How to make a vaccine lacking antibiotic resistance

摘要

A method of engineering a recombinant Listeria vaccine strain to express an HPV antigen, comprising: contacting a Listeria strain auxotrophic for D-alanine synthesis comprising mutations in a D-alanine racemase and a D-amino acid transferase gene in the Listeria's chromosome with a plasmid, the plasmid comprising a first nucleic acid sequence encoding a polypeptide that comprises a human papilloma virus E7 antigen, and a second nucleic acid sequence encoding a D-alanine racemase, wherein the plasmid does not confer antibiotic resistance to the auxotrophic Listeria vaccine strain, whereby the auxotrophic Listeria strain takes up the plasmid and the D-alanine racemase complements the mutation in the D-alanine racemase gene, wherein the auxotrophic Listeria strain grows in the absence of D-alanine, and wherein the first nucleic acid sequence is operably linked to a prokaryotic promoter, thereby engineering a recombinant Listeria vaccine strain to express the HPV antigen.