The role of Mac-1 as a receptor for Bordetella bronchiseptica infection of alveolar macrophages (AMphi) was examined using 6 strains (2 ATCC and 4 pathogenic field isolates) to assess B. bronchiseptica binding, uptake and replication in primary porcine AMphi. All B. bronchiseptica strains were rapidly killed by porcine serum in a dose- and time-dependent manner. However, heat-inactivated porcine serum (HIS) did not demonstrate any bacterial-killing activity, suggesting that complement may have a direct killing activity. All field isolates were more resistant to direct complement-mediated B. bronchiseptica killing. The uptake of B. bronchiseptica into AMphi was inhibited approximately 50% by antiMac-1 monoclonal antibodies in the medium. However, B. bronchiseptica phagocytosed in the presence of serum or HIS was not altered by anti-Mac-1 antibodies although more bacteria were internalized by addition of serum or HIS. These data suggest that Mac-1 is a target for direct uptake of B. bronchiseptica via opsoninindependent binding. The phagocytosed B. bronchiseptica, either via direct or serum-mediated binding, were efficiently killed by AMphi within 10 hr postinfection. This demonstrates that Mac-1-mediated B. bronchiseptica uptake is a bacterial killing pathway not leading to productive infections in AMphi.
Animals ; Antibodies, Bacterial/blood/immunology ; Bordetella bronchiseptica/*immunology ; Macrophage-1 Antigen/*immunology ; Macrophages, Alveolar/*immunology ; Phagocytosis ; Protein Binding ; Swine/*immunology/*microbiology

Dermonecrotic toxin (DNT) is identified as one of the most important virulence factor of Bordetella bronchiseptica. The complete coding sequence (4 356 bp) of the dnt gene was cloned into the prokaryotic expression vector pET-28a, and expressed in the Eschierichia coli BL21 (DE3) under IPTG (Isopropyl-beta-D-thiogalactopyranoside) induction. The recombinant His6-DNT protein showed immunological reactivity in the Western-blot analysis. The recombinant protein was purified from crude lysates of BL21 harboring pET-DNT with the purity of 93.2%. His6-DNT showed the dermonecrotic effects in the infant mouse assay. However, rabbit anti-serum against recombinant DNT protein could neutralize the dermonecrotic effects of native DNT to the infant mice in vivo. These findings suggest that the recombinant DNT protein retained the characteristics and immunogenicity of native DNT. Furthermore, this approach could be used to induce active immunity and serum immunoglobulin for production of a passive therapeutic reagent. In this study, we have shown that the recombinant His6-DNT protein retained the characteristics of native DNT of B. bronchiseptica, which built a good foundation for the further research on the structure and function of DNT.
Animals ; Animals, Newborn ; Bordetella bronchiseptica ; metabolism ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; Mice ; Neutralization Tests ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; immunology ; Transglutaminases ; biosynthesis ; genetics ; Virulence Factors, Bordetella ; biosynthesis ; genetics

Swine respiratory diseases induce severe economic losses in the swine industry worldwide. Several methods have been developed and applied to control these diseases. However, there are still problems of disease control in the swine industry. Recently, egg yolk antibodies have been found to offer several advantages for disease control in animals and humans. In a previous study (24), antibodies to several causative pathogens of swine respiratory diseases were developed. However, several problems remained, especially in terms of reduced laying rates. Therefore, experimental vaccines were reformulated with various bacterial antigens of the swine respiratory diseases. After immunizing hens with the antigens, antibody profiles and other effects including laying rates were investigated and compared to those of the previous study. Profiles of antibody titers were very similar with those of the previous study. However, side effects, such as depression, weakness, reduction of laying rates and mortality, were dramatically lowered and laying rates were increased in hens injected with certain experimental vaccines. In particular, laying rates of hens injected with vaccines against atrophic rhinitis were increased up to 84% by injecting a vaccine composed of only the DNTs of B. bronchiseptica and P. multocida D:4. Efficacies of the vaccines against swine pneumonic pasteurellosis and pleuropneumonia were very similar with those of the previous study. These results suggest that new vaccines could be effective in the production of egg yolk antibodies against the causative agents of swine respiratory diseases.
Actinobacillus pleuropneumoniae/classification/genetics/*immunology ; Animals ; Antibodies, Bacterial ; Antibody Formation ; Bacterial Outer Membrane Proteins/genetics/isolation & purification ; Bordetella bronchiseptica/classification/genetics/*immunology ; Egg Yolk/microbiology ; Female ; Immunoglobulins/*genetics ; Oviposition ; Pasteurella multocida/classification/genetics/*immunology ; Serotyping ; Swine

Fucoidan is a sulfated polysaccharide derived from brown seaweed, including Fucus vesiculosus. This compound is known to have immunostimulatory effects on various types of immune cells including macrophages and dendritic cells. A recent study described the application of fucoidan as a vaccine adjuvant. Vaccination is regarded as the most efficient prophylactic method for preventing harmful or epidemic diseases. To increase vaccine efficacy, effective adjuvants are needed. In the present study, we determined whether fucoidan can function as an adjuvant using vaccine antigens. Flow cytometric analysis revealed that fucoidan increases the expression of the activation markers major histocompatibility complex class II, cluster of differentiation (CD)25, and CD69 in spleen cells. In combination with Bordetella bronchiseptica antigen, fucoidan increased the viability and tumor necrosis factor-alpha production of spleen cells. Furthermore, fucoidan increased the in vivo production of antigen-specific antibodies in mice inoculated with Mycoplasma hyopneumoniae antigen. Overall, this study has provided valuable information about the use of fucoidan as a vaccine adjuvant.
Adjuvants, Immunologic/pharmacology ; Animals ; Antigens, Bacterial/*immunology ; Bacterial Vaccines/administration & dosage/*immunology ; Biomarkers/metabolism ; Bordetella bronchiseptica/*immunology ; Cells, Cultured ; Cytokines/*metabolism ; Female ; Flow Cytometry ; Fucus/*chemistry ; Gene Expression Regulation/drug effects ; Mice ; Mice, Inbred BALB C ; Mycoplasma hyopneumoniae/*immunology ; Polysaccharides/*pharmacology ; Spleen/metabolism