Evaluation on the efficacy and immunogenicity of recombinant DNA plasmids expressing S gene from porcine epidemic diarrhea virus and VP7 gene from porcine rotavirus.

Porcine rotavirus (PoRV) and porcine epidemic diarrhea virus (PEDV) usually co-infect pigs in modern large-scale piggery, which both can cause severe diarrhea in newborn piglets and lead to significant economic losses to the pig industry. The VP7 protein is the main coat protein of PoRV, and the S protein is the main structural protein of PEDV, which are capable of inducing neutralizing antibodies in vivo. In this study, a DNA vaccine pPI-2.EGFP.VP7.S co-expressing VP7 protein of PoRV and S protein of PEDV was constructed. Six 8-week-old mice were immunized with the recombinant plasmid pPI-2.EGFP.VP7.S. The high humoral immune responses (virus specific antibody) and cellular immune responses (IFN-γ, IL-4, and spleen lymphocyte proliferation) were evaluated. The immune effect through intramuscular injection increased with plasmid dose when compared with subcutaneous injection. The immune-enhancing effect of IFN-α adjuvant was excellent compared with pig spleen transfer factor and IL-12 adjuvant. These results demonstrated that pPI-2.EGFP.VP7.S possess the immunological functions of the VP7 proteins of PoRV and S proteins of PEDV, indicating that pPI-2.EGFP.VP7.S is a candidate vaccine for porcine rotaviral infection (PoR) and porcine epidemic diarrhea (PED).

Microencapsulation of a synthetic peptide epitope for HTLV-1 in biodegradable poly(D,L-lactide-co-glycolide) microspheres using a novel encapsulation technique.

A novel procedure has been developed for the encapsulation of peptide antigens in poly(lactide-co-glycolide) (PLGA) microspheres, which employs trifluoro-acetic acid (TFA) as a carrier solvent for both the polymer and antigen. The antigen/polymer solution is emulsified in mineral oil containing sorbitan trioleate (Span 85) as an emulsifier and a low level of cottonseed oil to extract the TFA. Fluoresceinisothiocyanate-labelled bovine serum albumin (FITC-BSA) was used as a model antigen to characterize the microencapsulation. Microspheres were of the desired size (<10 microm) for targeting to antigen-presenting cells, and released the model antigen slowly after an initial burst release (11%) in PBS/0.02% Tween 80 at 37 degrees C. Subsequently, a potential peptide vaccine, designated MVFMF2, for the human T-lymphotropic virus type 1 (HTLV-1 ) was encapsulated at 4.7% loading using the novel oil-in-oil method. In vivo immune responses were examined in rabbits immunized with (i) encapsulated MVFMF2 together with encapsulated adjuvant (N-acetyl-glucosamine-3yl-acetyl-L-alanyl-D-isoglutamine, nor-MDP, (ii) encapsulated MVFMF2 without adjuvant, and (iii) free peptide with adjuvant. Inoculation of the encapsulated peptide produced an antibody response similar to that of the free peptide emulsified in adjuvant. Moreover, the elevated immune response elicited by the encapsulated peptide was observed without multiple booster immunizations and irrespective of whether an adjuvant was used. Additionally, the antibodies raised against both free and encapsulated MVFMF2 had similar affinities, as judged by competitive enzyme-linked immunosorbant assay (ELISA), indicating that the encapsulated peptide retained a significant fraction of its epitopes. Hence, these results demonstrate that peptide vaccines can be encapsulated in PLGA microspheres using a common carrier solvent for both the peptide and polymer, which produces a desirable immune response in the absence of an adjuvant.