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

Ai Ai,Hua Hua,Zhang Zhang,Chen Chen,Wu Wu,Xie Xie,Liang Liang,Wang Wang,Peng Peng

doi:10.3390/vaccines7040176

Ai Ai, Hua Hua + Show 7 more

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https://doi.org/10.3390/vaccines7040176

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Abstract

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.

Highlights

Bordetella bronchiseptica is a small, Gram-negative, rod-shaped bacterium belonging to genus bordetella, recognized as a primary and secondary pathogenic bacterium of the upper respiratory tract in several mammals especially in dogs and in pigs [1]
Results of ELISA assays showed that the titers of IgG, IgA, secretory IgA (sIgA), IgG1, and IgG2a in piglets receiving live (QH09) or inactivated (HH0809) vaccines were significantly increased after immunization (Figure 3 and Table 3)
Results of ELISA assays showed that the titers of IgG, IgA, sIgA, IgG1, and IgG2a in piglets receiving live (QH09) or inactivated (HH0809) vaccines were significantly increased after receiving live (QH09) or inactivated (HH0809) vaccines were significantly increased after immunization immunization (Figure 3 and Table 3)

Summary

Introduction

Bordetella bronchiseptica is a small, Gram-negative, rod-shaped bacterium belonging to genus bordetella, recognized as a primary and secondary pathogenic bacterium of the upper respiratory tract in several mammals especially in dogs and in pigs [1]. B. bronchiseptica mainly causes respiratory tract infections including atrophic rhinitis, pneumonia, tracheitis, and it is a main causative agent of porcine respiratory disease complex (PRDC) [2]. These diseases are of high economic importance to the global animal industry. Inactivated vaccines have been used in pig industry for many years, their effects are limited. Live vaccines are capable of providing more effective protection, as B. bronchiseptica live vaccines are capable of inducing mucosal secretory IgA (sIgA) antibodies in addition to the systemic immunity [4,5]. The live vaccines can cause self-limiting, asymptomatic infection and produce immune responses closest to those induced by natural infection [6]

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