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An inexpensive and rapid diagnostic method of Koi Herpesvirus (KHV) infection by loop-mediated isothermal amplification.

ABSTRACT: BACKGROUND:Koi Herpesvirus (KHV) affects both juvenile and adult common carp and koi, and is especially lethal to fry. The high mortalities caused by the disease have had a negative impact on the international koi trade. Different diagnostic techniques have been used to detect KHV, including: isolation of the virus in cell culture, electron microscopy, several PCR tests, ELISA and in situ hybridisation. All of these methods are time consuming, laborious and require specialised equipment. RESULTS:A rapid field diagnosis of KHV in common and koi carp was developed using loop-mediated isothermal amplification (LAMP). The LAMP reaction rapidly amplified nucleic acid with high specificity and efficiency under isothermal conditions using a simple water bath. Two methods of extracting DNA from host tissue were compared: extraction by boiling and by using a commercial extraction kit. A set of six primers--two inner primers, two outer primers and two loop primers--was designed from a KHV amplicon. The reaction conditions were optimised for detection of KHV in 60 min at 65 degrees C using Bst (Bacillus stearothermophilus) DNA polymerase. When visualised by gel electrophoresis, the products of the KHV LAMP assay appeared as a ladder pattern, with many bands of different sizes from 50 base-pairs (bp) up to the loading well. The KHV LAMP product could also be simply detected visually by adding SYBR Green I to the reaction tube and observing a colour change from orange to green. All samples positive for KHV by visual detection were confirmed positive by gel electrophoresis. The KHV LAMP had the same sensitivity as a standard PCR assay for the detection of KHV. CONCLUSION:This paper describes an accelerated LAMP assay for diagnosis of KHV. The entire procedure took only 90 minutes to produce a result: 15 minutes for DNA extraction; 60 min for the LAMP reaction; 2 min for visual detection using SYBR Green I. The test can be used under field conditions because the only equipment it requires is a water bath.

SUBMITTER: Soliman H

PROVIDER: S-EPMC1266402 | biostudies-literature | 2005 Oct

REPOSITORIES: biostudies-literature

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An inexpensive and rapid diagnostic method of Koi Herpesvirus (KHV) infection by loop-mediated isothermal amplification.

Soliman Hatem H El-Matbouli Mansour M

Virology journal 20051017

<h4>Background</h4>Koi Herpesvirus (KHV) affects both juvenile and adult common carp and koi, and is especially lethal to fry. The high mortalities caused by the disease have had a negative impact on the international koi trade. Different diagnostic techniques have been used to detect KHV, including: isolation of the virus in cell culture, electron microscopy, several PCR tests, ELISA and in situ hybridisation. All of these methods are time consuming, laborious and require specialised equipment. ...[more]

PMID: 16216123

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Project description:Recently, a novel coronavirus (SARS-CoV-2; coronavirus disease 2019, COVID-19) has emerged, rapidly spreading and severely straining the capacity of the global health community. Many nations are employing combinations of containment and mitigation strategies, where early diagnosis of COVID-19 is vital in controlling illness progression and limiting viral spread within the population. Thus, rapid and accurate methods of early detection are vital to contain COVID-19 and prevent further spread and predicted subsequent infectious waves of viral recurrence in future. Immediately after its initial characterization, Chinese and American Centers for Disease Control and Prevention (CDCs) rapidly employed molecular assays for detection of COVID-19, mostly employing real-time polymerase chain reaction (RT-PCR) methods. However, such methods require specific expensive items of equipment and highly trained analysts, requiring upwards of 4-8 h to process. These requirements coupled with associated financial pressures may prevent effective deployment of such diagnostic tests. Loop mediated isothermal amplification(LAMP) is method of nucleic acid amplification which exhibits increased sensitivity and specificity are significantly rapid, and do not require expensive reagents or instruments, which aids in cost reduction for coronavirus detection. Studies have shown the successful application of LAMP assays in various forms to detect coronavirus RNA in patient samples, demonstrating that 1-10 copies of viral RNA template per reaction are sufficient for successful detection, ~100-fold more sensitive than conventional RT-PCR methods. Importantly, studies have also now demonstrated the effectiveness of LAMP methodology in the detection of SARS-CoV-2 RNA at significantly low levels, particularly following numerous improvements to LAMP assay protocols. We hypothesise that recent advancements in enhanced LAMP protocols assay perhaps represent the best chance for a rapid and robust assay for field diagnosis of COVID-19, without the requirement of specialized equipment and highly trained professionals to interpret results. Herein, we present our arguments with a view to disseminate such findings, to assist the combat of this virus that is proving so devastating. We hope that this strategy could be applied rapidly, and confirmed for viability with clinical samples, before being rolled out for mass-diagnostic testing in these current times.

Project description:Bacillus Calmette-Guérin (BCG) is widely used as a live attenuated vaccine against Mycobacterium tuberculosis and is an agent for standard prophylaxis against the recurrence of bladder cancer. Unfortunately, it can cause severe infectious diseases, especially in immunocompromised patients, and the ability to immediately distinguish BCG from other M. tuberculosis complexes is therefore important. In this study, we developed a simple and easy-to-perform identification procedure using loop-mediated amplification (LAMP) to detect deletions within the region of difference, which is deleted specifically in all M. bovis BCG strains. Reactions were performed at 64 °C for 30 min and successful targeted gene amplifications were detected by real-time turbidity using a turbidimeter and visual inspection of color change. The assay had an equivalent detection limit of 1.0 pg of genomic DNA using a turbidimeter whereas it was 10 pg with visual inspection, and it showed specificity against 49 strains of 44 pathogens, including M. tuberculosis complex. The expected LAMP products were confirmed through identical melting curves in real-time LAMP procedures. We employed the Procedure for Ultra Rapid Extraction (PURE) kit to isolate mycobacterial DNA and found that the highest sensitivity limit with a minimum total cell count of mycobacterium (including DNA purification with PURE) was up to 1 × 10(3) cells/reaction, based on color changes under natural light with FDA reagents. The detection limit of this procedure when applied to artificial serum, urine, cerebrospinal fluid, and bronchoalveolar lavage fluid samples was also about 1 × 10(3) cells/reaction. Therefore, this substitute method using conventional culture or clinical specimens followed by LAMP combined with PURE could be a powerful tool to enable the rapid identification of M. bovis BCG as point-of-care testing. It is suitable for practical use not only in resource-limited situations, but also in any clinical situation involving immunocompromised patients because of its convenience, rapidity, and cost effectiveness.

Dataset Information

An inexpensive and rapid diagnostic method of Koi Herpesvirus (KHV) infection by loop-mediated isothermal amplification.

Publications

An inexpensive and rapid diagnostic method of Koi Herpesvirus (KHV) infection by loop-mediated isothermal amplification.

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