| Avian leukemia is caused by the avian leukemia viras,a variety of infectious diseases of poultry collectively,The virus is a single-stranded RNA retrovirus,has been found in 10 subgroups,can naturally infect the poultry flocks of ALV only A?E and J subgroups,several other subtype only infected poultry or wild birds.Which in addition to E subtypes for the endogenous virus,the other are exogenous virus.Exogenous ALV has a strong pathogenicity,especially AB and J subtypes ALV prevalence of the most common,the development of China's poultry industry is also the greatest harm.There are four main causes of economic loss caused by avian leukemia:the production of tumors,leading to the death of chickens;non-tumor syndrome,manifested as changes in production performance,such as delayed sexual maturity,laying hens decreased egg weight,Fertilization rate and hatching rate decreased,which seriously affected the production.Avian leukemia infection,can cause chicken immune suppression,will be secondary to IBD,MD,CIA and other immunosuppressive diseases,resulting in more serious losses can be transmitted to the next generation of vertical chickens,affecting the quality of chicks.In recent years by the poultry leukemia caused by the death of chickens and eliminated the direct economic losses are increasing year by year.Yang Feng and other collected in all regions of Shandong Province and the introduction of major strains of local breed of chicken serum,cotton swab samples detection.The results showed that the positive rate of P27 antigen was 19.36%,the positive rate of ALV-A/B antibody was 9.29%,and the positive rate of ALV-J antibody was 5.18%.Bei and others investigated the prevalence of avian leukemia virus(ALV)in Jiangsu province and Anhui province showed that ALV infection was not only present in the breeder chickens,but also showed high level of antibody.Zhang Miaojie and others detected in four provinces in 115 imported:flocks of cloacal swabs for p27 antigen detection and serum J antibody,A/B antibody detection results show that China's imports of breed flocks in varying degrees of ALV-J subgroup,ALV-A/B subgroup infection,J antibody positive rate is generally higher than A/B antibody positive rate,and J antibody positive rate of broiler breed is higher than that of laying hens.In addition,the survey results also showed that the early laying of chickens p27 antigen positive rate and J antibody positive rate is higher.Indicating that there are many areas of ALV infection.As there is no avian leukemia commercial vaccine and special treatment drugs,the current control AB and J subtype ALV and other exogenous avian leukemia is the most effective means of detection and elimination of positive flocks to achieve the purpose of purifying the disease.In the "medium and long-term animal disease prevention and control program in Tianjin(2010-2020)" will be the priority of the prevention and treatment of avian leukemia disease,as the focus of purification poultry farm disease.It is the necessary measure to develop the ALV detection and purification program and to carry out the purification of ALV in poultry flocks.To understand the prevalence of Avian Leukosis(AL)in Tianjin,2024 serum samples and 2030 cloacal swabs were collected from 8 parents breeding farms in Tianjin.ALV-J,ALV-AB antibody and P27 antigen were detected by ELISA kit.The results showed that the antibody positive rate of AB and J subgroup was 4.25%and 11.12%,respectively,which was significantly higher than that of ALV-AB antibody positive rate and 10.74%of P27 antigen,the data showed Tianjin city breeder poultry leukemia infection in general.Fluorescent RT-PCR was used to detect the samples of clinically suspected leukemia chickens in Tianjin chicken fanns and their surroxmding chicken farms.The results showed that ALV-J subgroup was the most common subtype of avian leukemia in clinical cases in Tianjin,threatening the development of poultry industry in our city. |
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