Small creatures use small RNAs to direct antiviral defenses

Abstract

Antiviral RNA silencing has been recognized as an important defense mechanism in arthropods against RNA viruses. However, the role of this pathway in DNA virus infection remains largely unexplored. A report in this issue of the European Journal of Immunology [Eur J Immunol 2012. XXXX] provides new insight into the role of RNA silencing in antiviral defense against DNA viruses. Huang and Zhang found that the dsDNA virus White Spot Syndrome virus, an agriculturally important pathogen of shrimp, is targeted by the shrimp RNA silencing machinery via the production of virus-derived siRNAs. Furthermore, the authors show that the RNA silencing pathway, and crucially, Dicer-2, is important for restricting viral infection. This study provides novel insights not only into shrimp antiviral defenses but also potentially into antiviral immunity against DNA viruses in a larger spectrum of hosts, as discussed in this Commentary. Furthermore, this study may contribute to the future development of immune-based therapeutics to combat viral pathogens, not only in aquaculture, but also in insect vectors of human diseases.

MicroRNAs as mediators of insect host–pathogen interactions and immunity

“…For other types of small RNAs and their role in anti-viral responses, readers are referred to recent reviews (e.g. Sabin and Cherry, 2013;Bronkhorst and van Rij, 2014).…”

Antiviral Defense and Innate Immune Memory in the Oyster

“…When generated, viRNAs are loaded into a multi-subunit RNA-induced silencing complex (RISC), where they mediate sequence-specific cleavage of the viral RNA within the cell [ 19 ]. Insects and nematodes primarily utilize viRNAs to combat viral infection [ 20 ], whereas vertebrates cells instead use a protein-based defense called the type I interferon (IFN) system as the major innate antiviral response [ 15 , 21 ]. Viral infection of a vertebrate cell triggers the activation of a number of pattern recognition receptors (PRRs), with subsequent transcriptional activation of a family of IFN genes [ 15 ].…”

Viruses and antiviral immunity in Drosophila

“…Indeed, insects with compromised immune systems can succumb to typically non-pathogenic infections (Carré-Mlouka et al, 2007; Costa et al, 2009a; Sabin et al, 2009; van Mierlo et al, 2012; Zambon et al, 2005), suggesting that insect immunity is active and protective during these infections. We are just beginning to decipher the innate mechanisms by which arthropods, including vectors of human diseases and commercially important species (e.g., honeybees, silkworms, and shrimp), can combat viral pathogens (Evans and Spivak, 2010; Flegel, 2009; Johnson et al, 2008; Sabin and Cherry, 2013). This lack of knowledge is due, in part to the difficult nature of performing molecular and genetic studies in pertinent arthropod species, many of which cannot be reared in the laboratory.…”