Infection Situation And Molecular Epidemiology Of Aleutian Disease In Ranch-raised Minks

38, 42 and 30 sera and tissue samples of minks pelted were obtained randomly, from Shan Dong, Liao Ning and Hei Longjiang provinces respectively in the period of pelting season, and used for detection of ADV infection. The ADV infection in these minks was investigated by detecting these samples with the methods of CEP and PCR separately. The infection ratio of ADV obtained through the two methods were 50.0%, 42.8%, 66.67% and 63.16%, 54.76%, 86.67%. The data of ADV infection ratio obtained with both of the methods could show that a high ratio of infection existed in the herd of ranch-raised minks in our country, although different ratio were showed between the two methods. And at the same time, the difference between two results also can indicate the error of CIEP method when it is used for AD detection.Reproduction situation of the ADV-positive female Minks determined by PCR was observed continuously. ADV infection of the kits born by the AD\-positive female Minks in the period of separation was also detected by PCR. The conclusion obtained included: 1) Compared with the control group, the number of the newborn kits in experimental group was reduced, and number of the dead fetuses and abnormal developed kits was much more in experimental group; 2) the percentage of ADV DNA positive in the newborn kits of experimental group was 100% detected by PCR.In the epidemiology study for AD, the work we had completed could be divided into two aspects.First, 16 isolates of ADV were obtained from Shan Dong, Liao Ning and Hei Longjiang provinces, the partial gene fragments which included hypervariable region were amplified by PCR, cloned and sequenced. The comparison of the sequences of the 16 isolates with that of the ADV-G, ADV-Utah1 and ADV-K, etc, which are representative isolates in foreign countries, had been completed by the nucleotide analysis software. Based on the comparison results, genotype differentiation of the 16 ADV isolates of our country and genetic and evolution relationship between the 16 isolates and the foreign isolates both were discussed, and the conclusion obtained included: Firstly, the genotypes for most ADV isolates of our countiy could be determined to be as II or III types. The closed relationship exists between domestic ADV isolates and foreign ones, and the probability that domestic AD was introduced from foreign countries is very high. Secondly, the ADV isolates we obtained had a high genetic diversity. ADV-DL1 and ADV-DL2 both had nucleotides lost. ADV-DL5 had obvious differences to foreign isolates. They may be the new types of ADV because of they have so obvious differences compared with foreign isolates in the gene sequences.Second, the nucleotide fragments much closely related to pathology in VP2 gene of ADV-DL1, ADV-DL2 and ADV-DL5 isolates were amplified by PCR, cloned and sequenced. The comparison of the sequences between the 3 ADV isolates and the foreign referential representative strains had also been completed. The results obtained showed that: the total variety was not very obvious in thegene sequences of the region that closely related to pathogenicity between ADV-DL1, ADV-DL2, ADV-DL5 isolates and foreign ones, the sequences homology was between 93.6%-96.0%. In the predicted amino-acid sequences from the gene sequences, the 3 ADV isolates all had specific amino acid mutations. The number of the mutations for ADV-DL1 and ADV-DL2 were less (5 and 6 sites respectively), and the mutation shouldn't cause obviously influence on the configuration of theirs structure protein VP2 on the basis of physical and chemical traits of the mutation amino acids. However, ADV-DL5 isolate owned more amino acid mutations than ADV-DL1 and ADV-DL2, the number of the mutation sites is 10, and some of the 10 mutation sites should have intensive influence on configuration of VP2 protein usually. Furthermore, the change on the configuration of the structure protein VP2 could do effect on pathogenicity of ADV. So, it will increase the possibility that ADV-DL5 is a peculiar ADV isolates in our country combined with the research conclude of the first part. In addition, it is an interested discovery that the predicted amino acid sequences of ADV-DL5, ADV-DL1 and ADV-Pullman, which are related to pathogenicity of ADV, owned 3-4 same amino acids that are different from other foreign pathogenic isolates.