title: RNAi-based inhibition of infectious myonecrosis virus replication in Pacific white shrimp Litopenaeus vannamei.
abstract: Disease in Pacific white shrimp Litopenaeus vannamei caused by the infectious myonecrosis virus (IMNV) causes significant socioeconomic impacts in infection-prone shrimp aquaculture regions. The use of synthetic dsRNA to activate an RNA interference (RNAi) response is being explored as a means of disease prophylaxis in farmed shrimp. Here, survival was tracked in L. vannamei injected with long synthetic dsRNAs targeted to IMNV open reading frame (ORF) 1a, ORF1b, and ORF2 genome regions prior to injection challenge with IMNV, and real-time RT-PCR was used to track the progress of IMNV infection and mRNA expression levels of the host genes sid1, dicer2, and argonaute2. Injection of dsRNAs targeting the ORF1a and ORF1b genes but not the ORF2 gene strongly inhibited IMNV replication over a 3 wk period following IMNV challenge, and resulted in 90 and 83% shrimp survival, respectively. Host gene mRNA expression data indicated that the Sid1 protein, which forms a transmembrane channel involved in cellular import/export of dsRNA, increased in abundance most significantly in shrimp groups that were most highly protected by virus-specific dsRNA injection. Subclinical IMNV infections present in the experimental L. vannamei used increased markedly in the 2 d between injection of any of the 4 virus-specific or non-specific dsRNAs tested and IMNV challenge. While handling and injection stress are implicated in increasing IMNV replication levels, the underlying molecular factors that may have been involved remain to be elucidated.
authors.affiliation: Laboratório de Biologia Molecular, Instituto de Ciências Biológicas (ICB), Universidade Federal de Rio Grande (FURG), Av. Itália, Km 8, CEP 96203-900, Rio Grande, RS, Brazil.
authors.forename: Rubens Galdino
authors.initials: RG
authors.lastname: Feijó
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Maggioni
authors.forename: Pedro Carlos
authors.initials: PC
authors.lastname: Cunha Martins
authors.forename: Keuly Ladislau
authors.initials: KL
authors.lastname: de Abreu
authors.forename: João Mafaldo
authors.initials: JM
authors.lastname: Oliveira-Neto
authors.forename: Cristhiane
authors.initials: C
authors.lastname: Guertler
authors.forename: Emily Bruna
authors.initials: EB
authors.lastname: Justino
authors.forename: Luciane Maria
authors.initials: LM
authors.lastname: Perazzolo
authors.forename: Luis Fernando
authors.initials: LF
authors.lastname: Marins
mesh_terms: D000818:Animals; D015967:Gene Expression Regulation, Viral; D054884:Host-Pathogen Interactions; D033561:Penaeidae / Q000821:virology*; D034622:RNA Interference; D012333:RNA, Messenger; D012367:RNA, Viral / Q000378:metabolism*; D013997:Time Factors; D019196:Totiviridae / Q000235:genetics* / Q000502:physiology*; D014779:Virus Replication / Q000502:physiology
chemical_list: D012333:RNA, Messenger; D012367:RNA, Viral