title: Proteomic analysis of Singapore grouper iridovirus envelope proteins and characterization of a novel envelope protein VP088.
abstract: Singapore grouper iridovirus (SGIV) is an enveloped virus causing heavy economic losses to marine fish culture. The envelope fractions of SGIV were separated from the purified virions by Triton X-100 treatment, and subjected to 1-DE-MALDI-TOF/TOF-MS/MS and LC-MALDI-TOF/TOF-MS/MS analysis. A total of 19 virus-encoded envelope proteins were identified in this study and 73.7% (13/17) of them were predicted to be membrane proteins. Three viral envelope proteins were uniquely identified by 1-DE-MALDI, whereas another ten proteins were identified only by LC-MALDI, with six proteins identified by both workflows. VP088 was chosen as a representative of proteomic identification and characterized further. VP088 was predicted to be a viral transmembrane envelope protein which contains two RGD (Arg-Gly-Asp) motifs, three transmembrane domains, and five N-glycosylation sites. VP088 gene transcript was first detected at 12 h p.i. and reached the peak at 48 h p.i. Combined with the drug inhibition assay, VP088 gene was identified as a late (L) gene. Recombinant VP088 (rVP088) was expressed in Escherichia coli, and the specific antiserum against rVP088 was raised. VP088 was proved to be a viral envelope protein by Western blot and immunoelectron microscopy (IEM). Furthermore, rVP088 can bind to a 94 kDa host cell membrane protein, suggesting that VP088 might function as an attaching protein. Neutralization assay also suggested that VP088 is involved in SGIV infection. This study will lead to a better understanding of molecular mechanisms of the iridoviral pathogenesis and virus-host interactions.
authors.affiliation: Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Guangzhou, P R China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Zhou
authors.forename: Qingjiao
authors.initials: Q
authors.lastname: Wan
authors.forename: Youhua
authors.initials: Y
authors.lastname: Huang
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Huang
authors.forename: Jianhao
authors.initials: J
authors.lastname: Cao
authors.forename: Lili
authors.initials: L
authors.lastname: Ye
authors.forename: Teck-Kwang
authors.initials: TK
authors.lastname: Lim
authors.forename: Qingsong
authors.initials: Q
authors.lastname: Lin
authors.forename: Qiwei
authors.initials: Q
authors.lastname: Qin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001492:Bass / Q000821:virology; D015153:Blotting, Western; D002853:Chromatography, Liquid; D017994:Iridovirus / Q000737:chemistry*; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D040901:Proteomics / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D014759:Viral Envelope Proteins