Long‐lasting Effect Against White Spot Syndrome Virus in Shrimp Broodstock, Litopenaeus vannamei, by LvRab7 Silencing

Abstract

The white spot syndrome virus (WSSV) remains the most devastating viral pathogen of shrimp culture worldwide. Gene silencing by RNA interference (RNAi) using double stranded RNA (dsRNA) has been considered a powerful tool for conferring protection against WSSV when viral genes are silenced, as documented in several shrimp species. However, this effect is not long lasting. Our results provide the first evidence that long-term silencing of the LvRab7 endogen produced antiviral effect against WSSV, which endured at least 21 d after dsRNA treatment (dat). Until now, the most efficient way to implement RNAi with dsRNA into the shrimp is by injection. Consequently, its application to broodstock in hatcheries is possible, minimizing the risk of vertical transmission of the virus. We show that the expression of Rab7 in hemocytes is lowest at 2 dat and finally recovers to basal status. In contrast, in gills and pleopods, gene expression silencing continued for at least 21 d. We challenged Litopenaeus vannamei broodstock with WSSV at 7, 14, or 21 dat reaching mortality rates of 0, 40, and 27%, respectively. In conclusion, the LvRab7 gene silencing is progressive and effective against WSSV. However, further studies are necessary to elucidate the functions of Rab7 in shrimp cells before applying this methodology at a commercial level.

Evaluation of the relationship between the 14-3-3ε protein and LvRab11 in the shrimp Litopenaeus vannamei during WSSV infection

“…Similar results were reported in PmRab11 and PmRab7. Silencing PmRab11 10 , PmRab7 52 , 53 or LvRab7 54 resulted in inhibition of viral replication in shrimp. For instance, the co-localization between PmRab11 and YHV was observed in hemocytes at 24 to 72 h post viral injection, whereas in PmRab11 knockdown hemocytes, a low level of co-localization of PmRab11 and YHV was detected at the perinuclear region at 24–72 h. These results revealed that PmRab11 is required for YHV infection in shrimp cells 10 .…”

An effective white spot syndrome virus challenge test for cultured shrimp using different biomass of the infected papilla

“…White spot syndrome virus (WSSV) is one of the most virulent pathogens reported for cultured penaeid species [1,2] still causing high mortalities and economical losses [[3], [4], [5]]. Challenge tests are used to evaluate potential control methods for shrimp diseases [[6], [7], [8], [9], [10]], of which, the per os challenge offering infected papilla to susceptible shrimp reproduces one of the pathways of shrimp WSSV infection in farms.…”

Dietary fulvic acid effects on survival and expression of immune-related genes inLitopenaeus vannameichallenged withVibrio parahaemolyticus

“…It is interesting that in L. vannamei, the dietary combination of FA and inulin decreases WSSV prevalence and modulates the expression of immune-related genes associated with protection (Gutiérrez-Dagnino et al, 2015). Regarding the immune system, crustaceans do not have a specific immune memory (Bachère, 2000) and their nonspecific defence system is composed of humoural [prophenoloxidase (proPO) system, haemolymph clotting mechanism, melanization, lysosomal hydrolytic enzymes, antimicrobial peptides, nitric oxide, respiratory burst, opsonization and agglutination mechanisms] and cellular effectors (phagocytosis, encapsulation, cellular degranulation, endocytosis, apoptosis, RNA interference, autophagy and interferon-like system) (Álvarez-Ruiz et al, 2015;Cerenius & Söderhäll, 2004;Jiravanichpaisal, Lee, & Söderhäll, 2006;Lee & Söderhäll, 2002). On this regard, the respiratory burst in hemocytes generates reactive oxygen species (ROS) to kill phagocyted pathogens but can be also harmful for the host.…”