Prophylactic evaluation of an RNA interference (RNAi) bio-drug against White Spot Syndrome Virus (WSSV) in commercial lines of Litopenaeus vannamei broodstock

The white spot syndrome virus (WSSV) is a constant threat for white shrimp (L. vannamei) aquaculture since it can cause major economic losses. One of the biotechnologies that have gained relevance to prevent WSSV infections are the bio-drugs based on RNA interference (RNAi) mechanisms, which can be initiated by the exogenous application of double-stranded RNA (dsRNA) that is administrated to shrimp for blocking the expression of some viral gene. In the present work, we made a small-scale evaluation of a bio-drug (Bfvt) constructed from a specific dsRNA against the viral gene associated to orf89 from WSSV, as prophylactic treatment in L. vannamei broodstock. The Bfvt was administrated intramuscularly to shrimp broodstock from two families (B and C) with natural resistance to WSSV, which were subsequently challenged with the virus through two ways of infection (intramuscular and per os). The results show that although both families presented a similar resistance to WSSV, the administration of Bfvt decreased the viral load and increased the survival of shrimp challenged with the virus, especially those that were intramuscularly infected. We conclude that the intramuscular administration of Bfvt is efficient and viable as strategy to prevent the WSSV infection in shrimp broodstock confined to maturation.