Knowledge about prevention and control of chicken leukemia

1, chicken leukemia brief

Chicken leukemia is one of the diseases that cause a recessive infection in chickens caused by avian leukosis virus (ALV), but has a major economic impact. It can be vertically infected by the eggs, causing ALV to persist in the flock and spread from generation to generation; early horizontal infection; insect infection and vaccine contamination or needle infection during vaccination. Chicken ALV is divided into subgroups A, B, C, D, E and J. Only the E subgroup is an endogenous virus, which is usually pathogenic or has nothing to do with pathogenicity; other subtypes are exogenous viruses that are highly pathogenic. The purification of flock ALV is mainly to purify the exogenous virus. There are two major antigenic proteins in the virions of ALV: the envelope protein (gp85) and the major capsid protein (P27). Among them, gp85 is an antigen that distinguishes subgroups. Common J-subgroup infected chickens can be detected by Avian combined with Synbiotics (Chinese name, Xin Bax) company's avian leukemia J-subtype antibody kit; there is no significant difference in P27 protein between different subtypes. It can be used for ELISA method detection, such as detection of avian leukemia antigen detection kit produced by Synbiotics.

2, the harm to the chicken

Chicken leukemia causes tumor death in sick chickens: A, B, C, and D subpopulations are mainly lymphoma, including hemangioma and other types of cell tumors; J subgroup is mainly myeloid cell tumor, Including a higher proportion of hemangiomas and glandular enlargement or glandular gastritis; decreased performance; immunosuppression; vertical transmission.

3. Status of exogenous ALV infection in chickens in China

According to Professor Cui Zhizhong's research, the positive rates of ALV-AB subtype antibody, ALV-J subtype antibody and P27 antigen positive in Chinese white feather breeder flocks were 47.1%, 23.5% and 9.1%, respectively; The positive rates of the three breeds were 51.9%, 51.9%, and 90.4%, respectively. The positive rates of the three groups were 24.6%, 27.8%, and 60.7%, respectively. It can be seen that exogenous ALV infection in Chinese chickens is very serious.

In recent years, the number of hemangioma cases in laying hens has increased, which may be related to imported egg-type ancestral chicken poisoning, white feather broiler horizontal infection, vaccine pollution, and local varieties and inherent ALV.

4. Prevention and control of chicken leukemia

(1) Purification of breeding flocks: Thorough purification of the ancestral chickens; ancestors and the following chicken farms are required to introduce the Miao chickens as clean as possible. The core group adopts small group hatching and small group breeding; each sample is isolated from virus or P27 is detected, and all positive chickens and their same groups of chickens are eliminated; attenuated live vaccines are strictly selected; it is strictly forbidden to share hatcheries in different populations.

(2) Purification plan:
Option A (International Gold Standard) : A method currently in use at the Center for Poultry Disease Diagnosis and Prevention, University of Georgia, USA. All the core chickens were plasma-inoculated with DF-1 cells, and the P27 antigen was detected 9 days later. All the positive ones were eliminated, and two blood collections were performed at 68 days and 168 days respectively. In addition to the remaining core chickens of the remaining core group, all of the newly emerged chickens were tested for P27 in meconium and all positive chickens were eliminated. Repeatedly.

Option B:
A. Basic principle: According to the detection of P27 antigen in cloaca cotton swab and egg white, the positive ones are all eliminated.
B, specific procedures: hen and cock
18-20w and 21-22w, respectively, cotton swab detection P27;
23-25w: cotton swab test P27, initial egg white of the first 1-3 eggs detection P27;
40w: male hen cotton swab test P27, hen 2 eggs egg white detection P27;
43w hatched chicks Two chicks originally hatched by each hen, and the meconium cotton swab detected P27.
There are some differences in the sensitivity of kits from different companies. The most sensitive kit must be used when separating viruses from cell culture. Synbiotics' Avian Leukemia Antigen Test Kit detects 1.2 ng/ml of P27 antigen and is one of the best assay kits.

(3) Prevention of various horizontal infections and vaccine contamination

Prevent horizontal spread in hatcheries and transport boxes; avoid polyculture of different breeds of chickens in the same chicken farm or share the same hatchery; control insect spread; contamination of attenuated vaccines.

5. Synbotics Avian Leukemia Antigen and J Subtype Antibody Detection Kit

Synbiotics (Chinese name "Xin Bax") is a well-known company specializing in the production of animal disease ELISA test kits. The company's ProFLOK series of products - Avian Leukemia (ALV) ELISA antigen detection kit, can quickly detect P27 antigen in chicken serum and egg white; Avian leukemia J subtype (ALV-J) antibody detection kit, can quickly detect ALV-J antibody to chicken serum. The method has the characteristics of high sensitivity and strong specificity.

(1) The ALV antigen detection kit produced by the specific strong simbols only reacts with the sample containing the ALV antigen and does not react with other antigens infected; the ALV-J antibody detection kit only produces the ALV-J antigen. The antibody reacts and does not react with antibodies produced by various other avian infectious pathogen antigens. Both have excellent specificity and sensitivity, providing an effective, specific and reproducible test result.
(2) The sensitive high-simple Bacchus ALV antigen detection kit can detect P27 antigen as low as about 1.2 ng/ml, while the complement binding assay (COFAL) can only detect more than 4 ng/ml of P27 antigen, so the former It can better detect infected ALV in chicken flocks; Simmons ALV-J antibody detection kit can distinguish multiple ALV-J isolates under the premise of maintaining the same sensitivity as the virus neutralization test. Simmons and other brands of competitive ELISA kits were tested in parallel, and the coincidence rate of the results was 62%, while the results of Simmons were identical to those of the actual flocks infected with ALV-J. Has good sensitivity.
(3) The Simmons ALV antigen and J-subtype antibody detection kit has the following advantages:
The results are reliable and consistent; easy to use; certified by USDA (US Department of Agriculture); standardized reagents, strong detection specificity, high sensitivity, good repeatability; long effective period (up to 18 months); Powerful data management software; excellent technical service team.
(4) Analysis of test results