Location: Foodborne Toxin Detection and Prevention Research
2019 Annual Report
Accomplishments
1. Development of novel antibodies and detection assay to screen food samples for colistin-resistant bacteria. The recent discovery and rapid spread of mobile colistin-resistant gene, MCR-1, in bacteria is undermining our ability to treat bacterial infections and threatening human health and safety. ARS researchers at Albany, California, developed novel polyclonal and monoclonal antibodies against MCR-1 and MCR-2. An enzyme-linked immunosorbent assay (ELISA) established using these antibodies was able to detect 0.01 nanogram per milliliter of MCR-1 in buffer and 0.4 colony forming units per gram of meat, including ground chicken, pork, and beef, demonstrating strong tolerance to complex food matrices. This immunoassay could be used for rapid and reliable screening of food samples contaminated with colistin-resistant bacteria, making this an important tool for reducing the risk of foodborne infections with antibiotic resistant bacteria.
2. Development of a sensitive activity assay for staphylococcus enterotoxin serotype A. Staphylococcal enterotoxins (SEs) are some of the most commonly found food contamination agents. Assays to detect and quantify SEA ideally respond only to the active form of the toxin and this usually means employing live animal testing. Researchers at Albany, California, developed a cell-based assay for active SEA quantification in which Staphylococcal enterotoxins A (SEA) is presented by human B-cells to T-cells. The assay measures a decrease in levels of the T cell receptor Vbeta 9 (Vß9) and an increase of the IL2 cytokine. This is the first demonstration of a sensitive alternative assay that completely eliminated the use of animals for the quantitative detection of active SEA.
3. Effects of food processing on abrin bioavailability. Abrin is a highly potent plant toxin and a potential bioterror weapon. ARS researchers at Albany, California, evaluated the effectiveness of common food processing and pasteurization conditions against abrin in the presence or absence of foods. Selected food processing and pasteurization parameters used by processors for whole milk, non-fat milk, and liquid egg were insufficient to fully inactivate abrin activity. These studies suggest that different food matrices can have significant effects on the biological activity of abrin, information which could be used for food adulteration risk assessments.
4. Identification of a positive regulator of Stx2a in the human circulatory system. Stx2 is the cause of diarrhea-associated hemolytic uremic syndrome (HUS). The toxin released in the intestine by bacteria enters target organs such as the brain and kidneys by interacting with blood components. Among them, human serum amyloid P component (HuSAP) is considered a negative regulator that specifically binds to Stx2 and impairs its toxic action. Through collaborations with scientists at the University of Bologna, Italy, ARS researchers at Albany, California, identified a Toll-like receptor (TLR4) that formed protein complexes with Stx2 and inhibited its capture by HuSAP, thus allowing the toxin to target and damage human cells. This research provides important new insights on a new target for the development of therapeutic strategies for Stx2 associated-HUS.
5. Development of novel antibodies to botulinum neurotoxin serotype E. Botulinum neurotoxin serotype E (BoNT/E) outbreaks are most often observed in northern coastal regions and are associated with eating contaminated marine animals and other fishery products. ARS researchers at Albany, California, developed new mouse monoclonal antibodies for the sensitive detection of BoNT/E. Sandwich enzyme-linked immunosorbent assays (ELISAs) using these reagents detected as little as 0.2 ng/ml in standard buffer matrix and 10 ng/mL in fish product matrices. Development of sensitive and selective mAbs to BoNT/E would help in the initial screening of potential food contamination, speeding diagnosis and reducing use of laboratory animals. These reagents would be useful to kit manufacturing companies and regulatory agencies looking to improve BoNT/E detection.
Review Publications
Tam, C.C., Henderson II, T.D., Stanker, L.H., Cheng, L.W. 2018. Influence of food matrices on the stability and bioavailability of abrin. Toxins. 10(12):52. https://doi.org/10.3390/toxins10120502.
Tam, C.C., Flannery, A.R., Cheng, L.W. 2018. A rapid, sensitive, and portable biosensor assay for the detection of botulinum neurotoxin serotype A in complex food matrices. Toxins. 10(11):476. https://doi.org/doi:10.3390/toxins10110476.
He, X., Mavrici, D., Patfield, S.A., Rubio, F. 2018. Development of novel antibodies for detection of mobile colistin-resistant bacteria contaminated in meats. Scientific Reports. 8:16744. https://doi.org/10.1038/s41598-018-34764-2.
Brigotti, M., Arfilli, V., Carnicelli, D., Ricci, F., Tazzari, P., Ardissino, G., Scavia, G., Morabito, S., He, X. 2018. Soluble toll-like receptor 4 impairs the interaction of Shiga toxin 2a with human serum amyloid P component. Toxins. 10(9):379. https://doi.org/10.3390/toxins10090379.
Rasooly, R., Do, P.M., He, X., Hernlem, B.J. 2018. Alternative to animal use for detecting biologically active Staphylococcal enterotoxin type A. Toxins. 10(12):540. https://doi.org/10.3390/toxins10120540.
Bever, C.R., Scotcher, M., Cheng, L.W., Hnasko, R.M., Stanker, L. 2019. Development and characterization of monoclonal antibodies to botulinum neurotoxin type E. Toxins. 11:407. https://doi.org/10.3390/toxins11070407.
Rasooly, R., Bouton, J., Van Hecke, K., Van Calenbergh, S. 2018. Synthesis of pyrrolidine-based hamamelitannin analogues as quorum sensing inhibitors in Staphylococcus aureus. Beilstein Journal of Organic Chemistry. 14:2822-2828. https://doi.org/10.3762/bjoc.14.260.
Rasooly, R., Do, P.M., He, X., Hernlem, B.J. 2019. T cell receptor Vß9 in method to rapidly detect active staphylococcal enterotoxin type A without live animals. Toxins. 11:399. https://doi.org/10.3390/toxins11070399.
