Update on the pathogenesis of Haemophilus parasuis infection and virulence factors

Haemophilus parasuis is the causative agent of Glässer's disease in pigs, a severe systemic disease that has led to increasing economic losses in the pig industry worldwide. The H. parasuis genome sequence has been completed, but the function and essentiality of the annotated genes remain largely unknown, especially virulence factors. The recent developments in the efficient genetic manipulation of H. parasuis have greatly facilitated the study of gene function, pathogenesis mechanisms and virulence factors. In this review, we provided update information regarding that (i) how the pathogen overcome host immune responses and cell barriers which were tightly associated with the pathogenesis, and (ii) the several recent identification of virulence factors were involved in evading the immune responses and cell barriers in H. parasuis.