Classical swine fever caused by Classical swine fever virus （CSFV） is a serious problem for swine industries in developing countries, which successful control of the disease have been relying on vaccination. However...Classical swine fever caused by Classical swine fever virus （CSFV） is a serious problem for swine industries in developing countries, which successful control of the disease have been relying on vaccination. However, classical swine fever still occurs in some immunized swine herds for various reasons. In this study, we conducted animal experiments to examine the influence of single or mixed infection with Porcine parvo virus （PPV）, Pseudorabies virus （PRV） and Porcine reproductive and respiratory syndrome virus （PRRSV） on the protective immunity induced by the Lapinized hog cholera virus （HCLV） vaccine and the pathogenicity of CSFV. In experiment 1, pigs were first inoculated with PPV, PRV or PRRSV, then immunized with HCLV, and finally challenged with a highly virulent CSFV Shimen strain. All of the pigs immunized with HCLV survived after the challenge, while all of the pigs in the non-immunized control group died after the challenge. The pigs in the group immunized with HCLV did not show any clinical symptoms of classical swine fever and were negative with CSFV after the challenge. The pigs infected with the non-CSFV before HCLV immunization did not display any clinical symptoms after the challenge with CSFV Shiman strain, but 11 of the 12 pigs were positive with CSFV. In experiment 2, pre-infections with PPV, PRV, and PRRSV were followed by inoculation with a low-virulence CSFV strain （CSFV 39）, and then the pigs were challenged with the CSFV Shimen strain. Infections by either PPV, PRV or PRRSV did not enhance the virulence of CSFV-39, but pigs infected by a mixture of the 3 viruses developed clinical symptoms after inoculation with CSFV-39. The mixed infection also increased mortality caused by the challenge with the CSFV Shimen strain. Together, these results showed PPV, PRV and PRRSV infections in pigs can reduce the efficacy of the HCLV vaccine and enhance the pathogenicity of CSFV, which may partly explain the immunization failure against CSFV in some swine herds.展开更多
The 5′ nonencoding region, p23 and p14 encoding region and E1 gene of hog cholera virus (HCV) strain C were amplified from total RNA extracted from HCV strain C infected rabbit spleen by reverse transcription and nes...The 5′ nonencoding region, p23 and p14 encoding region and E1 gene of hog cholera virus (HCV) strain C were amplified from total RNA extracted from HCV strain C infected rabbit spleen by reverse transcription and nested or half\_nested PCR. The PCR products were cloned into pGEM\|T vector. Nucleotide sequencing was performed using an ABI PRISM sequencing device; based on the incorporation of fluoresect labelled dideoxynuclotide teminators. The obtained sequences on 5′ noncoding region and part of p23 and p14 encoding region were compared with HCV strains Shimen and C sequenced in Moormann’s lab. The result showed that the homology between HCV strains C sequenced in this report and in Moormann’s lab was 99.19%, and the homology between HCV strains Shimen, the standard virulent HCV strain in China, and C sequenced in this report was 94.69%. It was also discovered that the base C at 244 of the genome of HCV strains Shimen and C sequenced in this report was absent at the genome of C strain sequenced in Moormann’s lab et al.展开更多
文摘Classical swine fever caused by Classical swine fever virus （CSFV） is a serious problem for swine industries in developing countries, which successful control of the disease have been relying on vaccination. However, classical swine fever still occurs in some immunized swine herds for various reasons. In this study, we conducted animal experiments to examine the influence of single or mixed infection with Porcine parvo virus （PPV）, Pseudorabies virus （PRV） and Porcine reproductive and respiratory syndrome virus （PRRSV） on the protective immunity induced by the Lapinized hog cholera virus （HCLV） vaccine and the pathogenicity of CSFV. In experiment 1, pigs were first inoculated with PPV, PRV or PRRSV, then immunized with HCLV, and finally challenged with a highly virulent CSFV Shimen strain. All of the pigs immunized with HCLV survived after the challenge, while all of the pigs in the non-immunized control group died after the challenge. The pigs in the group immunized with HCLV did not show any clinical symptoms of classical swine fever and were negative with CSFV after the challenge. The pigs infected with the non-CSFV before HCLV immunization did not display any clinical symptoms after the challenge with CSFV Shiman strain, but 11 of the 12 pigs were positive with CSFV. In experiment 2, pre-infections with PPV, PRV, and PRRSV were followed by inoculation with a low-virulence CSFV strain （CSFV 39）, and then the pigs were challenged with the CSFV Shimen strain. Infections by either PPV, PRV or PRRSV did not enhance the virulence of CSFV-39, but pigs infected by a mixture of the 3 viruses developed clinical symptoms after inoculation with CSFV-39. The mixed infection also increased mortality caused by the challenge with the CSFV Shimen strain. Together, these results showed PPV, PRV and PRRSV infections in pigs can reduce the efficacy of the HCLV vaccine and enhance the pathogenicity of CSFV, which may partly explain the immunization failure against CSFV in some swine herds.
文摘The 5′ nonencoding region, p23 and p14 encoding region and E1 gene of hog cholera virus (HCV) strain C were amplified from total RNA extracted from HCV strain C infected rabbit spleen by reverse transcription and nested or half\_nested PCR. The PCR products were cloned into pGEM\|T vector. Nucleotide sequencing was performed using an ABI PRISM sequencing device; based on the incorporation of fluoresect labelled dideoxynuclotide teminators. The obtained sequences on 5′ noncoding region and part of p23 and p14 encoding region were compared with HCV strains Shimen and C sequenced in Moormann’s lab. The result showed that the homology between HCV strains C sequenced in this report and in Moormann’s lab was 99.19%, and the homology between HCV strains Shimen, the standard virulent HCV strain in China, and C sequenced in this report was 94.69%. It was also discovered that the base C at 244 of the genome of HCV strains Shimen and C sequenced in this report was absent at the genome of C strain sequenced in Moormann’s lab et al.
