Classical swine fever (CSF), an acute and highly contagious disease of swine, is caused by classical swine fever virus. CSF is one of the most devastating diseases to the pig industry worldwide and results in serious economic losses. Currently prophylactic vaccination is still an important strategy for the control of CSF. Live attenuated vaccines (such as C-strain) are safe and effective. However, there are significant changes in the clinical features of CSF, displaying concurrent typical and atypical CSF, and simultaneous inapparent and persistent infections. Immunization failure has been reported frequently and it is difficult to distinguish between wild-type infected and vaccinated animals (DIVA). So there is an urgent need to develop more effective and safer DIVA or marker vaccines for the control of CSF. In this review, some of the most recent advances in new-type vaccines against CSF, including DNA vaccines, live virus-vectored vaccines, protein or peptide-based vaccines, gene-deleted vaccines and chimeric pestivirus-based vaccines, are reviewed and discussed.
Animals ; Classical Swine Fever ; prevention & control ; Classical swine fever virus ; Swine ; Vaccination ; veterinary ; Vaccines, Attenuated ; immunology ; Vaccines, DNA ; immunology ; Vaccines, Subunit ; immunology ; Viral Vaccines ; immunology

Advances in the field of xenotransplantation raise the intriguing possibility of using porcine red blood cells (pRBCs) as an alternative source for blood transfusion. Serologically, pRBCs share a number of characteristics with human red blood cells (RBCs), so pRBCs are considered the most likely donor for xenotransfusion. However, xenoantigens on porcine erythrocytes play major roles in antibody-mediated RBC destruction. Although the alphaGal epitope (Galalpha1, 3Galbeta1, 4GalNAc-R) is the major xenoantigen on porcine erythrocytes and is responsible for the binding of the majority of human natural antibodies, other non-alphaGal xenoantigens have been identified. The importance of these non-alphaGal xenoantigens in binding human natural antibodies and subsequently triggering immunological responses cannot be underestimated.
Animals ; Blood Group Antigens ; immunology ; Erythrocyte Transfusion ; methods ; Erythrocytes ; cytology ; immunology ; Humans ; Swine ; Transplantation, Heterologous ; immunology

E2 gene of classical swine fever virus (CSFV) was cloned into secretory pPIC9K Pichia pastoris expression vector. After being linearized by digestion, the vector was transformed into Pichia pastoris by electroporation to integrate with the genome, the transformants with high copies were screened by G418 and were induced to express with methonal. The results of SDS-PAGE and Western blot demonstrated that the supernatant of the induced P. pastoris culture contained protein E2. The results of the study on the immunological activity indicated that the protein E2 expressed in P. pastoris can elicit animal bodies to produce antibodies against protein E2.
Animals ; Antibodies, Viral ; immunology ; Antigens, Viral ; genetics ; immunology ; Classical swine fever virus ; genetics ; immunology ; Cloning, Molecular ; Gene Expression ; Pichia ; Rabbits ; Swine ; Viral Envelope Proteins ; genetics ; immunology

Classical Swine Fever Virus (CSFV) E2 protein eukaryotic expression plasmid pVAXE2 was constructed. The plasmid pVAXE2 was transformed into Salmonella choleraesuis C500 (S. C500) attenuated vaccine strain by electroporation to generate Salmonella choleraesuis engineering strain S. C500/pVAXE2. The characterization of S. C500/pVAXE2 in morphology, growth, biochemistry and serology indicated that it retained the same properties as its original strain S. C500 with exception of kanamycin resistance originated from the plasmid pVAXE2. The plasmid stable in the bacteria after 15 passages. Kunming mice and rabbits were vaccinated three times at two weeks interval with S. C500/pVAXE2 in oral and intramuscular routes at the dosage of 1 x 10(8) CFU for mice and 2 x 10(9) CFU for rabbits each time. The specific antibody response against CSFV and Salmonella choleraesuis was detected by ELISA. Two weeks after the third boost the immunized rabbits were challenged with 20 ID50 of hog cholera lapinized virus (HCLV), followed by a virulent strain of Salmonella choleraesuis two week later than HCLV challenge. The results showed that all immunized mice and rabbits produced significant antibodies against CSFV and Salmonella choleraesuis, and the immunized rabbits demonstrated the effective protection against the challenge of HCLV and virulent Salmonella choleraesuis. These results indicated the potential of developing multiplex swine DNA vaccine by using this bacteria as the vector.
Animals ; Classical Swine Fever ; immunology ; prevention & control ; virology ; Classical swine fever virus ; genetics ; immunology ; Mice ; Rabbits ; Salmonella arizonae ; genetics ; Swine ; Vaccines, DNA ; immunology ; Viral Envelope Proteins ; biosynthesis ; genetics ; immunology ; Viral Vaccines ; immunology

This study was aimed to explore impact of removal of cell membrane G alalpha1-3Gal beta1-4Glc NAc epitopes (called alpha-Gal) and chemical modification of other xenoantigen on bovine red blood cell (bRBC) and porcine red blood cell (pRBC) antigenicity and to compare their modified erythrocytes, in order to provide basis for development of human blood substitute with rich source, high safety and efficacy. bRBC and pRBC were subjected to both enzymatic removal of membrane alpha-Gal with recombinant coffee bean alpha-galactosidase (rC alpha-GalE) and covalent attachment of benzotriazole carbonate-linked methoxypolyethylene glycol (mPEG-BTC, MW = 20 kD). The effects of treatment were measured by hemagglutination, flow cytometric assay of IgG binding and clinical cross-match testing to human sera. The results showed that although alpha-galactosidase treatment reduced hemagglutination titers to levels similar to negative control, the combination of the treatments was most effective. Clinically used cross-match tests between bRBC, pRBC and human sera demonstrated increased compatibility. Bovine RBC were more robust than pRBC, and had less xenoantigens, and had longer half life than pRBC in vivo. These characteristics suggested that bRBCs were more suitable to investigation as an alternatives to hRBC in clinical transfusion than pRBC. These data suggested that strategies to remove or mask xenoantigens on bRBC reduce antigenicity sufficiently to allow in vitro cross-match compatibility to human sera, and therefore bRBC following modification may be considered as human blood substitute.
Animals ; Antigens, Heterophile ; immunology ; Blood Substitutes ; Cattle ; Disaccharides ; immunology ; Epitopes ; immunology ; Erythrocyte Membrane ; immunology ; Erythrocyte Transfusion ; methods ; Erythrocytes ; immunology ; metabolism ; Humans ; Swine ; alpha-Galactosidase ; immunology

OBJECTIVETo review the current status and progress on pig islet xenotransplantation.

DATA SOURCESData used in this review were mainly from English literature of Pubmed database. The search terms were "pig islet" and "xenotransplantation".

STUDY SELECTIONThe original articles and critical reviews selected were relevant to this review's theme.

RESULTSPigs are suggested to be an ideal candidate for obtaining available islet cells for transplantation. However, the potential clinical application of pig islet is still facing challenges including inadequate yield of high-quality functional islets and xenorejection of the transplants. The former can be overcome mainly by selection of a suitable pathogen-free source herd and the development of isolation and purification technology. While the feasibility of successful preclinical pig islet xenotranplantation provides insights in the possible mechanisms of xenogeneic immune recognition and rejection to overwhelm the latter. In addition, the achievement of long-term insulin independence in diabetic models by means of distinct islet products and novel immunotherapeutic strategies is promising.

CONCLUSIONSPig islet xenotransplantation is one of the prospective treatments to bridge the gap between the needs of transplantation in patients with diabetes and available islet cells. Nonetheless, further studies and efforts are needed to translate obtained findings into tangible applications.

Animals ; Graft Rejection ; immunology ; prevention & control ; Islets of Langerhans Transplantation ; immunology ; methods ; Swine ; Transplantation, Heterologous ; methods

To construct a recombinant adenovirus co-expressing the E2 protein of classical swine fever virus (CSFV) and the porcine interleukin 2 (pIL-2), the CSFV E2 gene and pIL-2 gene were amplified respectively from the plasmids pMD19-T-E2 and pMD19-T-pIL-2 by PCR. E2-pIL-2 fusion gene was obtained by using 5 consecutive glycine codons as a linker and cloned into the adenoviral shuttle plasmid AdTrack. The AdTrack-E2-pIL-2 was linearized and transformed into E. coli BJ5183 with the backbone plasmid AdEasy1. The resultant recombinant plasmid AdEasy-E2-pIL-2 was transfected into the 293 cells where the recombinant adenovirus rAd-E2-pIL-2 was produced. The immunogenicity of rAd-E2-pIL-2 was evaluated in rabbits. The results of RT-PCR and Western-blotting showed that rAd-E2-pIL-2 could carry and express E2 and pIL-2 proteins. The titer of the rAd-E2-pIL-2 was 10(8.12) PFU/mL. After immunized with rAd-E2pIL-2, The injected rabbits developed a high level of CSFV specific antibodies. Regular fever was not detected in the rAd-E2-pIL-2-immunized rabbits upon challenge with CSFV C stain, and specific lymphoproliferative responses to the CSFV was detected in the lymphocytes from the immunized rabbits. In conclusion, rAd-E2-pIL-2 was constructed successfully and it could be an attractive vaccine candidate against CSFV.
Adenoviridae ; genetics ; metabolism ; Animals ; Cell Line ; Classical swine fever virus ; genetics ; Humans ; Interleukin-2 ; genetics ; immunology ; Rabbits ; Swine ; Viral Proteins ; genetics ; immunology ; metabolism ; Viral Vaccines ; immunology

In 1990, it was reported that the naked DNA encoding an antigen (so-called DNA vaccine) transduced directly into the muscle is able to induce immune responses just like antigen inoculation. Since then, a number of DNA vaccines against different diseases have been developed and shown to induce different levels of specific humoral and/or cell-mediated immunity. Efforts have been made to develop effective DNA vaccines against classical swine fever (CSF). This review covered the following aspects in the development and application of CSF DNA vaccines: construction and evaluation, application of adjuvants, combination with other vaccines and the existing problems and solutions.
Adjuvants, Immunologic ; pharmacology ; Animals ; Classical Swine Fever ; prevention & control ; Swine ; Vaccines, DNA ; biosynthesis ; immunology ; Viral Envelope Proteins ; genetics ; immunology ; Viral Vaccines ; biosynthesis ; immunology

Porcine reproductive and respiratory syndrome virus (PRRSV) non-structural protein 7 (Nsp7) plays an important role in the induction of host humoral immune response and could serve as an ideal antigen for serological genotyping assay for PRRSV based on the significant difference in immunoreactivities of North American (NA) and European (EU) PRRSV Nsp7. In this study, Nsp7 of NA and EU PRRSVwas separately expressed and purified using prokaryotic expression system. The purified recombinant Nsp7 proteins reacted with serum antibodies against corresponding genotype PRRSV in Western blotting. However, nonspecific reaction of whole recombinant Nsp7 with antibodies against another genotype PRRSV was observed, indicating that whole NA PRRSV Nsp7 and EU PRRSV Nsp7 have similar antigenic epitopes and recombinant proteins could not be used for genotyping of antibodies against PRRSV. Based on the analysis of similar antigenic epitopes at the hydrophilic region of NA PRRSV Nsp7 and EU PRRSV Nsp7 by bioinformatics assessment, partial Nsp7 gene region deleted sequences encoding similar antigenic epitopes was constructed by fusion PCR. The recombinant truncated Nsp7 (NA-deltaNsp7 and EU-deltaNsp7, about 43 kDa) was expressed and the molecular weight was about 43 kDa. The results of Western blotting showed that NA-deltaNSP7 and EU-deltaNSP7 could be specifically recognized by positive serum to NA or EU PRRSV individually and nonspecific reaction was eliminated. This study provided a basis for further development of serological genotyping assay for North American and European genotype PRRSV infection.
Animals ; Genotype ; Porcine respiratory and reproductive syndrome virus ; classification ; genetics ; immunology ; Recombinant Proteins ; biosynthesis ; immunology ; Swine ; Viral Nonstructural Proteins ; biosynthesis ; immunology

The role of Mac-1 as a receptor for Bordetella bronchiseptica infection of alveolar macrophages (AMphi) was examined using 6 strains (2 ATCC and 4 pathogenic field isolates) to assess B. bronchiseptica binding, uptake and replication in primary porcine AMphi. All B. bronchiseptica strains were rapidly killed by porcine serum in a dose- and time-dependent manner. However, heat-inactivated porcine serum (HIS) did not demonstrate any bacterial-killing activity, suggesting that complement may have a direct killing activity. All field isolates were more resistant to direct complement-mediated B. bronchiseptica killing. The uptake of B. bronchiseptica into AMphi was inhibited approximately 50% by antiMac-1 monoclonal antibodies in the medium. However, B. bronchiseptica phagocytosed in the presence of serum or HIS was not altered by anti-Mac-1 antibodies although more bacteria were internalized by addition of serum or HIS. These data suggest that Mac-1 is a target for direct uptake of B. bronchiseptica via opsoninindependent binding. The phagocytosed B. bronchiseptica, either via direct or serum-mediated binding, were efficiently killed by AMphi within 10 hr postinfection. This demonstrates that Mac-1-mediated B. bronchiseptica uptake is a bacterial killing pathway not leading to productive infections in AMphi.
Animals ; Antibodies, Bacterial/blood/immunology ; Bordetella bronchiseptica/*immunology ; Macrophage-1 Antigen/*immunology ; Macrophages, Alveolar/*immunology ; Phagocytosis ; Protein Binding ; Swine/*immunology/*microbiology