Pharmaceutical aspects of intranasal delivery of vaccines using particulate systems.

The nasal route offers a promising opportunity for the delivery of vaccines. This review analyses the opportunities and novel delivery strategies based on particulate systems for the nasal delivery of vaccines, including liposomes, proteosomes, virosomes, nano- and microparticulate systems, with and without adjuvants. The influence of pharmaceutical aspects of the particulate formulations on nasal delivery is analysed. Recently developed delivery devices for nasal vaccination are also described. Potential barriers to clinical and commercial success of some novel intranasal vaccines are critically evaluated. Although particulate systems may offer potential in the nasal delivery of vaccines by enhancing uptake by antigen-presenting cells, the real success in enhancement of vaccine delivery can only be achieved by careful design and manipulation of physicochemical properties of particulate vaccine delivery systems.

Modulation of immune response in mice immunised with an inactivated Salmonella vaccine and gavaged with Andrographis paniculata extract or andrographolide.

Gavage of mice, immunised with an inactivated S. typhimurium vaccine, with Andrographis paniculata extract [APE] or andrographolide [AND] resulted in an enhancement of Salmonella-specific antibody response and induction of cell-mediated response against salmonellosis. Mice were vaccinated with either one or two doses of killed S. typhimurium vaccine and fed two different quantities of APE or AND, for 14 days in mice immunised with one dose of the vaccine, and for 28 days in mice immunised with two doses of vaccine, respectively. Both APE and AND were found to enhance IgG antibody levels against S. typhimurium, the enhancement being statistically significant in mice receiving two doses of the vaccine. Splenocyte cultures, prepared from mice immunised with the killed Salmonella vaccine and treated with APE or AND, showed a remarkable increase in the production IFN-gamma following stimulation with the bacterial lysate, indicating an induction of Salmonella-specific cell-mediated response/immune response.

Evaluation of the immunogenicity of the P97R1 adhesin of Mycoplasma hyopneumoniae as a mucosal vaccine in mice.

The immunogenicity of P97 adhesin repeat region R1 (P97R1) of Mycoplasma hyopneumoniae, an important pathogenesis-associated region of P97, was evaluated in mice as a mucosal vaccine. Mice were immunized orally with attenuated Salmonella typhimurium aroA strain CS332 harbouring a eukaryotic or prokaryotic expression vector encoding P97R1. Local and systemic immune responses were analysed by ELISA on mouse sera, lung washes and splenocyte supernatants following splenocyte stimulation with specific antigens in vitro. Although no P97R1-specific antibody responses were detected in serum and lung washes, significant gamma interferon was produced by P97R1-stimulated splenocytes from mice immunized orally with S. typhimurium aroA harbouring either expression system, indicating induction of a cell-mediated immune response. These results suggested that live bacterial vectors carrying DNA vaccines or expressing heterologous antigens preferentially induce a Th1 response. Surprisingly, however, mice immunized with the vaccine carrier S. typhimurium aroA CS332 induced serum IgG, but not mucosal IgA, against P97R1 or S. typhimurium aroA CS332 whole-cell lysate, emphasizing the importance of assessing the suitability of attenuated S. typhimurium antigen-carrier delivery vectors in the mouse model prior to their evaluation as potential vaccines in the target species, which in this instance was pigs.

Comparative immunogenicity of M. hyopneumoniae NrdF encoded in different expression systems delivered orally via attenuated S. typhimurium aroA in mice.

The Mycoplasma hyopneumoniae ribonucleotide reductase R2 subunit (NrdF) gene fragment was cloned into eukaryotic and prokaryotic expression vectors and its immunogenicity evaluated in mice immunized orally with attenuated Salmonella typhimurium aroA CS332 harboring either of the recombinant expression plasmids. We found that NrdF is highly conserved among M. hyopneumoniae strains. The immunogenicity of NrdF was examined by analyzing antibody responses in sera and lung washes, and the cell-mediated immune (CMI) response was assessed by determining the INF-gamma level produced by splenocytes upon in vitro stimulation with NrdF antigen. S. typhimurium expressing NrdF encoded by the prokaryotic expression plasmid (pTrcNrdF) failed to elicit an NrdF-specific serum or secretory antibody response, and IFN-gamma was not produced. Similarly, S. typhimurium carrying the eukaryotic recombinant plasmid encoding NrdF (pcNrdF) did not induce a serum or secretory antibody response, but did elicit significant NrdF-specific IFN-gamma production, indicating induction of a CMI response. However, analysis of immune responses against the live vector S. typhimurium aroA CS332 showed a serum IgG response but no mucosal IgA response in spite of its efficient invasiveness in vitro. In the present study we show that the DNA vaccine encoding the M. hyopneumoniae antigen delivered orally via a live attenuated S. typhimurium aroA can induce a cell-mediated immune response. We also indicate that different live bacterial vaccine carriers may have an influence on the type of the immune response induced.