The Establishment And Application Of PCR Technique For Diagnosis Of Chicken Infectious Anemia And Four Other Immunosuppressive Diseases

Chicken infectious anemia (CIA) is caused by chicken infectious anemia virus (CIAV). CIAV directly damages immune organs or tissues of chickens and causes aplastic anemia, generalized lymphoid atrophy and immunosuppression. The affected chickens are more susceptible to the infections of other pathogens. The severity of economic losses depends on the occurrences of secondary infections caused by other pathogens in the subsequence of immunosuppresion. The genome of CIAV encode three proteins: VP1, VP2 and VP3. VP3 also named apoptin, is the only known pathogenic factor of CIAV. A set of primers was designed to amplify the complete VP3 gene sequence and partial sequence of VP1 and VP2 gene for the development of a polymerase chain reaction (PCR)-based technique applied on detection of CIAV. Therefore, it is necessary to develop a rapid diagnostic technique for CIAV detection, CIA epidemiologic investigation, co-infections analysis of CIAV and other immunosuppressive virus, and further research on this area. A multiplex PCR technique was also developed for the detections on chicken infectious anemia virus(CIAV), marek's disease(MDV), reticuloendotheliosis(REV), and avian leucosis(ALV) co-infections. The method of DNA extraction was improved in this experiment. The whole diagnostic procedure, from sampling to the final conclusion, was completed within 5 hours, which spent 8 hours in the past.The developed multiplex PCR detection method was used during 2003/09– 2005/03. 185 chickens from 65 flocks were detected. The epidemiologic investigation showed that CIAV was ubiquitous in Anhui province, accounted for 25.95%(48/185) of chickens detected. The results showed that the detection rate was different among ages and species. The detection rate was high within 30 days. And three-yellow-chicken broilers gained the highest detection rate. The results of detections of different organs showed that bone marrow gained the highest detection rate.All samples were also detected for MDV, REV and ALV, and IBDV. The results showed that the co-infections rate of CIAV and other viruses was totally 22.32%(45/185). Infections of CIAV may increase the infection probability of oncogenic viruses.The results of the epidemiologic investigation indicated that immunosuppressive diseases are popular in the commercial chickens in Anhui province and are associated with the complexity of diseases and heavy losses in the industry.