Improved Reverse Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) for the Rapid and Sensitive Detection of Yam mosaic virus

Recent advances and challenges in plant viral diagnostics

Accurate and timely diagnosis of plant viral infections plays a key role in effective disease control and maintaining agricultural productivity. Recent advances in the diagnosis of plant viruses have significantly expanded our ability to detect and monitor viral pathogens in agricultural crops. This review discusses the latest advances in diagnostic technologies, including both traditional methods and the latest innovations. Conventional methods such as enzyme-linked immunosorbent assay and DNA amplification-based assays remain widely used due to their reliability and accuracy. However, diagnostics such as next-generation sequencing and CRISPR-based detection offer faster, more sensitive and specific virus detection. The review highlights the main advantages and limitations of detection systems used in plant viral diagnostics including conventional methods, biosensor technologies and advanced sequence-based techniques. In addition, it also discusses the effectiveness of commercially available diagnostic tools and challenges facing modern diagnostic techniques as well as future directions for improving informed disease management strategies. Understanding the main features of available diagnostic methodologies would enable stakeholders to choose optimal management strategies against viral threats and ensure global food security.

Sensitive and Visual Detection of Brassica Yellows Virus Using Reverse Transcription Loop-Mediated Isothermal Amplification-Coupled CRISPR-Cas12 Assay

Brassica yellows virus (BrYV) is an economically important virus on cruciferous species. In this study, a one-pot reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay coupled with the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas12a system was developed for the detection of BrYV. The limit of detection of this method reached 32.8 copies of the BrYV ORF5, which is 100-fold more sensitive than the RT-LAMP method. Moreover, there was no cross-reactivity with other rapeseed-infecting RNA viruses or poleroviruses. We dried the CRISPR/Cas12a reagent in a trehalose and pullulan mixture to retain its efficacy at the RT-LAMP temperature of 63°C in order to allow portable BrYV detection in a water bath. The entire process can be performed in about 1 h, and a positive result can be rapidly and conveniently detected using a handheld UV lamp. In the field, the RT-LAMP-CRISPR/Cas12a assay was accurate and had higher sensitivity than RT-LAMP and reverse transcription-polymerase chain reaction assays. The novel RT-LAMP-CRISPR/Cas12a assay allows convenient, portable, rapid, low-cost, highly sensitive, and specific detection of BrYV and has great potential for on-site monitoring of BrYV.

Development of Polyclonal Antibodies and a Serological-Based Reverse-Transcription Loop-Mediated Isothermal Amplification (S-RT-LAMP) Assay for Rice Black-Streaked Dwarf Virus Detection in Both Rice and Small Brown Planthopper

Rice black-streaked dwarf virus (RBSDV) infects rice and maize, and seriously affects rice yields in main rice-producing areas. It can be transmitted via small brown planthopper (SBPH: Laodelphax striatellus Fallén). To more rapidly, sensitively, and highly throughput diagnose RBSDV in the wild condition, we first purified the recombinant His-CPRBSDV protein, and prepared the polyclonal antibodies against the His-CPRBSDV protein (PAb-CPRBSDV). Based on the PAb-CPRBSDV, we developed a series of serological detections, such as Western blot, an enzyme-linked immunosorbent assay (ELISA), and a dot immunoblotting assay (DIBA). Furthermore, we developed a serological-based reverse-transcription loop-mediated isothermal amplification assay (S-RT-LAMP) that could accurately detect RBSDV in the wild. Briefly, the viral genomic dsRNA together with viral CP were precipitated by co-immunoprecipitation using the PAb-CPRBSDV, then the binding RNAs were crudely isolated and used for RT-LAMP diagnosis. Using the prepared PAb-CPRBSDV, four serology-based detection methods were established to specifically detect RBSDV-infected rice plants or SBPHs in the wild. The method of S-RT-LAMP has also been developed to specifically, high-throughput, and likely detect RBSDV in rice seedlings and SBPHs simultaneously. The antiserum prepared here laid the foundation for the rapid and efficient detection of RBSDV-infected field samples, which will benefit for determination of the virulence rate of the transmission vector SBPH and outbreak and epidemic prediction of RBSDV in a rice production area.