Mucosal or systemic administration of rE2 glycoprotein antigen loaded PLGA microspheres

We have evaluated the ability of recombinant E2 antigen, as a surfactant free formulation of poly (D,L-lactide-co-glycolide) (PLGA) microspheres, to elicit a systemic immune response after administration by mucosal routes (oral and nasal) in comparison to intramuscular route. The sequence encoding a truncated E2 glycoprotein of the classical swine fever virus (CSFV) was expressed in insect cells following infection with recombinant baculovirus, as a His-tagged recombinant antigen. The recombinant E2 glycoprotein (rE2) antigen was co-encapsulated with rabbit serum albumin (RSA) as a protein stabilizer. rE2/RSA loaded PLGA microspheres, with a mean diameter of 4 microm were obtained by a water in oil in water solvent extraction method (w/o/w). Rabbits were immunized with 10 microg of rE2 formulated in PLGA microspheres administrated by three different routes (oral, nasal and intramuscular). After 60 days, each rabbit in all three groups was challenge with 5 microg of rE2 glycoprotein solution by intradermal administration. Blood samples were collected weekly for 90 days and specific rE2 antigen antibodies measured. This work showed that rE2 antigen loaded microspheres was able to initiate an immune response. The intradermal challenge after nasal and oral administration had a clear boost effect on the systemic immune response. Moreover, the response after nasal administration was more intense and less variable than oral route. In conclusion, these data demonstrate a high potential of rE2 loaded PLGA microspheres for their use as a mucosal subunit vaccine.

Development of genetic tools for Lactobacillus sakei: disruption of the beta-galactosidase gene and use of lacZ as a reporter gene To study regulation of the putative copper ATPase, AtkB

Downstream from the ptsHI operon of Lactobacillus sakei, the genes atkY and atkB, organized in an operon, were observed. The two putative proteins, AtkB and AtkY, show sequence similarity to the Enterococcus hirae copper P-type ATPase, responsible for copper efflux, and its negative regulator. Characterization of AtkB as a copper P-type ATPase could not be demonstrated since an atkB mutant did not show any phenotype. Thus, another strategy was followed in order to investigate the transcriptional regulation of the atkYB locus, leading to the development of new genetic tools for L. sakei. A plasmid was constructed, the use of which allowed gene replacement at the lacLM locus in L. sakei by two successive crossovers. A strain deleted of the lacLM operon encoding the beta-galactosidase of L. sakei was constructed by this method, and the Escherichia coli lacZ gene could then be used as a reporter gene to investigate the regulation of atkYB. Results show that the atkYB operon is induced by small concentrations of CuSO(4) (30 to 40 microM) but not when CuSO(4) is omitted or added at higher concentrations.