Epidemiology Investigation And Diagnosis Of Reticuloendotheliosis To Large Scale Farms In Ningxia

Reticuloendotheliosis virus(REV)are a group of avian retroviruses that infect fowl and cause reticuloendotheliosis(RE)including immunosuppression,acute lethality reticuloma,short stature syndrome and chronic neoplastic characterized as lymphopoiesis and other tissue.RE is the third species viral tumor that have been discovered after chicken Marek's disease(MD)and chicken lymphocytic leukemia(AL).Currently,the positive rate of RVE detection reached 20% ~ 30% in China.REV has extensive host,meanwhile,REV causes not only neoplastic disease but also immunosuppression that decreases immune responses and increases the infection of other diseases.REV can spread widely by contaminating biological products and cause huge economic losses.In this study,to investigate the epidemic situation of RE in Ningxia Autonomous Region,1116 serum samples(546 samples from breeding poultry farms,570 samples from commercial chicken farms)were collected from 3 breeding poultry farms and 19 commercial chicken farms totally in 5 cities.REV antibody of the serum samples was detected by ELISA kit and antibody level of AIV H9 and Newcastle disease virus(NDV)was detected using HI assay.The results showed that the value of REV antibody was negative in three breeding poultry farms.However,the positive rate of REV antibody from the commercial chicken farms was 78.9%(15/19).The positive rate of individuals was 3.3%~96.7%,their average value was 28.6%.The antibody titer of AI-H9 and ND from the commercial chicken farms were both higher than 25 in population antibody level and individual antibody level.These results indicated that the immune suppression of ND and AI in REV infection poultry were not obvious.To investigate the co-infection status among ALV,REV and MDV in layer flocks in China,the samples such as serum,feather pulp,anal swab,and diseased organs were collected from suspected ALV infection cases from 16 commercial farms inNingxia province over the past three years.These samples were subjected to molecular biology detection and analysis,histopathological detection,serological assay.The group specific antigen P27 of ALV by ELISA,MDV detection by agar gel immunodiffusion test and histopathological examinations were also taken to differentiate three tumor diseases.The results showed that infection of REV were positive detected by molecular biology detection and analysis,serological assay and histopathological detection.No REV single infection cases existed in all 16 farms.The co-infections among REV,MDV and ALV often happen together.The co-infection cases caused by RE and MD,three diseases(RE,MD and AL),MD and AL were 12,2and 2 in 16 samples,respectively.The results also showed that infection of REV were common phenomena in tumor diseases(14/16).The numbers of co-infection occurrence with RE and MD were higher than those with three diseases(RE?MD and AL)and two diseases(MD and AL).Besides no tumor cases caused by single infection in these 16 samples,the infection rate of MD was 100%(16/16).