Chitosan microspheres containing Bordetella bronchiseptica antigens as novel vaccine against atrophic rhinitis in pigs.

The immune-stimulating activities of Bordetella bronchiseptica antigens containing dermonecrotoxin (BBD) loaded in chitosan microspheres (CMs) have already been reported in vitro and in vivo with a mouse alveolar macrophage cell line (RAW264.7) and mice. Therefore, this study attempted to demonstrate the successful induction of mucosal immune responses after the intranasal administration of BBD loaded in CMs (BBD-CMs) in colostrum-deprived pigs. The BBD was introduced to the CMs using an ionic gelation process involving tripolyphosphate (TPP). Colostrum-deprived pigs were then directly immunized through intranasal administration of the BBD-CMs. A challenge with a field isolate of B. bronchiseptica was performed ten days following the final immunization. The BBD-specific IgG and IgA titers, evident in the nasal wash and serum from the vaccinated pigs, increased with time (p<0.05). Following the challenge, the clinical signs of infection were about 6-fold lower in the vaccinated pigs compared with the nonvaccinated pigs. The grades for gross morphological changes in the turbinate bones from the vaccinated pigs were also significantly lower than the grades recorded for the nonvaccinated pigs (p<0.001). Therefore, the mucosal and systemic immune responses induced in the current study would seem to indicate that the intranasal administration of BBD-CMs may be an effective vaccine against atrophic rhinitis in pigs.

Monitoring the effect of PEGylation on polyethylenimine in vivo using nuclear imaging technique.

Polyethyleneimine (PEI) has been extensively investigated for use as a nonviral gene delivery vector due to its "proton sponge" mechanism. This work monitored the effect of PEGylation in vivo using nuclear imaging technique. We synthesized galactosylated PEI-PEG with different levels of PEG substitution ranging from 4.1 to 13.3 mol% of PEI amino groups. Validation of the differences of the in vivo distribution in the varying degrees of PEG substitution was performed using nuclear imaging with a gamma camera. PEGylated PEIs could easily label with reduced 99mTc because of their interaction with PEI amino groups. After systemic administration of 99mTc PEGylated Gal-PEIs, rapid accumulation in the liver, spleen, and lung was observed. However, with increasing amounts of PEG, the lung uptake was markedly reduced. These results demonstrate that nuclear imaging technique may be used as a basic screening tool for determining the optimized system of PEGylated Gal-PEIs. Once optimized, this system could be used as a hepatocyte targeted non-viral gene delivery vector which minimizes unspecific interactions with cellular blood components such as vessel endothelia and plasma proteins.