文摘
Haemophilus parasuis is the causative agent of Gl?sser¡¯s disease. To investigate the role of lipooligosaccharide (LOS) in H. parasuis infection, ¦¤opsX, ¦¤rfaF and ¦¤waaQ mutants defective in expressing opsX, rfaF and waaQ heptosyltransferases were constructed by transformation. Compared to the wild-type SC096 strain, the ¦¤opsX and ¦¤rfaF mutants, but not the ¦¤waaQ mutant, produced severely truncated LOS. The mutants exhibited various degrees of reduction in resistance to complement-mediated killing in porcine and rabbit sera. In addition, the ¦¤opsX and ¦¤rfaF mutant strains showed impaired ability to adhere to and invade porcine kidney epithelial cells (PK-15) and porcine umbilical vein endothelial cells, indicating roles for heptose I and II residues in the interaction with host cells. The ¦¤waaQ mutant strain, with no obvious truncation of LOS structure, did not exhibit significant defects in adhesion to and invasion of host cells. This study provides insight into the contribution of the inner core oligosaccharide, especially heptose I and heptose II residues, to the virulence-associated properties of H. parasuis.