title: Characterization of newly revealed sequences in the infectious myonecrosis virus genome in Litopenaeus vannamei.
abstract: Infectious myonecrosis virus (IMNV) causes significant economic losses in farmed shrimp, where associated mortality in ponds can reach 70 %. To explore host/pathogen interactions, a next-generation sequencing approach using lymphoid organ tissue from IMNV-infected Litopenaeus vannamei shrimp was conducted. Preliminary sequence assembly of just the virus showed that there were at least an additional 639 bp at the 5' terminus and 23 nt at the 3' terminus as compared with the original description of the IMNV genome (7561 nt). Northern blot and reverse transcription-PCR analysis confirmed the presence of novel sequence at both ends of the genome. Using 5' RACE, an additional 4 nt were discovered; 3' RACE confirmed the presence of 22 bp rather than 23 bp of sequence. Based on these data, the IMNV genome is 8226 bp in length. dsRNA was used to trigger RNA interference (RNAi) and suppress expression of the newly revealed genome sections at the 5' end of the IMNV genome in IMNV-infected L. vannamei. An RNAi trigger targeting a 376 bp length of the 5' UTR did not improve survival of infected shrimp. In contrast, an RNAi trigger targeting a 381 bp sequence in ORF1 improved survival to 82.2 % as compared with 2.2 % survival in positive control animals. These studies revealed the importance of the new genome sections to produce high-titre infection, and associated disease and mortality, in infected shrimp.
authors.affiliation: 1Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, IA 50011, USA.
authors.forename: Duan S
authors.initials: DS
authors.lastname: Loy
authors.affiliation: 2Department of Entomology, Iowa State University, Ames, IA 50011, USA.
authors.forename: Sijun
authors.initials: S
authors.lastname: Liu
authors.affiliation: 3Harrisvaccines, Inc., Ames, IA 50010, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Mogler
authors.affiliation: 1Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, IA 50011, USA.
authors.forename: J
authors.initials: J
authors.lastname: Dustin Loy
authors.affiliation: 1Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, IA 50011, USA.
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Blitvich
authors.affiliation: 2Department of Entomology, Iowa State University, Ames, IA 50011, USA 1Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, IA 50011, USA.
authors.forename: Lyric C
authors.initials: LC
authors.lastname: Bartholomay
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D016679:Genome, Viral; D008969:Molecular Sequence Data; D033561:Penaeidae / Q000821:virology*; D012327:RNA Virus Infections; D012367:RNA, Viral / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D016019:Survival Analysis; D019196:Totiviridae / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D012367:RNA, Viral