Establishment and application of assays for evaluating competitive colonization of Vibrio parahaemolyticus in infant mouse intestinal track

Objective To establish an infant mouse model to evaluate the competitive colonization of Vibrio parahaemolyticus in mouse intestinal track and provide evidence for the research of pathogenicity of V. parahaemolyticus. Methods The -galactosidase gene lacZ of Vibrio cholerae was amplified and cloned into the V. parahaemolyticus RIMD2210633(WT) genome to construct WT- lacZ strain. Then, the colonization ability of the WT-lacZ strain in 5-day-old CD-1 suckling mice intestine was compared with that of the WT strain and an environment-isolated VP1907 strain, respectively. Results The colony of WT-lacZ strain was blue on the X-Gal LB agar plate. The WT-lacZ strain showed no significant change in colonization compared with WT strain, suggesting that the WT-lacZ strain can substitute the WT strain in colonization competition study in vivo. The result of the in vivo competition assay showed that the competitive index between the WT-lacZ strain and VP1907 strain was 0.1 approximately, indicating significantly higher colonization of the WT strain than that of the VP1907 strain. Conclusion A new infant mouse model using RIMD2210633 strain was successfully established for evaluating the intestinal competitive colonization of V. parahaemolyticus and used to compare the competitive colonization between highly virulent strains and non-virulent strains isolated in environment.