Search

Highlights • Coated PEDV-loaded microspheres were developed by centrifugal granulation-fluidized bed coating. • Coated PEDV-loaded microspheres could protect PEDV antigens against the complex gastrointestinal environment in vitro and in vivo. • Oral vaccination with coated PEDV-loaded microspherescould induce higher levels of PEDV-specific antibodies in weaned piglets than the orally delivered PEDV only group. Abstract Porcine epidemic diarrhea virus (PEDV) infects pigs of all ages by invading villous epithelial cells of the small intestine causing severe diarrhea with high mortality rate in suckling piglets. Mucosal immunity is believed to play an important role in PEDV control and mucosal delivery of vaccines induces mucosal immunity more efficiently than parenteral vaccination. In this study, coated PEDV-loaded microspheres with the size range of 700–900 μm in diameter were developed by centrifugal granulation-fluidized bed coating and demonstrated as an effective oral delivery system to protect PEDV antigens against the complex gastrointestinal environment by detecting the live virus particles in microspheres after the simulated gastric fluid treatment and the PEDV RNA in fecal swabs collected from all weaned piglets (100%) orally inoculated with coated PEDV-loaded microspheres. Weaned piglets orally immunized with coated PEDV-loaded microspheres developed higher levels of PEDV-specific antibodies (IgG and IgA) in their sera and saliva than those negative control groups (p < 0.001 or p < 0.01). Furthermore, neutralization assays demonstrated that serum antibodies in coated PEDV-loaded microspheres groups could significantly inhibit virus infection in Vero cells, compared to PEDV only group (p < 0.05). Overall, our results indicate that the coated PEDV-loaded microspheres might serve as an effective way to induce PEDV-specific mucosal immunity in pigs against PEDV. [ABSTRACT FROM AUTHOR]

Since a novel hyper-virulent fowl adenovirus serotype 4 (FAdV-4) infection occurred in 2015, the novel FAdV-4 has been widely spreading across China, causing significant economic losses to the poultry industry. As the urgency of the issue calls for effective and efficient solutions, the present study investigated the possibility of the fiber-2 protein of the FAdV-4 to serve as a vaccine candidate against the novel FAdV-4. In the research, fiber-2 proteins were expressed in Escherichia coli , and then purified. To evaluate the immunogenicity of the recombinant fiber-2 protein, we investigated both the humoral and cellular immune responses in chickens immunized with fiber-2. The humoral immunity was assessed by detecting IgY antibodies and virus-neutralizing antibodies in chicken serum at 7, 14, 21 days post-immunization (dpi). We examined cellular immune responses by detecting CD3+CD4+ and CD3+CD8+ changes in chickens’ peripheral blood through using flow cytometry at 7, 14, 21 dpi. The cytokine production in the serum of the immunized chickens was detected by ELISA at 7, 14, 21 dpi to further explore the impact of the recombinant protein on the regulation of cytokines. The protective efficacy was determined by the survival rate of the immunized chickens challenged with the novel FAdV-4. The results show that the level of IgY antibodies of the chickens immunized with fiber-2 protein was significantly higher than that of the chickens immunized with an inactivated vaccine against FAdV-4. Moreover, 7 days after immunization, the CD4+ T-cell proliferative response of the chickens immunized with fiber-2 was significantly higher than that of the chickens immunized with the inactivated vaccine. Challenge experiment showed that the fiber-2 protein could provide full protection and the inactivated vaccine could provide 90 percent protection against the FAdV-4. These results suggest that the recombinant fiber-2 protein can be an ideal candidate for subunit vaccines against the disease. [ABSTRACT FROM AUTHOR]

PEDV variants, causing severe diarrhea in neonatal suckling piglets with a mortality rate up to 100%, have being epidemic since late 2010 in china. To meet the pressing need of safe and cost-efficient PED maternal vaccines against PEDV variant, we vaccinated growing piglets with a flagellin-adjuvanted PED vaccine rSF-COE-3D by injection at Houhai acupoint. The vaccination not only enhanced the antibody responses of serum IgG/IgA, mucosal IgA and serum neutralizing antibody, but also improved the production of IFN-γ and IL-4. Moreover, rSF-COE-3D could provide a better protection against the challenge of a high pathogenic PEDV variant, with less diarrhea pigs, less pigs with detectable PEDV shed, lower rank values of feces and less apparent lesions and inflammation in duodenum of the PEDV infected pigs. The improved protective efficiency of rSF-COE-3D compared with COE was mostly benefited from the enhanced production of serum IgA, mucosal IgA in feces and serum neutralizing antibody titers. Taken together, our data suggest that rSF-COE-3D would be a novel efficient PED vaccine. [ABSTRACT FROM AUTHOR]

Porcine epidemic diarrhea (PED) is an important re-emergent infectious disease and inflicts huge economic losses to the swine industry worldwide. To meet the pressing need of developing a safe and cost-efficient PED maternal vaccine, we generated three PED subunit vaccine candidates, using recombined Salmonella flagellin (rSF) as a mucosal molecular adjuvant. Domain D3 in rSF was replaced with COE domain of PEDV to generate rSF-COE-3D. COE fused to the flanking C′/N′ terminal of rSF yielded rSF-COE-C and rSF-COE-N. As a result, rSF-COE-3D could significantly improve COE specific antibody production including serum IgG, serum IgA, mucosal IgA and PEDV neutralizing antibody. Furthermore, rSF-COE-3D elicited more CD3 + CD8 + T cell and cytokine production of IFN-γ and IL-4 in mouse splenocytes. In summary, our data showed that rSF-COE-3D could improve specific humoral and mucosal immunity in mice, thus suggesting that rSF-COE-3D could be applied as a novel efficient maternal PED vaccine. [ABSTRACT FROM AUTHOR]