Spawning of female Black tiger shrimp (Penaeus monodon ) is not impacted by muscle injection of dsRNA targeted to gill-associated virus

Abstract

The ability of domesticated Penaeus monodon, Black Tiger shrimp, to spawn following tail-muscle injection of dsRNA was examined. Ablated domesticated female broodstock infected subclinically with gill-associated virus (GAV) were injected with saline or a cocktail of five-dsRNAs targeting different regions in the GAV ORF1a/1b gene. To track changes in GAV infection loads, TaqMan real-time PCR was used to quantify mean viral RNA amounts in each of three pleopod clips collected at the time of injection (Day 0) and either immediately after a female spawned or on Day 11 when the trial was terminated. Over the trial, 4 of 19 (21%) saline-injected shrimp spawned and 12 of 25 (48%) dsRNA-injected shrimp spawned, with one spawning twice. Egg numbers varied from 25 600 to 459 800 for the saline-injected shrimp and from 4900 to 213 900 for the dsRNA-injected shrimp. Of these, one of the four egg batches hatched from saline-injected shrimp and 9 of the 13 egg batches hatched from dsRNA-injected shrimp. While variable, egg numbers and hatch rates recorded were typical of those obtained from domesticated broodstock at the commercial hatchery and particularly among females previously spawned. Mean GAV RNA amounts detected in pleopod samples increased in five of the eight saline-injected shrimp tested by 1.6–227.4-fold and decreased in 12 of the 15 ds-RNA-injected shrimp tested by −1.1 to −45.1-fold. The study demonstrated that tail-muscle injection of GAV-specific dsRNA does not adversely impact the ability of P. monodon to spawn.