Screening and identification of vancomycin anti-idiotypic antibodies for against Staphylococcus aureus from a human phage display domain antibody library.

Staphylococcus aureus is a common food-borne pathogenic microorganism that poses a serious threat to food quality and safety, and can do harm to human health. In the past, researchers relied on antibiotics to control Staphylococcus aureus, though very effective, yet it was also worrying in the aspect of bio-safety. In fact, anti-idiotypic antibody (Anti-Id) shows its potential to mimic some of the structural and biological functions of antigens. Therefore, in this study, based on Anti-Id theory and technology, we expect to obtain the vancomycin Anti-Id which can mimic vancomycin against Staphylococcus aureus from a human phage display domain antibody library. After four rounds of bio-panning, a total of 18 positive Anti-Ids were obtained. Among them, two Anti-Ids named Anti-Id-2C12 and Anti-Id-1F5 were identified as "β" type Anti-Ids, and afterwards they were selected for gene cloning and protein expression in prokaryotic expression system. As a result, a concentration of purified proteins with 568.6 μg/mL (Anti-Id-2C12) and 602.3 μg/mL (Anti-Id-1F5) were successfully obtained, and their minimum inhibitory concentration (MIC) values for Staphylococcus aureus were 125 and 200 μg/mL, respectively. As they are human heavy-chain domain antibodies, which were theoretically harmless to humans, they have the potential application value as preservatives in food and edible agricultural products.