Actinobacillus pleuropneumoniae is the causative pathogen of porcine
pleuropneumonia, which results in large economic losses in the pig industry worldwide. There are, however, no effective
subunit vaccines are available in the market owing to the various serotypes and the absence of cross-protection against this pathogen. Therefore, the selection of protective components is of great significance for
vaccine development. We previously showed that trimeric
autotransporter adhesins are important
virulence factors of A. pleuropneumoniae. To determine the potential role in
vaccine development of the functional head domain (Apa2H1) of Apa2, a trimeric
autotransporter adhesin found in A. pleuropneumoniae, we obtained nature-like trimeric Apa2H1 using a prokaryotic expression system and co-culture of Apa2H1 with bone marrow derived dendritic cells (BMDCs) in vitro resulted in maturation of BMDCs, characterised by the up-regulation of CD83, MHC-II, CCR7, ICAM-I and the increased expression of factors related to B lymphoid cells stimulation, such as proliferation-inducing
ligand (APRIL),
B lymphocyte stimulator (BLyS) and
B cell activating factor (BAFF). The in vivo results showed that vaccination with Apa2H1 resulted in the robust production of
antigen-specific
antibodies, modestly induced mixed Th1 and Th2 immunity, impaired bacterial colonization and dissemination, and improved mouse survival rates. This study is the first to show that Apa2H1 is antigenic and can be used as a component of a
subunit vaccine against A. pleuropneumoniae
infection, providing valuable reference material for the development of an effective
vaccine against A. pleuropneumoniae.