High-titre antibodies to a foreign epitope elicited by affinity-purified hybrid LamB proteins

A monoclonal antibody to the LamB protein, named LBS-1, was developed and characterized. It was then covalently bound to Sepharose and used to purify hybrid LamB proteins from Escherichia coli crude extracts. A peptide of the interferon-γ (IFN-γ) NH2-terminal region, inserted within the LamB protein, was used as a model to assess immune response in mice injected with sonicated E. coli extract or with affinity-purified hybrid LamB protein. None of the mice immunized with the whole bacterial extract produced antibodies to IFN-γ. On the other hand, all the mice immunized with the purified protein developed high-titre anti-IFN-γ antibodies. These results might be due to the presence of bacterial components capable of masking the LamB protein to the immune system. The use of affinity-purified LamB proteins may constitute in some instances a more effective way of generating an immune response against foreign epitopes as opposed to whole bacterial antigens.