Culturable bacteria resident on lettuce might contribute to accumulation of human noroviruses

Authors: LIU, DANLEI - Shanghai Jiaotong University; ZHANG, ZILEI - Shanghai Jiaotong University; LIAO, NONBO - Zhejiang Academy Of Agricultural Sciences; ZOU, SONGYAN - Shanghai Jiaotong University; TANG, HAOXUAN - Shanghai Jiaotong University; Tian, Peng; WU, QINGPING - Guangdong Academy Of Agricultural Sciences; WANG, DAPENG - Shanghai Jiaotong University

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2019
Publication Date: 12/26/2019
Citation: Liu, D., Zhang, Z., Liao, N., Zou, S., Tang, H., Tian, P., Wu, Q., Wang, D. 2019. Culturable bacteria resident on lettuce might contribute to accumulation of human noroviruses. International Journal of Food Microbiology. 317. https://doi.org/10.1016/j.ijfoodmicro.2019.108492.
DOI: https://doi.org/10.1016/j.ijfoodmicro.2019.108492

Interpretive Summary: Human noroviruses (HuNoVs) is the primary non-bacterial pathogen causing acute gastroenteritis worldwide. Romaine lettuce is an important food-related vehicle for HuNoV transmission. The histo-blood group antigens (HBGA)-like substances in lettuce are major ligands for binding of HuNoV. However, it is unclear the factors involved in interaction between HuNoV and lettuce leaves. In this study, 27 bacteria strains with different colony morphologies were isolated from lettuce collected in the field. The HBGA-like substances, which were synthesized and secreted to the outermost of extracellular polymeric substances (EPS) by isolated bacteria, were recognized by the monoclonal antibodies of HBGAs. Among which, an isolate, SC006, was found to express the most diverse types of HBGA-like substances including type B, H, Lewis a, Lewis b and Lewis x. Through the optimization of culture condition, the strains were found to express HBGA-like substances when cultured in oligotrophic medium. The binding abilities of HuNoVs were verified. The interaction between the isolated bacteria with HuNoVs proposed a possibility that bacteria colonized on the surface of lettuce which can express HBGA-like substances under outer stress, may provide specifically recognition and binding, protection and means of transmission for HuNoVs.

Technical Abstract: Human noroviruses (HuNoVs) is the primary non-bacterial pathogen causing acute gastroenteritis worldwide. Romaine lettuce is an important food-related vehicle for HuNoV transmission. The histo-blood group antigens (HBGA)-like substances in lettuce are major ligands for binding of HuNoV. However, it is unclear the factors involved in interaction between HuNoV and lettuce leaves. In this study, 27 bacteria strains with different colony morphologies were isolated from lettuce collected in the field. The HBGA-like substances, which were synthesized and secreted to the outermost of extracellular polymeric substances (EPS) by isolated bacteria, were recognized by the monoclonal antibodies of HBGAs. Among which, an isolate, SC006, was found to express the most diverse types of HBGA-like substances including type B, H, Lewis a, Lewis b and Lewis x. Through the optimization of culture condition, the strains were found to express HBGA-like substances when cultured in oligotrophic medium. The binding abilities of HuNoVs were verified. The interaction between the isolated bacteria with HuNoVs proposed a possibility that bacteria colonized on the surface of lettuce which can express HBGA-like substances under outer stress, may provide specifically recognition and binding, protection and means of transmission for HuNoVs.