Species-specific loop-mediated isothermal amplification (LAMP) assay for identification of tissue of cattle origin by targeting mitochondrial gene sequences

Recent advancements with loop-mediated isothermal amplification (LAMP) in assessment of the species authenticity with meat and seafood products

Species adulteration or mislabeling with meat and seafood products could negatively affect the fair trade, wildlife conservation, food safety, religion aspect, and even the public health. While PCR-based methods remain the gold standard for assessment of the species authenticity, there is an urgent need for alternative testing platforms that are rapid, accurate, simple, and portable. Owing to its ease of use, low cost, and rapidity, LAMP is becoming increasingly used method in food analysis for detecting species adulteration or mislabeling. In this review, we outline how the features of LAMP have been leveraged for species authentication test with meat and seafood products. Meanwhile, as the trend of LAMP detection is simple, rapid and instrument-free, it is of great necessity to carry out end-point visual detection, and the principles of various end-point colorimetry methods are also reviewed. Moreover, with the aim to enhance the LAMP reaction, different strategies are summarized to either suppress the nonspecific amplification, or to avoid the results of nonspecific amplification. Finally, microfluidic chip is a promising point-of-care method, which has been the subject of a great deal of research directed toward the development of microfluidic platforms-based LAMP systems for the species authenticity with meat and seafood products.

Visual Detection of Chicken Adulteration Based on a Lateral Flow Strip-PCR Strategy

The aim of this study was to develop an accurate, easy-to-use, and cost-effective method for the detection of chicken adulteration based on polymerase chain reaction (PCR) and lateral flow strip (LFS). We compared six DNA extraction methods, namely the cetyltrimethylammonium bromide (CTAB) method, salt method, urea method, SDS method, guanidine isothiocyanate method, and commercial kit method. The chicken cytb gene was used as a target to design specific primers. The specificity and sensitivity of the PCR-LFS system were tested using a self-assembled lateral flow measurement sensor. The results showed that the DNA concentration obtained by salt methods is up to 533 ± 84 ng µL⁻¹, is a suitable replacement for commercial kits. The PCR-LFS method exhibits high specificity at an annealing temperature of 62 °C and does not cross-react with other animal sources. This strategy is also highly sensitive, being able to detect 0.1% of chicken in artificial adulterated meat. The results of the test strips can be observed with the naked eye within 5 min, and this result is consistent with the electrophoresis result, demonstrating its high accuracy. Moreover, the detection system has already been successfully used to detect chicken in commercial samples. Hence, this PCR-LFS strategy provides a potential tool to verify the authenticity of chicken.

Loop-Mediated Isothermal Amplification (LAMP): The Better Sibling of PCR?

In 1998, when the PCR technique was already popular, a Japanese company called Eiken Chemical Co., Ltd. designed a method known as the loop-mediated isothermal amplification of DNA (LAMP). The method can produce up to 109 copies of the amplified DNA within less than an hour. It is also highly specific due to the use of two to three pairs of primers (internal, external, and loop), which recognise up to eight specific locations on the DNA or RNA targets. Furthermore, the Bst DNA polymerase most used in LAMP shows a high strand displacement activity, which eliminates the DNA denaturation stage. One of the most significant advantages of LAMP is that it can be conducted at a stable temperature, for instance, in a dry block heater or an incubator. The products of LAMP can be detected much faster than in standard techniques, sometimes only requiring analysis with the naked eye. The following overview highlights the usefulness of LAMP and its effectiveness in various fields; it also considers the superiority of LAMP over PCR and presents RT-LAMP as a rapid diagnostic tool for SARS-CoV-2.

A cost-effective plan for global testing - an infection rate stratified, algorithm guided, multiple-level, continuously pooled testing strategy

The most effective measure to prevent or stop the spread of infectious diseases is the early identification and isolation of infected individuals through comprehensive screening. At present, in the COVID-19 pandemic, such screening is often limited to isolated regions as determined by local governments. Screening of potentially infectious individuals should be conducted through coordinated national or global unified actions. Our current research focuses on using resources to conduct comprehensive national and regional regular testing with a risk rate based, algorithmic guided, multiple-level, pooled testing strategy. Here, combining methodologies with mathematical logistic models, we present an analytic procedure of an overall plan for coordinating state, national, or global testing. The proposed plan includes three parts 1) organization, resource allocation, and distribution; 2) screening based on different risk levels and business types; and 3) algorithm guided, multiple level, continuously screening the entire population in a region. This strategy will overcome the false positive and negative results in the polymerase chain reaction (PCR) test and missing samples during initial tests. Based on our proposed protocol, the population screening of 300,000,000 in the US can be done weekly with between 15,000,000 and 6,000,000 test kits. The strategy can be used for population screening for current COVID-19 and any future severe infectious disease when drugs or vaccines are not available.

Recombinase Polymerase Amplification Based Multiplex Lateral Flow Dipstick for Fast Identification of Duck Ingredient in Adulterated Beef

Simple Summary

The adulteration and authenticity of meat and meat products has become a global social problem. Beef is often intentionally adulterated with cheap meat. In order to ensure the authenticity of meat, and provide technical support to regulatory authorities, we developed a rapid and visual method to detect duck ingredient in adulterated beef. This method is implemented recombinase polymerase amplification (RPA) and multiplex lateral flow dipstick (MLFD) cascade. The whole RPA-MLFD reaction process can be finished within 35 min, and the results can be determined by naked eyes. RPA-MLFD was applied to simultaneously detect duck ingredient and beef ingredient without using additional instruments. An adulteration ratio as low as 5% of duck ingredient in beef can be easily measured. Moreover, we confirmed that our new method held good potential in the detection of commercially processed meat samples. Therefore, this study reports a useful animal derived meat adulteration detection method, which have potential application in future.

Abstract

Meat adulteration has become a global social problem. In order to protect consumers from meat adulteration, several methods have been developed to identify meat species. However, the conventional methods are labor-intensive, time-consuming and require instruments. In the present study, a rapid and visual method based on recombinase polymerase amplification (RPA) and multiplex lateral flow dipstick (MLFD) was developed to detect duck ingredient in adulterated beef. Using recombinase and strand displacement polymerase enable RPA to amplify different double-labeled DNA amplicons at room temperature, which can be further detected by MLFD. The whole reaction process can be finished within 35 min, and the results can be determined by naked eyes. As low as 5% of duck ingredient in adulterated beef can be easily measured. Moreover, we confirmed that our new method held good potential in the detection of commercially processed meat samples. In conclusion, this study reported a useful animal derived meat adulteration detection method, which have potential application in future.

Identification of Chicken-Derived Ingredients as Adulterants Using Loop-Mediated Isothermal Amplification

ABSTRACT

Meat adulteration has recently become an issue of increasing public concern. In addition to posing a health risk to consumers with metabolic disorders or allergies, meat adulteration has triggered many economic and religious problems. Chicken meat is a common adulterant in nonchicken products because of its low cost and ready availability. A loop-mediated isothermal amplification assay coupled with a lateral flow dipstick was developed to identify chicken in nonchicken products. We optimized the amplification time and temperature to obtain the best result. This assay is performed at a constant temperature in a water bath and can be completed in 1 h. No precision instruments or equipment are needed. With a one-step reaction and easy operation, the testing cost is low. This method is highly sensitive and specific and is a valuable method for identifying chicken in nonchicken products to meets the requirements of on-site inspection and detection.

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