Efficacy of double-stranded RNA against white spot syndrome virus (WSSV) non-structural (orf89, wsv191) and structural (vp28, vp26) genes in the Pacific white shrimp Litopenaeus vannamei

Abstract

White spot syndrome virus (WSSV) is a major pathogen in shrimp aquaculture. RNA interference (RNAi) is a promising tool against viral infections. Previous works with RNAi showed different antiviral efficacies depending on the silenced gene. This work evaluated the antiviral efficacy of double-stranded (ds) RNA against two non-structural (orf89, wsv191) WSSV genes compared to structural (vp26, vp28) genes to inhibit an experimental WSSV infection. Gene orf89 encodes a putative regulatory protein and gene white spot virus (wsv)191 encodes a nonspecific nuclease; whereas genes vp26 and vp28 encode envelope proteins, respectively. Molecules of dsRNA against each of the WSSV genes were intramuscularly injected (4 lg per shrimp) into a group of shrimp 48 h before a WSSV challenge. The highest antiviral activity occurred with dsRNA against orf89, vp28 and vp26 (cumulative mortalities 10%, 10% and 21%, respectively). In contrast, the least effective treatment was wsv191 dsRNA (cumulative mortality 83%). All dead animals were WSSV-positive by one-step PCR, whereas reverse-transcription PCR of all surviving shrimp confirmed inhibition of virus replication. This study showed that dsRNA against WSSV genes

Digestibilidad in vitro del dsRNA específico por enzimas del tracto digestivo del camarón Litopenaeus vannamei

“…The results indicated different antiviral responses against WSSV. The whiteleg shrimp L. vannamei treated with dsRNA-ORF89 and dsRNA-vp28 achieved a 90% survival while the shrimp treated with dsRNA-vp26 and dsRNAwsv191 achieved a survival of 79 and 17% relative to the positive control WSSV (0%) (6), which supports the theory that the antiviral effect depends on the gene to which the block is directed (7), making dsRNA-ORF89 an excellent candidate to incorporate in shrimp feed as an antiviral additive.…”

“…It will depend on food digestion time with the dsRNA in the digestive tract of the shrimp which, depends on the species, size, and other factors, such as temperature (21) for example, in whiteleg shrimp, digestion, and elimination lasts ~3 hours in juveniles (and even less in smaller shrimp) (32). The amount of dsRNA-ORF89 in feed and the quantity of ingested feed will be important factors for success in a WSSV treatment (6). The amount of specific dsRNA recommended for the antiviral effect to take effect from the feed should be 5-10 times greater than that injected (11,15,33).…”

“…Los resultados indican diferentes respuestas antivirales contra WSSV. Los camarones patiblancos tratados con dsRNA-ORF89 y dsRNA-vp28 lograron una supervivencia del 90%, mientras que, los camarones tratados con dsRNA-vp26 dsRNA-wsv191 lograron una supervivencia del 79 y 17 % respecto al control positivo a WSSV (0%) (6). Lo que apoya la teoría de que el efecto antiviral depende del gen al que se dirige el bloqueo (7).…”

Production of specific dsRNA against white spot syndrome virus in the yeastYarrowia lipolytica

“…The viral inoculum was prepared by infecting the shrimp prior to start of the experiment as described by Escobedo‐Bonilla et al. (). Dying shrimp tissues were weighed and homogenized in 10 volumes (W/V) of 2× phosphate buffered saline (PBS 2×), centrifuged at 3,000 g for 20 min at 4°C and the supernatant filtered (0.45 μm).…”

“…In addition, Y. lipolytica and other yeasts have been used as immunostimulants for aquatic organisms enhancing the immune response against pathogenic bacteria and viruses (Caruffo et al., ; Chang, Chen, Su & Lio, ; Chang, Su, Chen & Lio, ; Chang et al., ; Robertson & Kuenen, ). Finally, we have chosen the WSSV ORF89 gene which recently has been reported to be efficient in inducing antiviral activity by application of specific dsRNA by intramuscular injection in the Litopenaeus vannamei shrimp (Escobedo‐Bonilla, Vega & Mejía‐Ruiz, ).…”