Application of a Label-Free Immunosensor for White Spot Syndrome Virus (WSSV) in Shrimp Cultivation Water.

White spot syndrome virus (WSSV) is a major pathogen affecting the shrimp industry worldwide. In a preliminary study, WSSV binding protein (WBP) was specifically bound to the VP26 protein of WSSV. Therefore, we have developed the label-free affinity immunosensor using the WBP together with anti-GST-VP26 for quantitative detection of WSSV in shrimp pond water. When the biological molecules were immobilized on a gold electrode to form a self-assembled monolayer, it was then used to detect WSSV using a flow injection system with optimized conditions. Binding between the different copies of WSSV and the immobilized biological molecules was detected by an impedance change (ΔZ″) in real time. The sensitivity of the developed immunosensor was in the linear range of 1.6 × 10(1)-1.6 × 10(6) copies/µl. The system was highly sensitive for the analysis of WSSV as shown by the lack of impedance change when using yellow head virus (YHV). The developed immunosensor could be reused up to 37 times (relative standard deviation (RSD), 3.24 %) with a good reproducibility of residual activity (80-110 %). The immunosensor was simple to operate, reliable, reproducible, and could be applied for the detection and quantification of WSSV in water during shrimp cultivation.

Development of an immuno-based colorimetric assay for white spot syndrome virus.

White spot syndrome virus (WSSV) is a major cause of infectious disease in cultured shrimp. A fast and reliable method for detecting and monitoring the amount of WSSV during farming would be extremely useful. This work describes a sandwich immunoassay that uses anti-GST-VP26, a WSSV-binding protein (WBP), and modified streptavidin magnesphere paramagnetic particles (SMPPs) to develop the technique. The WBP was immobilized on SMPPs and later bound to different copies of WSSV. The binding was detected using anti-GST-VP26 conjugated to alkaline phosphatase. This enzymatic reaction successfully changed the test solution to a concentration-dependent yellow color that was measured at 405 nm. The sensitivity of this method was between 1.6 × 10(4) and 1.6 × 10(7) copies µL(-1) of WSSV. In this study, the color for detection and semiquantitative analysis is easily observed and measured and can lead to the development of a test kit for screening WSSV during shrimp farming.

Validity evaluation of in-house preparation kit, vaginal pH paper test combined amine tube test, for the simple diagnosis of bacterial vaginosis.

OBJECTIVE: Determine the positive in-house preparation kit for suggested bacterial vaginosis (BV) for both elevated vaginal pH > 4.5 and positive amine test, as well as evaluate for validity of sensitivity, specificity, positive predictive value, and negative predictive value against Chandeying criteria for confirmed BV. MATERIAL AND METHOD: A cross-sectional study among the women who presented with an abnormal vaginal discharge (AVD) or asymptomatic annual cervical cytology screening was done. Each vaginal discharge was divided into two parts of investigation. The first part included the clinical criteria of confirmed BV, based on at least three out of five indicators, the vaginal pH > 4.5, homogeneous and thin discharge (milky discharge), positive sniff/amine test, clue cell > 20% of total vaginal epithelial cells, and scanty or absence lactobacilli. The second part included the in-house preparation kit of suggestive BV relied on elevated vaginal pH > 4.5 and positive amine tube test. RESULTS: Twenty-six women were enrolled. Of the complaint of AVD/asymptomatic had 2/10 of confirmed BV (12 cases), and 1/13 of confirmed non-BV (14 cases). The in-house preparation kit, compared with the clinical criteria, had sensitivity of 91%, specificity of 71%, positive predictive value of 73%, and negative predictive value of 90%. There were false negative of 1/12 cases (8.3%), and false positive of 4/14 cases (28.5%). CONCLUSION: The in-house preparation kit favorably compared with the clinical criteria and has the advantage of being simple, rapid, and easily performed in resource poor setting. Further development on sensitivity and specificity of the test is suggested.