The Development Of PCR Diagnostic Technique And Epidemiologic Investigation Of Chicken Infectious Anemia In Guangxi

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. Therefore, it is necessary to develop a rapid diagnostic technique for detection, epidemiologic investigation and further research of CIAV , and analyse co-infections of CIAV and other immunosuppressive virus.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 whole VP3 gene and parts of VP1 and VP2 gene for the development of a polymerase chain reaction (PCR)-based technique for detection of CIAV. A multiplex PCR technique was also developed for the detections of CIAV, MDV, REV and ALV co-infections. The whole diagnostic procedure, from sampling to the final conclusion, was finished within five hours by the modification of the DNA extraction.514 chickens from 108 flocks were detected by using the developed multiplex PCR during 2002/09 - 2004/04. The epidemiologic investigation showed that CIAV was ubiquitous in Guangxi, accounted for 72.22%(78/108) of flocks and 29.96%(154/514) of chickens detected. The results of detection of different ages and chicken varieties suggested that the detection rate of three-yellow-chicken broilers was highest. 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 with the chickens within 60 days old. The results showed the co-infections rate of CIAV and other viruses was totally 48.05%(74/154). Infections of CIAV may increase the infection opportunity of oncogenic viruses.The results of the epidemiologic investigation indicated that the birds suffered from CIAV experienced retardation in growth, depression of immune response and co-infection with other pathogens, and increasing mortality.The fragments consisted of the whole VP3 and parts of VP1 and VP2 of three positive samples were amplified, and sequenced. The results of homologous comparisons of the nucleotide sequence indicated that Guangxi CIAVs were 98.4% identical with those of other domestic and oversea isolates.