Studies On The Biological Characteristics Of Recombinant Marek's Disease Virus Field Strain With REV-LTR

In recent years, some fowls disclose higher tumorigenesis for chickens viccinated against Marek's disease CVI988/Rispens .so scholar of exterior and interior suspected whether or not occurrence the higher pathogenicity of wild strain MDV which breakthrough this vaccine of protection.Zhangzhi isolated A recombinant Marek's disease virus field strain with REV-LTR of GX0101 from fowl group which tumorigenic in 2001. In order to disclose the failure of immune whether or not concerned with the pathogenicity enhance of this popular strain .Zhangzhi(2004)and Zhuang guoqing(2006) did artificial infextation experiment, indicated the pathogenicity of GX0101 highter than the GA,this research adopt mortality and tumor rates of GX0101 were 28.6% and 7.1% for SPF chickens viccinated against Marek's disease virus. Mortality and tumor rates of vvMd5 were 63.1% and 19.0% in the same viccinated SPF chickens. Mortality and tumor rates of GX0101 were lower than that of vvMd5. However, horizontal transmission ability of GX0101 was stronger than that of Md5. After 28 days challenged by GX0101, MDV was detected in 6 of 15 samples. After 35 days challenged by vvMd5, MDV was detected in 2 of 14 samples. Horizontal transmission ability of MDV isolates was not necessarily parallel to their pathogenicity.It is suggesting that the increased horizontal transmission may be one of selective competitive advantages. Such advantages may help recombinant viruses with the LTR-insert become more and more popular gradually in chicken flocks. This expenment compared the application in animal experiment between dot blot hybridization and agar diffusion reactionanimal experiment, the result indicated the virus can be detected from feather by dot blot hybridization after 10 days challenged, after 14days challenged can be detected by agar diffusion reaction, the highest detection rate of dot blot hybridization is 100%, but the the highest detection rate of agar diffusion reaction is 80%. The detection rate of dot blot hybridization was highter than the agar diffusion reaction. The sensitivity of dot blot hybridization was 1pg DNA, the detection of dot blot hybridization was fast, simple ,precise to a devil of sample. the dot blot hybridization can be trate as a utility means in detect MDV. Accordingly, dot blot hybridization has widely use in practical parturition.In order to imitate and pursuit retrovirus with marek's disease virus abiogenetic gene recombination in chincken 's vivo. To amplify and clone the integrated REV LTR with MDV sequence at the junction,4 primersfrom REV LTR and 7 primers from MDV genome fragment with REV LTR insertion hotpoint were synthesized and 28(4x7)pairs of primers(one from REV and another from MDVfor each pair)were used in PCR while the genomic DNA of both strains were used as the emplates. And we designed 30 pairs (one from REV and another from MDVfor each pair)were used in PCR while the genomic DNA of both strains were used as the emplates.of primers recombinated MDV which integrated the gene order of retrovirus.this expenment artificial coinfection with MDV and REV or ALV, when continue the 17th generation , can not isolate the re- combinate virus , the probability of two virus recombinated was very tiny, But,it is easily to isolate recombinated wild strain ,this expenment demonstrate the GX0101 under the long-standing selection.This research disclose , the horizontal transmission of recombinant Marek's disease virus field strain with REV-LTR of GX0101 highter than the rMD5 ,...