Antisense RNA mediated protection from white spot syndrome virus (WSSV) infection in Pacific white shrimp Litopenaeus vannamei

Antisense (AS) plasmid constructs were used to target genes VP28, VP39 and wsv477 of white spot syndrome virus (WSSV) in the Pacific white shrimp Litopenaeus vannamei, and subsequent protection from the virus was investigated. PCR amplified products of the targeted viral ORFs were cloned downstream in antisense orientation (3'–5') into a plasmid vector having elongation factor 1α (EF1α) promoter. Shrimp were injected with the AS plasmids intramuscularly followed by a challenge with WSSV. The AS plasmids administered individually (pEF-VP28, pEF-VP39 and pEF-wsv477) and in combinations (pEF-VP28 + VP39, pEF-VP28 + wsv477, pEF-VP39 + wsv477) provided significant protection to the L. vannamei against WSSV. Mortality began in the positive and promoter control groups on day three of viral challenge and reached 100% by day nine. The shrimp injected with AS plasmid of VP28, VP39 and wsv477 showed survival rate of 50%, 60% and 90% respectively, in comparison with the control groups at 9 days post infection (dpi). The AS constructs targeting the early regulatory gene wsv477 produced statistically superior protection against WSSV, both alone and in combination as pEF-VP28 + wsv477 and pEF-VP39 + wsv477