Evaluation of the recombinant proteins RlpB and VacJ as a vaccine for protection against Glaesserella parasuis in pigs

Abstract

Background: Glaesserella parasuis, the causative agent of Glӓsser's disease, is widespread in swine globally resulting in significant economic losses to the swine industry. Prevention of Glӓsser's disease in pigs has been plagued with an inability to design broadly protective vaccines, as many bacterin based platforms generate serovar or strain specific immunity. Subunit vaccines are of interest to provide protective immunity to multiple strains of G. parasuis.Selected proteins for subunit vaccination should be widespread, highly conserved, and surface exposed. Results: Two candidate proteins for subunit vaccination (RlpB and VacJ) against G. parasuis were identified using random mutagenesis and an in vitro organ culture system. Pigs were vaccinated with recombinant RlpB and VacJ, outer membrane proteins with important contributions to cellular function and viability. Though high antibody titers to the recombinant proteins and increased interferon-γ producing cells were found in subunit vaccinated animals, the pigs were not protected from developing systemic disease.Conclusions: It appears there may be insufficient RlpB and VacJ exposed on the bacterial surface for antibody to bind, preventing high RlpB and VacJ specific antibody titers from protecting animals from G. parasuis. Additionally, this work confirms the importance of utilizing the natural host species when assessing the efficacy of vaccine candidates.

Assessment of the Macrophage Scavenger Receptor CD163 in Mediating Glaesserella parasuis Infection of Host Cells

“…For example, with the usage of antibiotics, more antibiotic resistance genes have been conferred to G. parasuis due to the fact of its evolution [ 8 , 9 ]. Moreover, the actual protection effect of some candidate vaccines in pigs is still nonideal [ 10 , 11 ]. An earlier study has shown that 10% of all experimentally infected pigs were fully resistant, suggesting that there are differences in susceptibility to G. parasuis infection in pigs.…”

Maintenance of bacterial outer membrane lipid asymmetry: insight into MlaA

“…Focusing on amino acid sequence analysis, the mlaA sequence is highly conserved even when a bacterium is isolated from a different host. Comparative analysis of different strains of Pasteurella multocida [ 81 ] and Glaesserella parasuis [ 82 , 83 ] show 99.6 to 100% identity in amino acid sequences within species. The retrieved NCBI sequences from Indian strains of P. multocida (cattle, buffalo, duck, pig, sheep, quail, rabbit, chicken and turkey) show > 98% amino acid similarity, and proline, aspartic acid, glutamic acid, serine and threonine are the variable amino acids [ 84 ].…”

“…Focusing on the impairment in colony morphotype, Burkholderia ( B. dolosa PC543 and B. cenocepacia K56-2) produce smaller colonies on LB agar in the absence of mlaA , whereas in P. aeruginosa [ 13 ], X. citri subsp. citri [ 82 ] and E. coli K-12 [ 13 ], no phenotypic differences were visualized.…”

Immunogenicity and protection against <i>Glaesserella parasuis</i> serotype 13 infection after vaccination with recombinant protein LolA in mice

“…G. parasuis negatively affects the modern swine industry and is an important bacterial disease that should be prevented [ 29 , 30 ]. Glässer’s disease has traditionally been prevented using intensive feeding management techniques, antibiotics, and inactivated vaccines [ 10 , 20 ]. Antibiotics exert a certain protective effect against Glässer’s disease.…”