Objective To construct a novel plasmid vector to facilitate the knocking out of genes in Helicobacter pylori. Methods pLYL03 was selected as a backbone for plasmid construction.Genetic elements of the pLYL03 plasmid were rearranged and redundant sequences were removed.The antibiotic resistance gene of pLYL03 was replaced with aphA to generate the kanamycin-resistant plasmid pSJHK.The plasmid pSJHK was used as the template plasmid for generating a double-cross-over recombination gene-knockout plasmid,and the...