Closed-tube field-deployable loop-mediated isothermal amplification (LAMP) assay based on spore wall protein (SWP) for the visual detection of Enterocytozoon hepatopenaei (EHP)

Programmable and ultra-efficient Argonaute protein-mediated nucleic acid tests: A review

With the attributes of high sensitivity, single-base resolution, multiplex detection capability, and programmability upon nucleic acid recognition, Argonaute (Ago)-based biosensing assays are increasingly recognized as one of the most promising tools for precise identification and quantification of target analytes. Employed as highly specific sequence recognition elements of these robust diagnostic methods, Agos are revolutionizing how nucleic acid targets are detected. A systematic and comprehensive summary of this emerging and rapid-advancing technology is necessary to give play to the potential of Ago-based biosensing assays. The structure and function of Agos were briefly overviewed at the beginning of the work, followed by a review of the recent advancements in employing Agos sensing for detecting various targets with a comprehensive analysis such as viruses, tumor biomarkers, pathogens, mycoplasma, and parasite. The significance and benefits of these platforms were then deliberated. In addition, the authors shared subjective viewpoints on the existing challenges and offered relevant guidance for the future progress of Agos assays. Finally, the future research outlook regarding Ago-based sensing in this field was also outlined. As such, this review is expected to offer valuable information and fresh perspectives for a broader group of researchers.

Enterocytozoon hepatopenaei Infection in Shrimp: Diagnosis, Interventions, and Food Safety Guidelines

The emergence of disease in shrimp has governed much concern in food safety and security among consumers with the recent reports on hepatopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP). The microsporidians present in shrimp remain a silent pathogen that prevents optimal shrimp growth. However, the biggest threat is in its food safety concerns, which is the primary focus in ensuring food biosecurity and biosafety. Hence, the objective of this review is to summarise the current knowledge of EHP and its infection in shrimp with food safety concerns. This paper provides an analysis of the diagnostic methods for detecting EHP infections in shrimp aquaculture. Interventions with current molecular biology and biotechnology would be the second approach to addressing EHP diseases. Finally, a systematic guideline for shrimp food safety using diagnostic and intervention is proposed. Thus, this review was aimed to shed light on effective methods for the diagnosis and prevention of EHP infection in shrimp. We also include information on molecular and genomics tools as well as innate immune biomolecules as future targets in the intervention strategies on the microsporidsosis life cycle in shrimp and its environment. Overall, this will result in reduced disease outbreaks in shrimp aquaculture, ensuring the shrimp food safety in the future.

An isothermal enzymatic recombinase amplification (ERA) assay for rapid and accurate detection of Enterocytozoon hepatopenaei infection in shrimp

Enterocytozoon hepatopenaei (EHP) is a kind of microsporidian parasite belonging to fungi, and poses a serious threat to prawn farmers. Due to the lack of effective treatments for EHP, the establishment of a rapid and sensitive detection method would be beneficial to the control and prevention of this prawn parasitic disease. In this study, an isothermal enzymatic recombinase amplification (EHP-ERA) assay that could diagnose EHP within 20 min at 42 °C was developed and evaluated. The determined final concentrations of primers and probe in the reaction system were 400 nM and 120 nM, respectively. EHP-ERA was carried out within 13 min (24.31 ± 0.37 Ct) with a detection limit of 10 copies/μL. The results of specificity test showed that EHP-ERA had no cross-reactivity with white spot syndrome virus (WSSV), Vibrio parahaemolyticus strain causing acute hepatopancreatic necrosis disease (VpAHPND), and infectious hypodermal and hematopoietic necrosis virus (IHHNV) and specific pathogen free (SPF) shrimp. Using 32 clinical samples, the practical diagnostic results of EHP-ERA was consistent with nested PCR and real-time PCR (qPCR) under the premise of less time-consuming and simpler operation. In summary, we established a simple, rapid, and effective ERA assay for the detection of EHP, which had great potential to be widely used in both lab and practical usage.

Pyrococcus furiosus Argonaute Combined with Recombinase Polymerase Amplification for Rapid and Sensitive Detection of Enterocytozoon hepatopenaei

Enterocytozoon hepatopenaei (EHP) is one of the most serious pathogens in shrimp farming. This study combines recombinase polymerase amplification (RPA) with the Argonaute from Pyrococcus furiosus (PfAgo) and establishes a sensitive and reliable method for on-site detection of EHP. With careful screening of gDNA and optimization of the reaction, the method shows a good specificity and reaches a sensitivity of single copy per reaction, which is higher than the sensitivity of the currently available molecular assays. The whole procedure can be finished within 1.5 h including the sample processing time and only requires minimum laboratory support, which is user-friendly for on-site environments. This is the first application of PfAgo for the diagnosis of infectious diseases in seafood supply chains. It provides a reliable method for on-site detection of EHP in shrimp farms and establishes a groundwork for multiplex detection of important pathogens in seafood farming using PfAgo.

Detection of Brucella S2 vaccine strain by a loop-mediated isothermal amplification (LAMP) method

Introduction

Brucellosis is a highly prevalent zoonotic disease caused by Brucella spp. Brucella suis S2 vaccination is an effective strategy to prevent animal brucellosis. However, S2 induces antibodies against the smooth lipopolysaccharide,making it challenging to distinguish field infected from vaccinated livestock. Early and accurate diagnosis is essential for infection control and prevention. In this study, we aimed to develop a quick and accurate assay to distinguish the BrucellaS2 vaccine strain from closely related B. abortus and B. melitensis.

Methods

Whole-genome sequencing of B. suis S2 was performed, and the sequence was compared with that of the genomes of B. abortus and B. melitensis. One specific gene, GL_0002189, was selected as a marker to differentiate the BrucellaS2vaccine strain from B. abortus and B. melitensis. A loop-mediated isothermal amplification (LAMP) assay was developed, based on the GL_0002189 gene, and then assessed for target specificity, lower limit of detection, and repeatability.

Results

Our results revealed that there was no cross-reaction with other strains, and the LAMP assay displayed high sensitivity for detecting S2 with a minimum detection limit of 18.9×103 copies/µL DNA input, it is nearly 100 times higher than conventional PCR technology. Concordance between the LAMP assay and a conventional polymerase chain reaction method was assessed using 54 blood samples collected from sheep with suspected brucellosis. Total concordance between the two assays was 92.6%, without a significant difference (p > 0.05) in the test results.

Conclusion

This is the first report of a LAMP assay for the detection of the B. suis S2vaccine strain. Our approach can be helpful for the control and eradication of brucellosis, and its simplicity in requiring no specialized equipment or personnel makes it useful for implementation in resource-limited settings as well as for field use.

Combining Direct PCR Technology and Capillary Electrophoresis for an Easy-to-Operate and Highly Sensitive Infectious Disease Detection System for Shrimp

Infectious diseases are considered the greatest threat to the modern high-density shrimp aquaculture industry. Specificity, rapidity, and sensitivity of molecular diagnostic methods for the detection of asymptomatic infected shrimp allows preventive measures to be taken before disease outbreaks. Routine molecular detection of pathogens in infected shrimp can be made easier with the use of a direct polymerase chain reaction (PCR). In this study, four direct PCR reagent brands were tested, and results showed that the detection signal of direct PCR in hepatopancreatic tissue was more severely affected. In addition, portable capillary electrophoresis was applied to improve sensitivity and specificity, resulting in a pathogen detection limit of 25 copies/PCR-reaction. Juvenile shrimp from five different aquaculture ponds were tested for white spot syndrome virus infection, and the results were consistent with the Organization for Animal Health’s certified standard method. Furthermore, this methodology could be used to examine single post larvae shrimp. The overall detection time was reduced by more than 58.2%. Therefore, the combination of direct PCR and capillary electrophoresis for on-site examination is valuable and has potential as a suitable tool for diagnostic, epidemiological, and pathological studies of shrimp aquaculture.

Proteomic Analysis of Spore Surface Proteins and Characteristics of a Novel Spore Wall Protein and Biomarker, EhSWP3, from the Shrimp Microsporidium Enterocytozoon hepatopenaei (EHP)

Enterocytozoon hepatopenaei, a spore-forming and obligate intracellular microsporidium, mainly infects shrimp and results in growth retardation and body length variation, causing huge economic losses to the Asian shrimp aquaculture industry. However, the lack of a full understanding of the surface proteins of spores associated with host infection has hindered the development of technologies for the detection of EHP. In this study, the surface proteins of EHP spores were extracted using the improved SDS method, and 130 proteins were identified via LC-MS/MS analysis. Bioinformatic analysis revealed that these proteins were enriched in biological processes (67), cellular components (62), and molecular functions (71) based on GO terms. KEGG pathway analysis showed that 20 pathways, including the proteasome (eight proteins) and the fatty acid metabolism (15 proteins), were enriched. Among 15 high-abundance surface proteins (HASPs), EhSWP3 was identified as a novel spore wall protein (SWP), and was localized on the endospore of the EHP spores with an indirect immunofluorescence and immunoelectron microscopy assay. Polyclonal antibodies against EhSWP3 showed strong species specificity and high sensitivity to the hepatopancreas of EHP-infected shrimp. As a specific high-abundance protein, EhSWP3 is therefore a promising target for the development of immunoassay tools for EHP detection, and may play a crucial role in the invasion of EHP into the host.

Isothermal Nucleic Acid Amplification Technologies for the Detection of Equine Viral Pathogens

Simple Summary

Equine viral diseases remain a prominent concern for human and equine health globally. Many of these viruses are of primary biosecurity concern to countries that import equines where these viruses are not present. In addition, several equine viruses are zoonotic, which can have a significant impact on human health. Current diagnostic techniques are both time consuming and laboratory-based. The ability to accurately detect diseases will lead to better management, treatment strategies, and health outcomes. This review outlines the current modern isothermal techniques for diagnostics, such as loop-mediated isothermal amplification and insulated isothermal polymerase chain reaction, and their application as point-of-care diagnostics for the equine industry.

Abstract

The global equine industry provides significant economic contributions worldwide, producing approximately USD $300 billion annually. However, with the continuous national and international movement and importation of horses, there is an ongoing threat of a viral outbreak causing large epidemics and subsequent significant economic losses. Additionally, horses serve as a host for several zoonotic diseases that could cause significant human health problems. The ability to rapidly diagnose equine viral diseases early could lead to better management, treatment, and biosecurity strategies. Current serological and molecular methods cannot be field-deployable and are not suitable for resource-poor laboratories due to the requirement of expensive equipment and trained personnel. Recently, isothermal nucleic acid amplification technologies, such as loop-mediated isothermal amplification (LAMP) and insulated isothermal polymerase chain reaction (iiPCR), have been developed to be utilized in-field, and provide rapid results within an hour. We will review current isothermal diagnostic techniques available to diagnose equine viruses of biosecurity and zoonotic concern and provide insight into their potential for in-field deployment.