Highly sensitive capacitive biosensor for detecting white spot syndrome virus in shrimp pond water

Water is one major pathways by which the white spot syndrome virus (WSSV) pathogen enters aquaculture facilities. This paper describes the production and use of a capacitive biosensor for the quantitative detection of as little as 1 copy/μl of WSSV in shrimp pond water. A glutathione-S-transferase tag for white spot binding protein (GST-WBP) was immobilized on a gold electrode through a self-assembled monolayer. Binding between WSSV and the immobilized GST-WBP was directly detected by a capacitance measurement. Under optimum conditions, the capacitive biosensor detected WSSV over a wide linear range of between 1 and 1 × 105 copies/μl. The system was highly selective for WSSV. One analysis cycle required only 20–25 min of analysis time and 25 min of regeneration time. The capacitive biosensor was applied to analyze WSSV concentration in eight shrimp pond water samples and the results were in good agreement with those obtained by a real time quantitative polymerase chain reaction (real-time PCR) method (P > 0.05). The immobilized GST-WBP provided and could be reused for up to 39 analysis cycles for one electrode preparation with a relative standard deviation (RSD) of 2.4% and a good reproducibility of residual activity (95.8 ± 2.3%). The appealing performance of this biosensor indicated that it had great potential for an accurate very sensitive, quantitative, detection method for WSSV.