| Avian leukosis virus(ALV)is a kind of retroviruses which can cause different tumor and immunosuppressive diseases in poultry.According to the characteristics of its envelope protein,ALV can be divided into 11 subgroups(A-K).Among them,ALV-A,B and J are endemic,and ALV-J is the most common in China.ALV-J infection mainly causes malignancy of chicken hematopoietic cells,myeloma,hemangioma and severe immunosuppression,which has caused huge economic losses to poultry industry globally.With the application of ALV eradication program in China,the infection and incidence rate of ALV-J in chicken flocks is being decreased significantly.ALV-K is a novel avian leukosis virus recently isolated and identified from domestic chicken breeds in China.Due to its weak replication activity,ALV-K infection in chicken flocks is not easy to be detected,which is challenging the current detection and purification technologies for ALV.In this study,an isolate of ALV-K was first isolated and identified from one chicken flock suspected with the infection of ALV in Nantong area.Then the epidemiological detection of ALV in Nantong area was carried out in 8 large-scale local ancestral chicken farms by using the detection kits for antibodies against ALV-A/B/J and p27 antigen of ALV.The eradication program of ALV in two strains of the breeder chicken for three generations was performed.1.Epidemiological investigation of ALV infection in NantongTo understand the infection status of ALV in Nantong area,in this study,the PCR detection and virus isolation was carried out for one chicken flock in Nantong area suspected with the infection of ALV.Then the epidemiological detection of ALV in Nantong area was performed in 8 large-scale local ancestral chicken farms by using the commercial ALV-A/B antibody kit,and kits for ALV-J antibody and the ALV antigen developed by the Key Laboratory of Animal Preventive Medicine of Yangzhou University.The results showed that an AVL-K isolate named NT181121 was efficiently isolated and identified from the suspected chicken flock.The positive rate for ALV-A/B antibody was 87.5%(7/8)in 8 chicken farms,that for each chicken farm was 4%(2/50),4%(2/50),0%(0/50),4%(2/50),2%(1/50),6%(3/50),12%(6/50)and 4%(2/50)respectively,and the overall individual positive rate is 4.5%(18/400).The positive rate for ALV-J antibody was 100%(8/8)in 8 chicken farms,that for each chicken farm was 20%,36%,14%,6%,50%,6%,22%and 26%respectively,and the overall individual positive rate is 22.5%(90/400).The positive rate for ALV antigen in blood was 100%(8/8)in 8 chicken farms,that for each chicken farm is 14%(7/50),22%(11/50),8%(4/50),24%(12/50),26%(13/50),10%(5/50),24%(12/50)and 18%(9/50)respectively,and the overall individual positive rate was 18.25%(73/400).All these data of exogenous ALV infection in the eight large-scale breeder chicken farms in Nantong area demonstrate that ALV infection is very common in Nantong.2.Preliminary eradication of ALV for two strains of breeders in NantongDue to the prevalence of ALV infection in some areas of Nantong,the eradication program of ALV in two local strains of breeders(code 3 and 6 respectively)in Nantong were performed with the gold standard protocol of ALV eradication.The results showed that the positive rate of virus isolation in cloacal swabs samples and whole blood samples of No.3 and No.6 breeders was decreased significantly after three generations of ALV detection and eradication.In breeders No.3,the positive rate of ALV p27 antigen in cloacal swabs samples was decreased from 38.4%(without eradication)to 4.7%,and that of viral isolation in anticoagulant blood was decreased from 11.2%(without eradication)to 1.46%.In breeders No.6,the positive rate of ALV p27 antigen in cloacal swabs samples was decreased from 19.8%(without eradication)to 6.3%,that of viral isolation in anticoagulant blood was decreased from 6.3%(without eradication)to 0.8%.All these data demonstrate that the eradication of ALV in the two local strains of breeders in Nantong area for three generations by using the above approaches was very efficient. |
PDF Full Text Request