Antiviral immunity induced by double stranded RNA in a marine invertebrate

Adaptive immunity and interferon-based antiviral responses are evolutionarily restricted to the jawed vertebrates, suggesting that invertebrates rely on unique mechanisms to fight viral infections. The studies presented here demonstrate that the marine shrimp, Litopenaeus vannamei, possesses two mechanisms of antiviral immunity that are induced by double stranded RNA (dsRNA). One such mechanism is of broad viral spectrum, independent of the sequence of the dsRNA inducer, and accompanied by a significant reprogramming of the transcriptome. The second antiviral mechanism relies on gene silencing phenomena that are analogous to dsRNA-mediated interference (RNAi). Transcriptomic analyses of the response to virus and to dsRNA suggest that the oxidative stress response, the regulation of cell adhesion and motility, and the activation of intracellular trafficking and secretion play roles in antiviral phenomena in shrimp. Taken together, the results from these studies indicate that the immune system of invertebrates relies on recognition of dsRNA to sense viral infections, leading to the simultaneous activation of innate immunity and of adaptive antiviral gene silencing.