Oral immunization with a novel attenuated Salmonella Gallinarum encoding infectious bronchitis virus spike protein induces protective immune responses against fowl typhoid and infectious bronchitis in chickens

Abstract

Fowl typhoid (FT), a septicemic disease caused by Salmonella Gallinarum (SG), and infectious bronchitis (IB) are two economically important avian diseases that affect poultry industry worldwide. Herein, we exploited a live attenuated SG mutant, JOL967, to deliver spike (S) protein 1 of IB virus (V) to elicit protective immunity against both FT and IB in chickens. The codon optimized S1 nucleotide sequence was cloned in-frame into a prokaryotic constitutive expression vector, pJHL65. Subsequently, empty pJHL65 or recombinant pJHL65-S1 plasmid was electroporated into JOL967 and the resultant clones were designated as JOL2068 and JOL2077, respectively. Our results demonstrated that the chickens vaccinated once orally with JOL2077 elicited significantly (p < 0.05) higher IBV-specific humoral and cell-mediated immunity compared to JOL2068 and PBS control groups. Consequently, on challenge with the virulent IBV strain at 28th day post-vaccination, JOL2077 vaccinated birds displayed significantly (p < 0.05) lower inflammatory lesions in virus-targeted tissues compared to control groups. Furthermore, 33.3% (2 of 6) of birds vaccinated with JOL2077 vaccine had shown virus recovery from tracheal tissues compared to 100% (6 of 6) recovery obtained in both the control groups. Against wild-type SG lethal challenge, both JOL2077 and JOL2068 vaccinated groups exhibited only 10% mortality compared to 80% mortality observed in PBS control group. In conclusion, we show that JOL2077 can induce efficient IBV- and carrier-specific protective immunity and can act as a bivalent vaccine against FT and IB. Further studies are warranted to investigate the potential of JOL2077 vaccine in broiler and young layer birds.Electronic supplementary materialThe online version of this article (10.1186/s13567-018-0588-9) contains supplementary material, which is available to authorized users.

Salmonella typhimurium Vaccine Candidate Delivering Infectious Bronchitis Virus S1 Protein to Induce Protection

“…The cytokines produced after antigenic stimulation in vitro are important parameters for defining the type of elicited immunity [14,49]. Our data showed that χ11246(pYA4545-S1) induced efficient IBV-specific cytokine responses involving both Th1 (IFN-γ and IL-12) and Th2 (IL-6), indicating a mixed type of immunity (Figure 4B).…”

“…Among these cytokines, the Th1 cytokine IFN-γ exerts a potent antiviral effect and promotes the activation of natural killer (NK) cells and macrophages to inhibit IBV replication and transmission with the host [51]. Additionally, IFN-γ can upregulate MHC-I and MHC-II molecules and induce macrophages to produce IL-12, nitric oxide, and superoxide, all of which are closely related to pathogen clearance [14]. IL-12 plays a crucial role in driving the differentiation of naive T cells toward the Th1 direction, which can stimulate the proliferation of T cells and promote the differentiation of Th0 cells into Th1 cells to trigger the cytotoxic activity of CTL and NK cells.…”

“…Inactivated IBVs are safe but costly, and elevated levels of protection will be achieved by co-administration with live attenuated vaccines [12,13]. Therefore, there is a need to develop a new vaccine, which not only does not depend on chicken embryos but is also cost-effective and capable of inducing high-efficiency and longlasting immune protection [14]. An alternative approach could be DNA vaccines, which offer durable expression cycle and good cellular responses with improved safety [15,16].…”

The aroA and luxS Double-Gene Mutant Strain Has Potential to Be a Live Attenuated Vaccine against Salmonella Typhimurium

“…In addition, the splenocytes were seeded into 6-well plates (WHB, Shanghai, China) at 1 × 10 6 cells/well and stimulated with 2 mL of media added with SAT52 whole-cell lysate for 24 h. Then, total RNA was extracted from the stimulated cells using a RNeasy Plus mini kit (Qiagen, GmbH, Hilden, Germany) and subsequently converted into cDNA using a High Capacity cDNA Reverse Transcription Kit (Applied Biosystems, Foster, CA, USA). The relative mRNA level of IL-4 and IFN-γ were quantified with real-time RT-PCR as previously described, with mouse GAPDH as internal control gene [ 32 ].…”

Antimicrobial peptides as an alternative to relieve antimicrobial growth promoters in poultry

“…are known to translocate from the intestinal and reproductive tract into intestinal tissue and, through systemic circulation, affect different organs, thus, provoking clinical lesions that vary depending on the health and immune status of the flock (Freitas Neto et al 2007). Infection can cause villus atrophy in the small intestine, affecting the absorptive surface of the intestine (Fasina et al 2010), decreasing flock performance and causing significant economic losses (Hajam et al 2018). The antibiotic treatment of infected birds results in prolonged and higher shedding levels in the faeces and is not a viable solution for controlling the spread of the infection in chickens (Smith andTucker 1975, 1980;Barrow et al 2012).…”