Enhancement of protective immune responses by oral vaccination with Saccharomyces cerevisiae expressing recombinant Actinobacillus pleuropneumoniae ApxIA or ApxIIA in mice

We previously induced protective immune response by oral immunization with yeast expressing the ApxIIA antigen. The ApxI antigen is also an important factor in the protection against Actinobacillus pleuropneumoniae serotype 5 infection; therefore, the protective immunity in mice following oral immunization with Saccharomyces cerevisiae expressing either ApxIA (group C) or ApxIIA (group D) alone or both (group E) was compared with that in two control groups (group A and B). The immunogenicity of the rApxIA antigen derived from the yeast was confirmed by a high survival rate and an ApxIA-specific IgG antibody response (p < 0.01). The highest systemic (IgG) and local (IgA) humoral immune responses to ApxIA and ApxIIA were detected in group E after the third immunization (p < 0.05). The levels of IL-1beta and IL-6 after challenge with an A. pleuropneumoniae field isolate did not change significantly in the vaccinated groups. The level of TNF-alpha increased in a time-dependent manner in group E but was not significantly different after the challenge. After the challenge, the mice in group E had a significantly lower infectious burden and a higher level of protection than the mice in the other groups (p < 0.05). The survival rate in each group was closely correlated to the immune response and histopathological observations in the lung following the challenge. These results suggested that immunity to the ApxIA antigen is required for optimal protection.

A predictive model for the level of sIgA based on IgG levels following the oral administration of antigens expressed in Sacchromyces cerevisiae

Oral vaccination may be the most efficient way of inducing an immune response at the remote mucosal site through the common mucosal immune network. Antigenspecific secretory IgA (sIgA) is the major immunoglobulin type generally detected in the secretions of experimental animals following an effective oral immunization. Actinobacillus pleuropneumoniae causing disease in the lung of pig initially interacts, colonizes, and infects the host tissues at the mucosal surface of the respiratory tract. Also, importantly for A. pleuropneumoniae protection, the quantity of sIgA in the lung had merits associated with the mucosal immunity. However, there is no simple method to monitor the level of sIgA as an indicator for the induction of local immune responses by an oral vaccination in the target tissue. Therefore, the relationship between sIgA and IgG was analyzed to evaluate the induction of local immune responses by an oral immunization with Saccharomyces cerevisiae expressing the apxIA and apxIIA genes of A. pleuropneumoniae in this study. The correlation coefficient of determination (r2 x 100) for paired samples in both vaccinated and control groups showed a significant positive-relationship between IgG in sera and sIgA in the lung or intestine. These results indicated that IgG antibody titers in sera could be useful to indirectly predict local immune response, and sIgA, in the lung or intestine to evaluate the efficacy of an oral vaccination.

Expression of apxIA of Actinobacillus pleuropneumoniae in Saccharomyces cerevisiae

Actinobacillus pleuropneumoniae is an important primary pathogen in pigs, in which it causes a highly contagious pleuropneumoniae. In our previous study, apxIA gene amplified from A. pleuropneumoniae Korean isolate by PCR with primer designed based on the N- and C-terminal of the toxin was cloned in TA cloning vector and sequenced. The nucleotide sequences of apxIA gene was reported to GeneBank with the accession numbers of AF363361. Identity of the Apx IA from the cloned gene in E. coli was proved by SDS-PAGE and Western blot. Yeast has been demonstrated to be an excellent host for the expression of recombinant proteins with uses in diagnostics, therapeutics and vaccine productions. Therefore, to use the yeast as a delivery system in new oral subunit vaccine, apxIA gene was subcloned into Saccharomyces cerevisiae, and ientified the expression of Apx IA protein. First, apxIA gene was amplified by PCR with the primers containing BamHI and SalI site at each end. Second, the DNA digested with BamHI and SalI was ligated into YEpGPD-TER vector, and transformed into S. cerevisiae 2805. Third, after identification of the correctly oriented clone, the 120-kDa of Apx IA protein expressed in S. cerevisiae 2805 was identified by SDS-PAGE and Western blot.

Anti-tumor Effect of Combined Betacarotene with X-irradiation in the Mouse Fibrosarcoma : Cytotoxicity and Tumor Growth Delay / 대한방사선종양학회지

PURPOSE: To investigate whether combined beta-carotene with X-irradiation has more enhanced radition response than X-irradiation or not, we performed a experiment about in vitro cytotoxicity of beta-carotene and/or X-irradiation in the fibrosarcoma cells, tumor growth delay of combined beta-caroten with/or X-irradiation in the mouse fibrosarcoma. MATERIALS AND METHODS: 2% emulsion of beta-carotene was serially diluted and used. X-irradiation was given by 6 MeV linear accelerator. The cytotoxicity of beta-carotene in vitro was evaluated from clonogenic assay. To compare the cytotoxicity between combined beta-carotene with X-irradiation and X-irradiation group, 2 mg/ml of beta-carotene was contacted to fibrosarcoma (FSaII) cells for 1 hour before X-irradiation. For the tumor growth delay, single 20 Gy was given to FSaII tumor bearing C3H/N mice whic was classified as beta-crotene with X-irradiation group (n=6) and X-irradiation alone group (n=5). 0.2 ml of 20 mg/kg of beta-carotene were i.p. injected to mice 30 minute before X-irradiation in the beta-crotene with X-irradiation group. The tumor growth delay defined as the time which reach to 1,000 mm3 of tumor volume. RESULT: (1) Cytotoxicity in vitro; 1) survival fraction at beta-carotene concentration of 0.002, 0.02, 0.2 and 2 mg/ml were 0.69+/-0.07, 0.59+/-0.08, 0.08+/-0.008 and 0.02+/-0.006, respectively. 2) each survival fraction at 2, 4, 6 and 8 Gy in the 2 mg/ml of beta-carotene + X-irradiation group were 0.13+/-0.05, 0.03+/-0.005, 0.01+/-0.002 and 0.009+/-0.0008, respectively. But each survival fraction at same irradiation dose in the X- irradiation group were 0.66+/-0.05, 0.40+/-0.04, 0.11+/-0.01 and 0.03+/-0.006, respectively( p0.05). CONCLUSION: The contact of beta-caroten to FSaII cells showed mild cytotoxicity which was increased according to concentration. The cytotoxicity of combined beta-carotene with X-irradiation more increased than that of X-irradiation, additionaly. And there was significant difference of cytotoxicity between two groups. But there were no significant difference of the growth delay of fibrosarcoma between two groups.