Epidemic Investigation of Co-infection of MDV,CAV and REV in Spontaneous Diseased Chicken Flocks in China

The tissues samples of 828 chickens suspected to be infected by immunodepressive viruses from 42 shicken flocks were collected in Shandong, Henan,Hebei,Beijing,Jiangsu,Guangdong,Guangxi,Sichuan,Jilin,Liaoning and Taiwan,and the DNA was extracted for hybridization in Dot-blot with probes for Marek′s disease virus(MDV), Reticuloendotheliosis virus(REV) and Chicken anemia virus(CAV). The results indicated that the checkout ratios of the three viruses are 83.94%(MDV),61.0%(CAV)and 57.25%(REV);the ratios of triple infection,dual infection,single infection and negative are 44.69%,31.16%,15.34% and 8.82%; respectively;29 of 42 chicken flocks occur triple infection(69.05%),5 ones occur dual infection of MDV and CAV(11.90%)3 ones occur dual infection of MDV and REV(7.14%),and two ones not occur MDV、CAV and REV; all the 11 provinces exist MDV,CAV and REV. The results indicated that existing in wide range and co-infection of MDV,CAV and REV in chickens are the important causations for descent of poultry production performance , high incidence opport unistically pat hogenicdiseases and int umescentia provent ricularis in China.