RESUMEN
The flagellin of Listeria monocytogenes is encoded by flaA gene;there is no detail report about the influence of flaA gene on the virulence of LM90 SB2.FlaA gene-deleted strain was constructed successfully with recombination technology.The influence of FlaA on LM90 SB2 virulence was evaluated by motility,BF formation,LD50,etc.Results showed that the colony morphology did not change,gene-deleted strain still had good genetic stability,but its growth was slow and the motility was decreased in the environment at 25 ℃,the morphological structure of the mutant BF was looser and incomplete,LD50 was increased from 4.27 × 106 cfu to 1.62 × 107 cfu.Results indicated that the flaA gene affected the flagellar formation of LM90 SB2 significantly,the ability of the BF formation and the virulence of the flaA deleted strain were decreased obviously.