Abstract: Haemophilus parasuis (Hps) is the pathogen of Glasser’s disease in pigs,which can cause serofibrinous pleurisy,pericarditis,peritonitis,arthritis and other diseases in pigs.There are many Hps serotypes,and there are differences in antigenic heterogeneity and pathogenicity among different strains.The pathogenic process of Hps infection involves a variety of virulence factors,such as biofilm,liposaccharide,capsule,fimbrial and other structural substances, as well as functional substances such as cytolethal distending toxin,ceramidase,α-2,3-sialyltransferase,and other outer membrane proteins，ect.A variety of virulence factors participate in the adhesion,invasion and colonization of Hps to host cells,and then cause inflammatory responses,including crossing the blood-brain barrier to cause encephalitis,and eventually cause damage to host cells and tissues and organs.Hps has a variety of complex immune evasion mechanisms,such as breaking through the epithelial cell barrier,degrading sIgA on the mucosal surface,resisting macrophage phagocytosis and the killing effect of complement,so as to help it resist the killing of the host immune system.The authors reviewed the different types of Hps virulence factors and their roles in the pathogenesis,and summarized the research progress of immune evasion mechanism of Hps,in order to provide new information for effective prevention and control of the disease and the development of novel vaccines.

Key words: Haemophilus parasuis; pathogenicity; virulence factor; immune evasion