ABSTRACT: A single-tube, non-stop, semi-nested polymerase chain reaction (PCR) technique was developed for simultaneous detection and severity grading of white spot syndrome virus (WSSV) infections in the black tiger shrimp Penaeus monodon. The test uses 1 sense primer and 3 anti-sense primers that produce up to 3 PCR products (1100, 526 and 250 base pairs [bp]) depending upon the severity of infection. Specifically, heavy infections (≥2 × 10⁴ viral particles) of WSSV produce all 3 fragments, while moderate infections (around 2 × 10³ viral particles) produce 2 (526 and 250 bp) and light infections (20 to 200 viral particles) produce 1 (250 bp). In addition, the technique uses internal control primers that yield a shrimp characteristic fragment for non-infected samples and samples with a low quantity of viral target in order to assure integrity and reproducibility of the PCR assays. The non-stop, single-tube, semi-nested PCR technique is simple and convenient and can detect as little as 5 fg WSSV DNA (20 viral particles) in crude extracts of postlarval samples or extracts of pleopods and haemolymph from larger shrimp.

KEY WORDS: White spot syndrome virus · WSSV · Single-tube nested PCR · Penaeus monodon

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Published in DAO Vol. 47, No. 3 (2001) on December 5
Print ISSN: 0177-5103; Online ISSN: 1616-1580. Copyright © Inter-Research, Oldendorf/Luhe, 2001