Examination of Taura Syndrome Virus (TSV) in white shrimp (Litopenaeus vannamei) and tiger prawn (Penaeus monodon) with Polymerase Chain Reaction (PCR) method

Abstract

Frozen shrimp is one type of fishery product. Fishery products are a type of food that is susceptible to damage due to pathogenic microbial contamination. Virus is a type of pathogen that can attack fishery commodities including shrimp. One type of virus that attacts shrimp namely Taura Syndrome Virus (TSV). This study aims to detect Taura Syndrome Virus in frozen white shrimp (Litopenaeus vannamei) and tiger prawn (Penaeus monodon) products. The research was carried out in December 2019 - January 2020 at the Fish Quarantine Center, Quality Control and Safety of Fishery Products in Surabaya II. Materials used in this study consist of two types of frozen shrimp, namely 5 samples of tiger prawn and 2 samples of white shrimp. Virus testing samples were detected molecularly using the conventional Polymerase Chain Reaction (PCR) method which consisted of an extraction stage using a Silica Extraction Kit, an amplification stage, electrophoresis and result visualization. This research was observative, then the data obtained were analyzed descriptively. The results showed that all shrimp samples consisting of white shrimp dan tiger prawn were negative of the Taura Syndrome Virus (TSV).

Viral Shrimp Diseases Listed by the OIE: A Review

“…TSV is a positive-sense, icosahedral-shaped, non-enveloped single-stranded RNA genome of 10.2 kb with a diameter of 32 nm [ 129 ] ( Table 1 ). TSV is taxonomically classified in the Aparavirus genus belonging to the Dicistroviridae family [ 117 ].…”

“…TSV infection in P. vannamei is divided into three stages: acute (7 days after infection with an asymptomatic phase of 2–5 days), transition (lasting 5 days after the acute stage), and chronic (survivors after molting) stages, with a mortality rate of 60–90% [ 86 , 133 ]. Clinical symptoms of acute TSV infection in farmed P. vannamei are characterized by a reddish body color (especially on the tail; uropods, and appendages induced by chromatophore expansion) and irregular black (melanization) spots under the cuticle layer, in addition to anorexia, an erratic swimming behavior, lethargy, soft cuticles, anorexia, flaccid bodies and opaque musculature [ 95 , 129 ] ( Figure 19 ). Shrimp acutely infected with TSV persist for 1–10 days after infection, and exhibit TSV-specific histological lesions, and mortality occurs during or immediately after molting [ 134 , 135 ].…”

“…The TSV chronic infection stage (or ‘recovery stage’) appears from 6 days after TSV infection and lasts for a period of 8–12 months in experimentally infected P. vannamei with no disease symptoms, normal swimming behavior, and feeding, and no mortality [ 95 ]. During chronic TSV infection, there can be complete removal of TSV through apoptosis or there can be continued infection in a chronic state due to continuous virus replication, which is determined by the host’s immunity, nutritional status, and overall health condition [ 129 ]. In the chronic stage of TSV infection, shrimp are asymptomatic, and the only histologically identifiable lesions are numerous lymphoid organ spheroids (LOS) [ 133 ].…”

“…TSV infection at acute, transition, and early chronic stages can be accurately diagnosed using histological or molecular methods, but it is difficult to detect low virus levels during the chronic stage, when the symptoms and most histological lesions disappear [ 86 ]. TSV virus testing is carried out using PCR assays, such as a commercial nested RT-PCR kits and reverse transcriptase PCR (RT-PCR) using TSV virus target organs such as uropods, gills, body cuticles, and swimming feet; the OIE recommends using a one-step PCR method for TSV testing [ 129 , 139 ] ( Table 5 ).…”