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

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

To investigate the effects of classical swine fever virus (CSFV) virulent strain Shimen (SM) infection on piglets peripheral blood leucocytes, the 60-days weanling piglets were infected with the shinen strain and the peripheral blood samples of the piglets were collected to analyze the kinetics of the CSEV nucleic acid, the peripheral blood leucocytes subpopulation and SLA molecule expression on the peripheral blood leukocytes. The results showed that the piglets rectal temperature increased 48 hours after intramuscular injection of CSFV SM strain, the CSFV nucleic acid was detected in the peripheral blood at 2DPI, the content of CSFV nucleic acid increased and up-regulated to a peak at 6DPI as 10 (4.84 +/- 0.98 times as 2DPI. The amount of WBC, LYM and PLT significantly decreased, where in the amount of WBC decreased to 65.87% at 1DPI and 50% at 2DPI respectively; the amount of LYM decreased to 70.68%, 47.88% and 23.29% at 1DPI, 2DPI, and 3DPI, respectively; the amount of PLT decreased day by day and to 34.59% at 6DPI; the amount of NK, gammadeltaT, Tc, Th, CD3+ CD4+ CD8+ and CD3- CD4- CD8- cells decreased after infection; 78.49% of NK cells decreased at 1DPI and then there was no significant change from 2DPI to 6DPI. The amount of gammadeltaT, Tc, CD4- CD8- CD3-,CD4+ CD8+ CD3+ cells decreased to 41.74%, 43.83%, 15.87%, and 32.96% at 3DPI, respectively, However, the amount of T helper cells decreased continually to 42.95% at 6DPI; the amount of SLA I positive lymphocytes decreased significantly and the amount of SLA I positive CD3 cells decreased to 23.07% and 15.38% at 1DPI and 2DPI respectively; the SLA I positive granulocytes increased continually from 92.20% at 1DPI to 98.30% at 3DPI; the amount of CD3 SLA II + cells in lymphocytes decreased from 1.38% at 1DPI to 0.22% at 2DPI, while the SLA II + granulocytes increased continually to a peak at 3DPI and 53.76% of granulocytes expressed the SLA II molecule, but the percentage of the granulocytes expressing SLA II molecules decreased to 12.54% and 4.06% at 4DPI and 5DPI respectively. The study indicated that the CSFV SM strain infection could escape the immune surveillance and cause immunosuppression through inhibiting the host's innate antiviral immunity and the SLA molecule expression to affect the antigen presentation.
Animals ; Cells, Cultured ; Classical Swine Fever ; genetics ; immunology ; virology ; Classical swine fever virus ; pathogenicity ; physiology ; Gene Expression ; Histocompatibility Antigens Class I ; genetics ; immunology ; Histocompatibility Antigens Class II ; Leukocyte Count ; Leukocytes ; immunology ; virology ; Random Allocation ; Swine ; Virulence

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

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

Classical swine fever (CSF) is a contagious swine disease charactered by hemorrhagic fever and leukopenia,usually leading to substantial economic losses. To obtain a insight of leucopenia caused by CSFV infection, DNA microarray analyses of peripheral blood leucocytes (PBL) of the infected pigs was performed. Three health pigs were inoculated with a lethal dose of CSFV Shimen strain and their PBLs were isolated when the onset of typical clinical signs and then subjected to total RNA extraction followed by microarray analysis with Affymetrix Porcine Genome Array GeneChips. The results showed that the significant differences were observed in cellular apoptotic genes expression at 7 days post-infection (p. i.). The changes of the genes expression were confirmed by real time RT-PCR of some selected apoptosis-related genes. This study provided a valuable information for further investigating the molecular mechanism of apoptosis caused by CSFV infection.
Animals ; Apoptosis ; Cells, Cultured ; Classical Swine Fever ; genetics ; immunology ; virology ; Classical swine fever virus ; immunology ; physiology ; Gene Expression Profiling ; Leukocytes, Mononuclear ; cytology ; immunology ; virology ; Molecular Sequence Data ; Oligonucleotide Array Sequence Analysis ; Sus scrofa

We have shown previously that a Semliki Forest virus (SFV) replicon vectored DNA vaccine (pSFV1CS-E2) expressing the E2 glycoprotein of classical swine fever virus (CSFV) conferred full protection for pigs immunized three times with 600 microg of the vaccine. This study aims to evaluate the efficacy of the DNA vaccine with lower dosage and fewer inoculations. Pigs were immunized twice with 100 microg pSFV1CS-E2 (n = 5) or control plasmid pSFV1CS (n = 3), respectively. Pigs immunized with pSFV1CS-E2 developed high titers of specific neutralizing antibodies against CSFV after the booster, and the antibody titers increased rapidly upon challenge. The immunized animals showed no clinical symptoms except short-term fever and low-level viremia, whereas the control pigs immunized with the control plasmid produced no detectable antibody before challenge and showed obvious clinical signs following challenge, and 2 pigs died on 10 or 11 days post-challenge. All control animals developed extended viremia as detected by nested RT-PCR and real-time RT-PCR. Severe pathologic lesions typical of CSFV infection were observed at necropsy. We conclude that the alphavirus replicon-vectored DNA-based vaccine can be potential marker vaccine against CSFV.
Animals ; Antibodies, Neutralizing ; blood ; immunology ; Antibodies, Viral ; blood ; immunology ; Body Temperature ; immunology ; Classical Swine Fever ; blood ; immunology ; prevention & control ; Classical swine fever virus ; genetics ; immunology ; Genetic Vectors ; genetics ; Immunization ; Plasmids ; genetics ; Replicon ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Semliki forest virus ; genetics ; Swine ; virology ; Time Factors ; Vaccines, DNA ; administration & dosage ; genetics ; immunology ; Viral Envelope Proteins ; genetics ; immunology ; Viremia ; genetics ; immunology

We have previously evaluated a Semliki Forest virus (SFV) replicon vectored DNA vaccine (pSFV1CS2-E2) and a recombinant adenovirus (rAdV-E2) expressing the E2 glycoprotein of classical swine fever virus (CSFV) in pigs. The results showed that the immunized pigs were protected from virulent challenge, but few pigs showed short-term fever and occasional pathological changes following virulent challenge. To enhance the immunogenecity of the vaccines, we tried a prime-boost vaccination strategy using a combination of prime with pSFV1CS2-E2 followed by boost with rAdV-E2. The results showed that all the immunized pigs developed high-level CSFV-specific antibodies following prime-boost immunization. When challenged with virulent CSFV, the immunized pigs (n = 5) from the heterologous boost group showed no clinical symptoms, and CSFV RNA was not detected following challenge, whereas one of five pigs from the homologous boost group developed short-term fever and CSFV RNA was detected. This demonstrates that the heterologous prime-boost vaccination regime has the potential to prevent against virulent challenge.
Adenoviridae ; genetics ; metabolism ; Adenovirus E2 Proteins ; genetics ; immunology ; Animals ; Classical Swine Fever ; immunology ; prevention & control ; Classical swine fever virus ; genetics ; immunology ; Genetic Vectors ; Immunization, Secondary ; Replicon ; genetics ; Semliki forest virus ; genetics ; metabolism ; Swine ; Vaccines, DNA ; immunology ; Viral Envelope Proteins ; genetics ; metabolism ; Viral Vaccines ; immunology

The CSFV E0 gene was amplified from the plasmid pMD18-T-E0 by PCR and cloned into the FPV-P11 and FPV-pSY. The identified recombinant DNA was transfected into chicken embryo fibroblasts (CEF) to package Fowlpox virus. E0 gene was confirmed to be integrated into the genome of recombinant Fowlpox virus by PCR, and Western blot was employed for detection of E0 expression in the chicken embryo fibroblasts infected with recombinant Fowlpox virus . The results of ELISA showed that systemic immune response to CSFV could be induced effectively after the mice were immunized three times with recombinant Fowlpox virus through celiac route, the titer of antibody was 1 : 4096. The protection experiment showed that 75% of piglets immunized three times with recombinant Fowlpox virus were survived, indicating that the recombinant Fowlpox virus was effective. This paper lays foundation for the study of CSFV live vector vaccine.
Animals ; Blotting, Western ; Chick Embryo ; Classical swine fever virus ; genetics ; immunology ; Enzyme-Linked Immunosorbent Assay ; Female ; Fowlpox virus ; genetics ; Mice ; Mice, Inbred BALB C ; Polymerase Chain Reaction ; Swine ; Vaccines, Synthetic ; immunology ; Viral Envelope Proteins ; genetics ; immunology ; Viral Vaccines ; immunology

To determine the immune responses in pigs to hog cholera virus after treatment with an ionized alkali mineral complex (IAMC), 40 healthy pigs (28-32 days old) from a commercial swine farm were purchased and housed into 4 groups (n=10 each). All pigs were vaccinated intramuscularly (1 ml) with an attenuated live hog cholera virus (HCV, LOM strain) at 28-32 days old and challenged with a virulent hog cholera virus at 8 weeks after vaccination. Each group was treated with PowerFeelTM sprayed diet as 0.05% (w/w) in a final concentration (T-1, n=10), a diet mixed with SuperFeedTM as 3% (w/w) in a final concentration (T-2, n=10), or a diluted PowerFeelTM solution (1:500, v/v) as drinking water (T-3, n=10), respectively. A group (n=10) served as a non-treated control. Proportions of expressing CD2+ and CD8+ cells increased significantly (p<, 0.05) at 8-week post-application. Mean antibody titers of each group against HCV gradually increased to higher levels after vaccination and with challenge of the virulent virus. In conclusion, the IAMC-treated diets can be helpful for the improvement of growth in pigs with proper vaccination program, while the IAMC-treated diets have no effects on the clinical protection against hog cholera.
Alkalies/immunology/*pharmacology ; Animals ; Antibodies, Viral/blood ; Classical Swine Fever/*immunology/prevention & control ; Classical swine fever virus/*immunology ; Flow Cytometry/veterinary ; Fluorescent Antibody Technique, Indirect/veterinary ; HLA Antigens/immunology ; Minerals/immunology/*pharmacology ; Swine ; Vaccination/*veterinary ; Vaccines, Attenuated/immunology ; Viral Vaccines/*immunology