Development of a loop-mediated isothermal amplification assay for the detection and quantification of epizootic epitheliotropic disease virus (salmonid herpesvirus-3)

Abstract

Epizootic Epitheliotropic Disease Virus (EEDV; Salmonid Herpesvirus-3) causes a serious disease hatchery-reared lake trout (Salvelinus namaycush), threatening restoration efforts of this species in North America. The current inability to replicate EEDV in vitro necessitates the search for a reproducible, sensitive, and specific assay that allows for its detection and quantitation in a time-and cost-effective manner. Herein, we describe a loopmediated isothermal amplification (LAMP) assay that was developed for the quantitative detection of EEDV in infected fish tissues. The newly developed LAMP reaction was optimized in the presence of calcein, and the best results were produced using 2 mM MgCl 2 , 1.8 mM dNTPs and at an incubation temperature of 67.1°C. This method was highly specific to EEDV, as it showed no cross-reactivity with several fish viruses, including Salmonid Herpesvirus -1 , -2, -4, and -5, Infectious Pancreatic Necrosis Virus, Spring Viremia of Carp Virus, Infectious Hematopoietic Necrosis Virus, Golden Shiner Reovirus, Fathead Minnow Nidovirus, and Viral Hemorrhagic Septicemia Virus. The analytical sensitivity of the EEDV-LAMP method was estimated to be as low as 16 copies of plasmid per reaction. When infected fish tissue was used, a positive reaction could be obtained when an infected gill tissue sample that contained 430 viral copies/μg was diluted up to five orders of magnitude. The sensitivity and specificity of the newly developed LAMP assay compared to the SYBR Green qPCR assay were 84.3% and 93.3%, respectively. The quantitative LAMP for EEDV had a correlation coefficient (R 2 = 0.980), and did not differ significantly from the SYBR Green quantitative PCR assay (p > 0.05). Given its cost-and time-effectiveness, this quantitative LAMP assay is suitable for screening lake trout populations and for the initial diagnosis of clinical cases.

Rapid cyprinid herpesvirus 3 detection using loop-mediated isothermal amplification (LAMP) combined with gold nanoprobes and SYBR safe

“…Several molecular diagnostic tests have been adopted based on nucleic acid ampli cation methods for direct identi cation of CyHV-3 (Bercovier et , it has become the chosen technique for amplifying nucleic acids present at highly low quantities in biological specimens as a replacement for the conventional detecting methods, due to its distinguished advantages. However, achieving e cient nucleic acid analysis depends not only on the performance of ampli cation methods but also on the selected methods to monitor the reaction (Zhang et al 2019).…”

“…precipitate, uorescence, and colorimetric indicators) or direct detection of its amplicons (e.g. DNA intercalating dye, lateral ow dipstick, and nanoparticle) (Zhang et al 2019). However, some drawbacks including false negative results, inhibition of ampli cation, cross-contamination, and ambiguous reading interpretations are reported (Goto et al 2009;Chen et al 2018).…”

Rapid Cyprinid herpesvirus 3 detection using loop-mediated isothermal amplification (LAMP) combined with gold nanoprobes and SYBR safe

“…After introducing the LAMP method in 2000, it has become the chosen technique for amplifying nucleic acids present at highly low quantities in biological specimens as a replacement for the conventional detecting methods, due to its distinguished advantages. However, achieving e cient nucleic acid analysis depends not only on the performance of ampli cation methods but also on the selected methods to monitor the reaction (Zhang et al 2019).…”

Development of Quantitative Real-time PCR and Loop-mediated Isothermal Amplification (LAMP) Assays for Detection of <i>Microsporidium seriolae</i>

“…The plot of Tt value in LAMP fits to the power approximation and obtained a high coefficient of determination in the range of 10 2 to 10 8 copies. The LAMP method shows relatively high quantification with the highly purified plasmid DNA as a template (Zhang et al, 2019).…”