Environmental DNA (eDNA) could be applied in monitoring waterborne viruses of aquatic animals. However, there are few data for practical application of eDNA in fish farms for the control of disease outbreaks.

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Reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed for detecting the structural glycoprotein gene of yellow head virus (YHV). The RT-LAMP assay is a novel method of gene amplification that amplifies nucleic acid with high specificity, sensitivity and rapidity under isothermal conditions with a set of four specially designed primers that recognize six distinct sequences of the target. The whole procedure is very simple and rapid, and reaction time and temperatures were optimized for 60 min at 65 degrees C, respectively. Detection of gene amplification could be accomplished by agarose gel electrophoresis. The standardized RT-LAMP procedure was used to detect YHV in the heart and gill from infected shrimp. Thus, the RT-LAMP assay is extremely rapid, cost-effective, sensitive and specific and has potential usefulness for rapid diagnosis for YHV detection in shrimp.

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Carp edema virus disease (CEVD), or koi sleepy disease, is caused by CEV. Here, we report the complete genome sequence of CEV strain FTI2020, isolated from koi carp. This sequence information has great potential for improving our understanding of the genetic characteristics of this piscine poxvirus.

Repeatedly the shrimp culturing industry faces serious economic loss due to white spot disease caused by white spot syndrome virus (WSSV) in penaeid shrimp. The present study was carried out to determine the antiviral activity of traditional Indian medicinal herb Phyllanthus amarus against WSSV in freshwater crab, Paratelphusa hydrodomous (Herbst). For experimental challenge, crabs were injected with three different solvent extracts of P. amarus (aqueous, acetone and petroleum ether) along with WSSV. The efficacy of the extracts was confirmed by bioassay, histopathology and reverse transcriptasepolymerase chain reaction (RT-PCR). The overall results of the present study confirmed that acetone and petroleum ether extracts of P. amarus have significant antiviral effect against WSSV.

Aims:  White spot syndrome virus (WSSV) continues to be the most pathogenic virus among the crustacean aquaculture causing mass mortality. In the present study, we established a one‐step, single tube, real‐time accelerated loop‐mediated isothermal amplification (real‐time LAMP) for quantitative detection of WSSV. Materials and Methods:  A set of six specially designed primers that recognize eight distinct sequences of the target. The whole process can be completed in 1 h under isothermal conditions at 63°C. Detection and quantification can be achieved by real‐time monitoring in an inexpensive turbidimeter based on threshold time required for turbidity in the LAMP reaction. A standard curve was constructed by plotting viral titre against the threshold time (Tt) using plasmid standards with high correlation coefficient (R2 = 0·988). Conclusions:  Sensitivity analysis using 10‐fold dilutions (equivalent to 35 ng μl−1 to 35 ag μl−1) of plasmid standards revealed this method is capable of detecting upto 100 copies of template DNA. Cross‐reactivity analysis with DNA/cDNA of IHHNV, TSV, YHV‐infected and healthy shrimp showed this method is highly specific for quantitative detection of WSSV. Significance and Impact of the Study:  WSSV real‐time LAMP assay appears to be precise, accurate and a valuable tool for the detection and quantification of WSSV in large field samples and epidemiological studies.