The Diagnosis Of Atypical ND After Onset Of Illness, Egg Quality At Different Stages After Being Cured Detection And Analysis Of Carriers Of The Virus

As a highly acute, contagious, septic infectious disease, Newcastle disease (ND) which is caused by Newcastle disease virus (NDV) has brought severe injury to Poultry breeding at home and even worldwide. Once the breeding birds infected by Newcastle disease virus, the most perform atypical disease. Although the sick are cured easily, it also cause significantly decreased laying rate, fertilization rate, eggshell quality, and a weak increase in chickling. Even the chickling occur Newcastle disease in the early periods. In order to verify whether the egg produced carrying virus and the proportion of the eggs carried virus, the experiment was specially devised with a view of the prevalence of atypical Newcastle disease in chickens at different times after onset of egg in the analysis of whether the virus detected.In this study, pathology, serology and comprehensive etiology diagnosis were used to test two AA meat breeder flocks suffering from atypical Newcastle disease. Diagnostic results show that: two sick folks had manifestations of the clinical respiratory symptoms, gastrointestinal symptoms and decline in egg production performance of the basic symptoms of atypical Newcastle disease; severe diseased chickens'gastrointestinal tract and respiratory tract showed hemorrhag catarrhal inflammation, follicle hyperemia, hemorrhage, oviduct atrophy; and all the above necropsy lesions were consistent with the characteristic of Newcastle disease. Viral encephalitis, lymphatic tissue necrosis is significance of histological necrosis for Newcastle disease. HI test results before and after the sick, and the Newcastle Disease Virus Isolation and Identification of histological and immunohistochemical detection of positive results are a certificate of Newcastle disease. All are integrated to determine two AA meat breeders'illness were atypical Newcastle.In this experiment, 50 eggs equally were randomly selected from each of two AA breeders flocks which had been infected with atypical Newcastle disease virus and cured (appetite have returned to normal) within 14d and 28d.4 of each 50 eggs were randomly selected to test its Newcastle disease antibodies in yolk by HI. The 92 left were put into a couveuse to incubate after sterilizing, and from the third day the eggs were candled during the remainder of the incubation, the unfertilized eggs and the dead embryos were marked, the dead embryos or embryo allantoic fluid were collected, and then put in -20℃refrigerator to preserve. On the 20th day, the 44 living embryos were put to the -20℃refrigerator to freeze to death. All the materials and embryo allantoic fluid were collected in super clean bench. Embryo bodies or embryo organs were shredded by sterilization of small scissors (internal organs, thymus and brain of the embryos after 12d can be only collected ) , and then grinded in a sterilized grinder, diluted by 5 to 10 times sterile PBS of the expected volume of the materials, put in -20℃refrigerator frozen and thawed 3 times continuously; the dilution was filtered through the 0.22μm membrane, added two kinds of antibiotics, marked, and put in -20℃refrigerator to preserve.Materials were expected to carry out a serological test, RT-PCR experiments, cell isolation and identification. the Results showed that: the eggs without fertilization selected by candling are neither normal in egg shell quality nor in egg shape, with a relatively high yolk antibody titer; no hemagglutinating activity was detected in allantoic fluid samples. 64 disease samples were tested by the method of real-time fluorescent quantitative RT-PCR, and results showed no ct value or amplification curve, indicating that samples were negative and contained no Newcastle disease virus. However, when the disease samples were inoculated into Madin-Darby Canine Kidney (MDCK) Epithelial cells and baby hamster kidney cell (BHK) cells, 23/64 could induce cytopathic effects and plaque formations, which showed that a part of the eggs produced by the cured breeders carried virus. The results showed that after the chicken atypical Newcastle disease for a long period of time, egg quality and decreased fertilization rate and hatching rate decreased and the weak child rate increased significantly. In the premise of High levels of egg yolk antibodies, the probability of infected chicken embryo is not high, a limited number of eggs is difficult to find samples of Newcastle disease virus. Chicken flocks hatching incidence of early onset may be mainly related to the incubation and hatching process of virus contamination. After the disease samples from embryos were inoculated into hamster kidney cells and canine kidney epithelial cells, high rates of cell lesions were observed, but no Newcastle disease virus was detected. Further study and research is needed to explore the reason. Our results provide certain reference value for the correct evaluation of the effects of atypical Newcastle disease on breeder chickens and its pathogenesis.