Identification of conserved surface proteins as novel antigenic vaccine candidates of Actinobacillus pleuropneumoniae

Abstract

Actinobacillus pleuropneumoniae is an important swine respiratory pathogen causing great economic losses worldwide. Identification of conserved surface antigenic proteins is helpful for developing effective vaccines. In this study, a genome-wide strategy combined with bioinformatic and experimental approaches, was applied to discover and characterize surface-associated immunogenic proteins of A. pleuropneumoniae. Thirty nine genes encoding outer membrane proteins (OMPs) and lipoproteins were identified by comparative genomics and gene expression profiling as being-highly conserved and stably transcribed in the different serotypes of A. pleuropneumoniae reference strains. Twelve of these conserved proteins were successfully expressed in Escherichia coli and their immunogenicity was estimated by homologous challenge in the mouse model, and then three of these proteins (APJL_0126, HbpA and OmpW) were further tested in the natural host (swine) by homologous and heterologous challenges. The results showed that these proteins could induce high titers of antibodies, but vaccination with each protein individually elicited low protective immunity against A. pleuropneumoniae. This study gives novel insights into immunogenicity of the conserved OMPs and lipoproteins of A. pleuropneumoniae. Although none of the surface proteins characterized in this study could individually induce effective protective immunity against A. pleuropneumoniae, they are potential candidates for subunit vaccines in combination with Apx toxins.

Comparative proteomic analysis of the membrane proteins of two Haemophilus parasuis strains to identify proteins that may help in habitat adaptation and pathogenesis

“…However Chen et al [71] showed that PotD has lower or no protection against infection in a swine model, even though they induced high levels of antibodies. They also found that recombinant protein HbpA can induce high titers of antibodies and mediate opsonophagocytosis against A. pleuropneumoniae.…”

Genome-wide screening of lipoproteins in Actinobacillus pleuropneumoniae identifies three antigens that confer protection against virulent challenge

“…vaccine antigens are important approaches to overcome the deficiencies of current vaccines, and have received much attention in recent years 10 . Immunogenic proteins from the cell surface and outer membrane of A. pleuropneumoniae have been identified by phage display, immunoproteomic analysis or bioinformatic prediction 12,20,21 . In addition, antigens expressed during A. pleuropneumoniae infection were found using the in vivo-induced antigen technology 22 .…”

Efficacy Evaluation of Combination Vaccine of Recombinant C-Terminal Fragments of ApxIA, ApxIIA and ApxIIIA in Piglets

“…These vaccines do not effectively prevent colonization and are not widely cross protective (Tumamao et al 2004). As other pathogenic bacteria of multiple serotypes, a major point in the prevention of APP infections is to identify conserved antigens or proteins involved in immunogenicity, which may provide cross-protection against distinct APP serotype infections (Chen et al 2012;Haesebrouck et al 2004). The Apx toxins, such as ApxI, ApxII and ApxIII are virulence factors that play a predominant role in the pathogenesis of APP.…”