Two binding epitopes modulating specificity of immunoassay for β-agonist detection: Quantitative structure-activity relationship

Risk Assessment of Veterinary Drug Residues in Pork on the Market in the People's Republic of China

ABSTRACT

Veterinary drugs, including antibiotics, antiparasitics, and growth promoters, are widely used in animal husbandry. Veterinary drug residues are key issues of food safety because they arouse public concern and can seriously endanger the health of consumers. To assess the risk of veterinary drug residues in pork sold in the People's Republic of China, the potential veterinary drug residue risks in imported and domestic pork were analyzed based on regulatory differences and veterinary drug residue safety incidents. For imported pork, a risk assessment model was established based on the differences in veterinary drug residue limits for the People's Republic of China, Brazil, the United States, Australia, Thailand, and Russia combined with comprehensive evaluation methods. The potential risk of veterinary drug residues in U.S. pork was the highest, and that in Brazilian pork was the lowest. For domestic pork, the distribution and aggregation of veterinary drug residue safety incidents in the People's Republic of China was analyzed from 2015 to 2019 with a geographic information system. This study provides new insights into the safety of pork on the Chinese market and a scientific basis for formulating targeted supervision and early warning strategies.

HIGHLIGHTS

Current Advances in Immunoassays for the Detection of β2-Agonists

β2-agonists are a group of synthetic phenylethanolamine compounds which are traditionally used for treating bronchospasm. These compounds can also increase skeletal muscle mass and decrease body fat. The illegal use of β2-agonists in food-producing animals results in residue of β2-agonists in edible tissues and causes adverse health effects in humans. Thus, the detection of β2-agonists at trace level in complex sample matrices is of great importance for monitoring the abuse of β2-agonists. Many methods have been developed to detect β2-agonists. Among them, a variety of antigen–antibody interaction-based techniques have been established to detect β2-agonists in various samples, including animal feed, urine, serum, milk, tissues and hair. In this review, we summarized current achievement in the extraction of β2-agonists from testing samples and detection of β2-agonists using immunological techniques. Future perspectives were briefly discussed.

Conformational adaptability determining antibody recognition to distomer: structure analysis of enantioselective antibody against chiral drug gatifloxacin

Enantioselective antibodies have great potential to separate and detect chiral compounds. However, cross-reactivity of enantioselective antibodies to the distomer may limit the application. An in-depth understanding of interactions between antibodies and chiral drugs could be helpful to investigate antibody recognition to the distomer. In this study, a monoclonal antibody against chiral quinolone S-(−)-gatifloxacin (S-GAT) was produced and its Fab fragment was prepared by proteolysis. The S-GAT Fab exhibited 10% cross-reactivity against the R-enantiomer compared to that of the S-enantiomer in an indirect competitive enzyme-linked immunosorbent assay (icELISA). The crystal structures of the S-GAT Fab apo form and complex with S-GAT were analyzed, and molecular docking of the R-enantiomer was carried out. The ligand conformation was further studied using molecular dynamics simulations. The results showed that the distomer R-enantiomer could enter the chiral center recognition region of the antibody by adjusting the piperazine ring conformation. Meanwhile, the antibody binding cavity had obvious conformational adaptability during ligand binding. It demonstrated that conformational change of both ligand and antibody was the key reason why antibodies recognize the distomer. Restricting conformational adaptability could improve the enantioselective recognition ability of antibodies. This study provided a new explanation for the cross-reactivity of enantioselective antibodies to the distomer, and could help to modulate antibody enantioselectivity for immunoassay of chiral drugs.

The conformational adaptability of both antibody and ligand could determine the antibody enantioselectivity in chiral drug immunoassay.