Probiotic bacteria (Lactobacillus plantarum) expressing specific double-stranded RNA and its potential for controlling shrimp viral and bacterial diseases

We engineered probiotic bacteria, Lactobacillus plantarum, to produce specific double-stranded (ds)RNA for viral inhibition in penaeid shrimp. When supplemented in feed, the developed strain should offer specific viral disease resistance and still remain other beneficial effects on shrimp health against other bacterial pathogens. The pWH1520 expression vector was constructed to encode hairpin RNA targeting shrimp yellow head virus (YHV) in L. plantarum. The quantity of YHV-specific dsRNA (dsYHV) was approximately 1.66 ± 0.25 ng from 7 × 10¹¹ CFU of L. plantarum. Feeding shrimp with the probiotic expressing dsYHV (at 10¹¹ CFU g⁻¹ feed) for 5 days prior to YHV challenge provided shrimp partial protection against YHV. In vitro agar well diffusion analysis revealed that both wild-type and transformed L. plantarum inhibited growth of Vibrio parahaemolyticus, the shrimp pathogen responsible for acute hepatopancreatic necrosis disease (AHPND) and early mortality syndrome (EMS). When tested in shrimp by immersion method, both L. plantarum strains (at 10⁷ CFUs ml⁻¹ seawater) also provided shrimp protection against V. parahaemolyticus. In conclusion, this study suggested the potential of the dsRNA-expressed L. plantarum for promoting shrimp health against the pathogenic virus. In addition, engineering L. plantarum for dsRNA production did not alter the probiotic’s intrinsic antibacterial property, and therefore, the developed strain can be used to protect shrimp against the important bacterial pathogen, V. parahaemolyticus causing AHPND/EMS.