Effect of cheY deletion on growth and colonization in a Haemophilus parasuis serovar 13 clinical strain EP3

• A cheY deletion mutant of H. parasuis serovar 13 strain, EP3 was constructed.
• The cheY mutant strain has significantly reduced the growth rate, biofilms foremed, and agglutination.
• Apparent differences of serum-resistance between the wild strain and cheY mutant were not observed.

CheY, a response regulator of controlling the bacterial chemotactic swimming, can be modulated by either phosphorylation or acetylation to generate clockwise rotation of the flagella. Here, we researched the biological characteristics of cheY deletion mutant in Haemophilus parasuis, and found that the growth rate of this mutant was significantly slower compared with serovar 13 wild strain EP3. Additionally, the cheY mutant didn't show obvious sensitivity to porcine sera. The results of biofilm formation assay showed that H. parasuis cheY mutant produced less biofilm mass compared with wild strain. The H. parasuis cheY mutant reduced autoagglutination obviously. These findings were vital for revealing the function of cheY in growth, biofilm formation and autoagglutination. Thus, cheY plays a crucial role in growth and colonization in vivo of H. parasuis.