Direct injection of functional single-domain antibodies from E. coli into human cells.

TitleDirect injection of functional single-domain antibodies from E. coli into human cells.
Publication TypeJournal Article
Year of Publication2010
AuthorsBlanco-Toribio, A., S. Muyldermans, G. Frankel, and L. Ángel Fernández
JournalPLoS One
Date Published2010
KeywordsAntibodies, Antibodies, Monoclonal, Bacterial Proteins, Base Sequence, beta-Lactamases, Cell Line, Culture Media, Escherichia coli, HeLa Cells, Humans, Molecular Sequence Data, Oligonucleotides, Protein Engineering, Protein Structure, Tertiary, Protein Transport, Streptolysins

Intracellular proteins have a great potential as targets for therapeutic antibodies (Abs) but the plasma membrane prevents access to these antigens. Ab fragments and IgGs are selected and engineered in E. coli and this microorganism may be also an ideal vector for their intracellular delivery. In this work we demonstrate that single-domain Ab (sdAbs) can be engineered to be injected into human cells by E. coli bacteria carrying molecular syringes assembled by a type III protein secretion system (T3SS). The injected sdAbs accumulate in the cytoplasm of HeLa cells at levels ca. 10⁵-10⁶ molecules per cell and their functionality is shown by the isolation of sdAb-antigen complexes. Injection of sdAbs does not require bacterial invasion or the transfer of genetic material. These results are proof-of-principle for the capacity of E. coli bacteria to directly deliver intracellular sdAbs (intrabodies) into human cells for analytical and therapeutic purposes.

Alternate JournalPLoS ONE
PubMed ID21170340
PubMed Central IDPMC2999559
Grant List / / Wellcome Trust / United Kingdom