ABSTRACT
Tissue samples of Fabricius' bursa collected from Nanning, Yulin, Beihai and Wuzhou in the provinces of Guangxi in China during the years of 2000-2007, were detected by a established reverse transcriptase polymerase chain reaction (RT-PCR) technique for IBDV. Viral isolation was performed on the positive samples by chicken embryo inoculation via chorio-allantoic membrane (CAM). Results showed that 27 isolates of IBDV were obtained. A set of primers were designed to amplify the vVP2 of 27 isolates by RT-PCR and the PCR products were sequenced. The sequences of all the isolates and reference viruses were analyzed and compared, and their phylogenetic trees were constructed based on the nucleotide sequences. The results indicated that isolate BH11, TZ(3), 050222, YL051, NN0603, NN0611and QX0602 etc, altogether 17 isolates, which accounted for 62.96 percent of total isolates, were identified to be very virulent IBDV (vvIBDV) and have the highest homology to vvIBDV reference strains. In the phylogenetic analysis, they are divided into 3 groups and have a long distance to commonly used vaccine stains. Isolate NN040124 and YL052 were identified as intermediate-plus virulent strains and showed a highest homology to classical strains of 52-70 and STC. 8 isolates of YLZF2, 040131 etc were identified as attenuated vaccine strains and showed a highest homology to classical strain of CU1. The results from the study demonstrated that the viruses prevailing in chickens in these 4 regions in Guangxi province in the recently 7 years were vvIBDV and their origins were complex. The antigenicity of some isolates may have been drifted.
Subject(s)
Animals , Amino Acid Sequence , Birnaviridae Infections , Epidemiology , Virology , Chickens , China , Epidemiology , Infectious bursal disease virus , Chemistry , Classification , Genetics , Molecular Epidemiology , Molecular Sequence Data , Phylogeny , Poultry Diseases , Epidemiology , Virology , Sequence Alignment , Viral Proteins , Chemistry , GeneticsABSTRACT
A transfer plasmid vector pUC18-US10-VP2 was first constructed by inserting the gene of the enhancer green fluorescent protein(eGFP) fused to the VP2 gene of very virulent Infectious bursal disease virus (IBDV) JS strain into the US10 fragment of the Marek's disease virus (MDV) CV1988/Rispens. The recombinant virus, designated as rMDV, was developed by co-transfecting CEF with the transfer plasmid vector and simultaneously infecting with the CVI988/Rispens virus. The PCR and IFA results indicated that the rMDV is stable after 31 passages. Chickens vaccinated with rMDV were protected from challenge with 100LD50 of IBDV JS. The protection ratio of the chickens vaccinated with the 1000PFU, 2000PFU, 5000PFU of the rMDV were 50%, 60%, and 80% respectively. It is interesting that the average histopathology BF lesion scores of chicken group immunized with 5000PFU of rMDV by one-time vaccination was close to that of chicken group vaccinated with IBDV live vaccine NF8 strain for twice (2.0/1.5). There is no difference in protection between the groups (P > 0.05) but significent difference between groups immunized with 5000 PFU of rMDV and with normal MDV. This demonstrated that rMDV expressing VP2 fusion protein was effective vaccine against IBDV in SPF chickens.
Subject(s)
Animals , Birnaviridae Infections , Chickens , Genetic Vectors , Green Fluorescent Proteins , Genetics , Infectious bursal disease virus , Genetics , Allergy and Immunology , Mardivirus , Genetics , Metabolism , Recombinant Fusion Proteins , Genetics , Allergy and Immunology , Recombination, Genetic , Transfection , Vaccination , Vaccines, DNA , Genetics , Allergy and Immunology , Viral Structural Proteins , Genetics , Allergy and Immunology , Viral Vaccines , Genetics , Allergy and ImmunologyABSTRACT
The envelope gene of ADOL-4817 strain of avian leukosis viru s subgroup J (ALV-J) was amplified by polymerase chain reaction （PCR） and clo ned into TA vector. The sequence analysis results showed that the envelope gene is composed of 1?746 bp, 1?554 bp of which could be translated into 517 amino acids for gp85 and gp37. The molecular weight of envelope protein is 57.7kD. T here are 15 potential glycosylation sites in the envelope protein, 13 of which i s located in gp85. Analysis of sequences of envelope gene indicate that ADOL -4817 showed high degree of sequence identity to other ALV-J strains, and m ost close ly related to the like-envelope gene of endogenous virus EAV-HP but divergent from these of other ALV subgroup A-E . These data support the hypothesis that envelope gene of avian leukosis virus subgroup J maybe acquired by recombination with expressed sequences.