Immunological and protective effects of Bordetella bronchiseptica subunit vaccines based on the recombinant N-terminal domain of dermonecrotic toxin

Comparative structural and immunological analysis of outer membrane proteins and dermonecrotic toxin in Bordetella bronchiseptica canine isolate

Bordetella bronchiseptica is a pathogen causing respiratory infections in mammals. With the improving understanding of companion animals' welfare, addressing the side effects of bordetella vaccine gains importance in dogs. Studies on diverse subunit vaccines are actively pursued in humans to safely and effectively control bordetellosis. Therefore, our objective was to develop a canine bordetella vaccine inspired by human vaccine development. We evaluated the immunogenicity of the two bacterial components: the outer membrane proteins (OMPs) and the dermonecrotic toxin (DNT) from a canine isolate of B. bronchiseptica. In-silico analysis identified eight domains of DNT, and Domain 3 was selected as the most promising antigen candidate. Additionally, the OMPs were extracted and examined using SDS-PAGE and Western blot analysis. The distinct immunological characteristic of OMPs and DNT-3 were examined individually and in combination. Gene expression and cytokine production were also evaluated in DH82 cells after stimulation with those antigens. Treatment with OMPs resulted in higher level of Th1 related cytokines, while DNT-3 induced a predominant response associated with Th17 and Th2 in the cytokine production. Synergistic effects were observed exclusively on IL-23, indicating increase of a potential risk of side effects when OMPs and DNT act together. These findings provide valuable insights into the reactogenicity of conventional Bordetella vaccines. Further, the presented preclinical data in this study offer an alternative method of the development for an optimal next-generation Bordetella vaccine for companion animals and humans, replacing the acellular vaccines containing both toxin and protein components.

Bordetella bronchiseptica and Bordetella pertussis: Similarities and Differences in Infection, Immuno-Modulation, and Vaccine Considerations

Bordetella pertussis and Bordetella bronchiseptica belong to the genus Bordetella, which comprises 14 other species. B. pertussis is responsible for whooping cough in humans, a severe infection in children and less severe or chronic in adults. These infections are restricted to humans and currently increasing worldwide. B. bronchiseptica is involved in diverse respiratory infections in a wide range of mammals. For instance, the canine infectious respiratory disease complex (CIRDC), characterized by a chronic cough in dogs. At the same time, it is increasingly implicated in human infections, while remaining an important pathogen in the veterinary field. Both Bordetella can evade and modulate host immune responses to support their persistence, although it is more pronounced in B. bronchiseptica infection. The protective immune responses elicited by both pathogens are comparable, while there are important characteristics in the mechanisms that differ. However, B. pertussis pathogenesis is more difficult to decipher in animal models than those of B. bronchiseptica because of its restriction to humans. Nevertheless, the licensed vaccines for each Bordetella are different in terms of formulation, route of administration and immune responses induced, with no known cross-reaction between them. Moreover, the target of the mucosal tissues and the induction of long-lasting cellular and humoral responses are required to control and eliminate Bordetella. In addition, the interaction between both veterinary and human fields are essential for the control of this genus, by preventing the infections in animals and the subsequent zoonotic transmission to humans.

Immune responses induced by a combined vaccination with a recombinant chimera of Mycoplasma hyopneumoniae antigens and capsid virus-like particles of porcine circovirus type 2

BACKGROUND

Mycoplasma hyopneumoniae (Mhp) and porcine circovirus type 2 (PCV2) are two important pathogens causing Mycoplasma pneumonia of swine (MPS) and porcine circovirus diseases and porcine circovirus-associated diseases (PCVDs/PCVADs), respectively, and resulted in considerable economic loss to the swine industry worldwide. Currently, vaccination is one of the main measures to control these two diseases; however, there are few combination vaccines that can prevent these two diseases. To determine the effect of combination immunization, we developed capsid-derived (Cap) virus-like particles (VLPs) of PCV2 and a new recombinant chimera composed of the P97R1, P46, and P42 antigens of Mhp. Then we investigated the immune responses induced by the immunization with this combination vaccine in mice and piglets.

RESULTS

The high level antibodies against three protein antigens (P97R1, P46, and P42 of Mhp) were produced after immunization, up to or higher than 1:400,000; the antibody levels in Pro group continuously increased throughout the 42 days for all the antigens tested. The lymphocyte proliferative response in PCV2 group was stronger than that in PBS, VP, Mhp CV in mice. The antibody levels for Cap remained stable and reached the peak at 35 DAI. The IFN-γ and IL-4 in sera were significantly enhanced in the Pro group than that in the negative control-VP group on Day 14 and 28 post-the first immunization in piglets.

CONCLUSIONS

Above all, the combination immunization could induce humoral and cellular immune responses against all four antigens in mice and piglets. Therefore, our approach is a simple and effective vaccination strategy to protect pigs against MPS and PCVD/PCVAD.

A Marker-Free Bordetella bronchiseptica aroA/bscN Double Deleted Mutant Confers Protection Against Lethal Challenge

Bordetella bronchiseptica is a leading cause of swine respiratory disorders which depict a great threat to well-flourished porcine industry. Vaccination remains an effective way for the prevention of B. bronchiseptica infections, as live B. bronchiseptica vaccines possess many advantages compared to inactivated vaccines and/or sub-unit vaccines, however, their safety is not up to the mark. In present study, we constructed marker-free aroA/bscN double deleted B. bronchiseptica QH09 through two-step homologous recombination strategy. Our data showed that QH09 attenuated virulence to mice compared with the parent aroA deleted B. bronchiseptica QH0814. We also found that QH09 meets the vaccine safety standards, upon challenge in piglets, did not cause any visible clinical signs or lesions on organs. Finally, we demonstrated that vaccination of QH09 activated the systemic as well as the mucosal immunity in pigs and provided protection against lethal bacterial challenge. These findings suggest that the aroA/bscN double deleted B. bronchiseptica QH09 may be an effective vaccine candidate, with safety assurance of animals against B. bronchiseptica infections.

Oral immunisation with Taishan Pinus massoniana pollen polysaccharide adjuvant with recombinant Lactococcus lactis-expressing Proteus mirabilis ompA confers optimal protection in mice

BACKGROUND

Proteus mirabilis poses a critical burden on the breeding industry, but no efficient vaccine is available for animals.

METHOD

A recombinant Lactococcus lactis expressing the ompA of P. mirabilis was used to develop a vaccine. The mucosal and systemic immune responses of the recombinant vaccine were evaluated in mice after oral immunisation. The inhibition on P. mirabilis colonisation of vaccines was also determined. Moreover, Taishan Pinus massoniana pollen polysaccharides (TPPPS) were used as adjuvants to examine the immunomodulatory effects.

RESULTS

The pure recombinant L. lactis vaccine significantly induced the production of specific IgA and IgG, IL-2, IL-4, IFN-γ, and T lymphocyte proliferation, and the immunised mice exhibited significant resistance to P. mirabilis colonisation. Notably, the TPPPS adjuvant vaccines induced higher levels of immune responses than the pure L. lactis.

CONCLUSIONS

The L. lactis as a vaccine vehicle combined with TPPPS adjuvant provides a feasible method for preventing P. mirabilis infection.