Phage therapy against Vibrio parahaemolyticus infection in the whiteleg shrimp (Litopenaeus vannamei) larvae

Vibrio parahaemolyticus is an important cause of disease, mortality, and economical losses in the shrimp aquaculture industry. Bacteriophages are natural bio-controlling agents, broadly recognized for their ability to reduce pathogen populations. Hence, in the present study, we evaluated the effectiveness of phage therapy in the prevention and control of vibriosis in Litopenaeus vannamei. Vibriosis was induced in shrimp larvae with 2×10⁶CFUmL^-1 of V. parahaemolyticus. The infected larvae were treated with different doses of selected phages and their efficacy was evaluated at different times after their application. Results revealed that selected lytic phages (A3S and Vpms1) are effective to reduce mortality caused by V. parahaemolyticus. In both cases, the early application (at 6h post-infection) was effective to avoid mortality. Low multiplicity of infection (MOI) values (<0.1) were enough to counteract V. parahaemolyticus infection. Delayed phage applications (>6h post-infection) hindered mortality and the progress of infection. This study provides the basis for the use of bacteriophages in the prevention and control of V. parahaemolyticus in shrimps.