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Largemouth bass ranavirus (LMBRaV), also known as largemouth bass virus (LMBV), is a high mortality pathogen in largemouth bass. A rapid, sensitive, specific and convenient diagnosis method is an urgent requirement for the prevention of virus transmission. In the present study, a droplet digital PCR (ddPCR) method based on the major capsid protein (mcp) gene was established to detect and quantify the virus genome copy number. Oligonucleotide primers were designed based on the LMBRaV mcp gene sequence. The specificity and sensitivity of ddPCR assay were analysed. The other aquatic virus including Chinese giant salamander iridovirus (GSIV), Cyprinid herpesvirus II (CyHV‐2) and infectious spleen and kidney necrosis virus could not be detected by LMBRaV ddPCR assay. The detection limit of ddPCR assay was 2 ± 0.37 copies/μl DNA sample. And this ddPCR assay had great repeatability and reproducibility. In clinical diagnosis of 50 largemouth bass, 43 positive samples were detected by ddPCR, whereas only 34 positive samples were detected by quantitative PCR (qPCR). This LMBRaV detection assay provided a specific and sensitive method for the rapid diagnosis of LMBRaV infection in largemouth bass as well as quantification of the virus load. [ABSTRACT FROM AUTHOR]

Sulfhydryl compounds are regarded as potential functional monomers for arsenious acid imprinted polymers due to their high affinity to arsenious acid in aqueous solution. However, the recognition and binding mechanisms between arsenious acid and sulfhydryl compounds in solutions remain unclear. In this work, the binding interactions between arsenious acid and dithiothreitol (DTT)/dithioerythritol (DTE) in aqueous solution and HEPES buffer at different pH values were investigated using density functional theory (DFT) calculations. DTE binding complexes were calculated to be more energetically favorable than DTT. H3AsO3–DTE−–H2O and H3AsO3–DTE–HEPES− complexes were shown to have the greatest affinity with the occurrence of deprotonation as pH changes. This indicates that the optimal pH ranges of binding between the template and monomer (DTT/DTE) in aqueous solution and HEPES buffer are 8.30–9.23 and 7.50–8.30, respectively. The reduced density gradient (RDG) method and non-covalent interaction (NCI) analysis demonstrated the presence of hydrogen bonds, van der Waals forces and repulsive forces in the systems. Energy decomposition analysis (EDA) predicted that the electrostatic force is the dominant composition of binding energy. The non-covalent properties of hydrogen bonds were further explained by the quantum theory of atoms in molecules (QTAIM) analysis. The calculated infrared (IR) spectrum reflected the formation of hydrogen bonds, which agreed well with the experimental IR spectrum. The change rate of the absorbance in ultraviolet-visible spectroscopy (UV-Vis) provided information for the best binding of H3AsO3–DTE in HEPES solution. [ABSTRACT FROM AUTHOR]