ABSTRACT
Aphelenchoides besseyi (A. besseyi), a seed-borne parasitic nematode, is the causal agent of rice white tip disease (RWTD), which may result in a drastic loss of rice yield. Seed treatments are currently considered to be the most effective means of preventing the spread of RWTD. Therefore, the rapid, highly specific, and accurate detection of A. besseyi from rice seeds is crucial for the surveillance, prevention, and control of RWTD. Here, we describe a novel detection assay that combines recombinase polymerase amplification (RPA) and CRISPR/Cas12a to detect A. besseyi (termed RPA-Cas12a-Ab), with a low limit of detection (LOD) of 1 copy/µl of plasmid or 1:107 diluted DNA extracted from individual nematodes. To improve the user-friendliness, lateral flow strip assay (LFA) was adopted to visualize the detection result. The LOD of the RPA-Cas12a-Ab LFA assay was 1,000 copies/µl plasmid or 1:10 diluted DNA extracted from individual nematodes. The assay developed in this study was able to identify A. besseyi in 45 min with high accuracy and sensitivity without cross reaction with three closely related non-A. besseyi species. Thus, RPA-Cas12a-Ab is a rapid, sensitive, and specific detection system that requires no sophisticated equipment and shows promise for on-site surveillance of A. besseyi.
ABSTRACT
Based on an established common pharmacophore of HIV-1 non-nucleoside reverse transcriptase inhibitors (NNTTIs), a series of quinolin-2-one derivatives were synthesized and assayed for their in vitro activities against HIV-1 reverse transcriptase (RT) for the first time. Some of the tested compounds were active against HIV-1 RT. Compounds 4a2 and 4d2 showed inhibitory activities with IC(50) values of 0.21 and 0.15 mM, respectively, with a mode of interaction with RT residues of the allosteric pocket similar to that of efavirenz.
