimicrobial defense. However, how NO production is regulated during bacterial infection in invertebrates, especially crustaceans, remains poorly understood. Vibrio harveyi, a Gram-negative marine pathogen, is among the most prevalent and serious threats to the world's shrimp culture industry. Its virulence typically manifests itself through shrimp hepatopancreas destruction. In the current study, we found that NO generated by an in vitro donor system (NOC-18) could rapidly and effectively kill V. harveyi. In addition, injection of heat-killed V. harveyi increased the concentration of NO/nitrite and the mRNA expression of nitric oxide synthase (NOS) in the hepatopancreas of Pacific white shrimp (Litopenaeus vannamei), the commercially most significant shrimp species. Live V. harveyi challenge also induced NO/nitrite production and NOS gene expression in primary L. vannamei hepatopancreatic cells in a time- and dose-dependent manner. Co-incubation of l-NAME, an inhibitor selective for mammalian constitutive NOSs, dose-dependently blocked V. harveyi-induced NO/nitrite production, without affecting V. harveyi-induced NOS mRNA expression. Furthermore, l-NAME treatment significantly increased the survival rate of infecting V. harveyi in cultured primary hepatopancreatic cells of L. vannamei. As a whole, we have demonstrated that endogenous NO produced by L. vannamei hepatopancreatic cells occurs in enzymatically regulated manners and is sufficient to act as a bactericidal molecule for V. harveyi clearance.
authors.affiliation: CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Key Laboratory of Applied Marine Biology of Guangdong Province and Chinese Academy of Sciences (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China. Electronic address: chan1010@scsio.ac.cn.
authors.forename: Ting
authors.initials: T
authors.lastname: Chen
authors.affiliation: Department of Chemistry, University of Hong Kong, Hong Kong, China. Electronic address: wongnk@gmail.com.
authors.forename: Nai-Kei
authors.initials: NK
authors.lastname: Wong
authors.affiliation: CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Key Laboratory of Applied Marine Biology of Guangdong Province and Chinese Academy of Sciences (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China. Electronic address: jiangxiao4367@126.com.
authors.forename: Xiao
authors.initials: X
authors.lastname: Jiang
authors.affiliation: CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Key Laboratory of Applied Marine Biology of Guangdong Province and Chinese Academy of Sciences (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; University of Chinese Academy of Sciences, Beijing, China. Electronic address: luoxingzky@163.com.
authors.forename: Xing
authors.initials: X
authors.lastname: Luo
authors.affiliation: CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Key Laboratory of Applied Marine Biology of Guangdong Province and Chinese Academy of Sciences (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China. Electronic address: lpzhang@scsio.ac.cn.
authors.forename: Lvping
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, University of Hong Kong, Hong Kong, China. Electronic address: yangdan@hku.hk.
authors.forename: Dan
authors.initials: D
authors.lastname: Yang
authors.affiliation: CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Key Laboratory of Applied Marine Biology of Guangdong Province and Chinese Academy of Sciences (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China. Electronic address: rosemary166@sina.com.
authors.forename: Chunhua
authors.initials: C
authors.lastname: Ren
authors.affiliation: CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Key Laboratory of Applied Marine Biology of Guangdong Province and Chinese Academy of Sciences (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China. Electronic address: hucq@scsio.ac.cn.
authors.forename: Chaoqun
authors.initials: C
authors.lastname: Hu
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D017756:Aquaculture; D015971:Gene Expression Regulation, Enzymologic / Q000276:immunology*; D043143:Hepatopancreas / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D033561:Penaeidae / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D016019:Survival Analysis; D014733:Vibrio / Q000276:immunology*
chemical_list: D009569:Nitric Oxide; D019001:Nitric Oxide Synthase
keywords: Antimicrobial molecule; Hepatopanfcreas; Litopenaeus vannamei; Nitric oxide; Vibrio harveyi