Comparison Of The Pathogenicity Of ALV-J Related Acute Fibrosarcoma Extract Inoculated On Embryos And Chicks

Avian leukosis virus subgroup J was first isolated from Britain chicken in1988, it causedgreat harm to the poultry industry all over the world, especially the broiler breeding in thepast twenty-five years, and the economic losses cannot be estimated. Similar with thetraditional ALV-A and ALV-B, most of the ALV-J can cause chronic tumor with longincubation period and low incidence. In2010, Liu Shaoqiong found a case caused by ALV-Jrelated acute fibrosarcoma from a817miscellaneous broiler. Wang Xin also found a similarcase from a postpartum Hyline Brown laying hens. After the corresponding test verification,Li Chuanlong et al began a systematic study on the virsus seperated frome the817miscellaneous broiler, but our research focused on the ALV-J isolated from the HylineBrown laying hens. We inoculated SPF embryos to simulate the state closer to the verticaltransmission of the ALV-J, and compared the pathogenicities of ALV-J related acutefibrosarcoma extract which inoculated on embryos and chicks.In this study, the new generation of fibrosarcoma was grind into a1:6suspension with PBS,and then centrifugated in4℃and12000r/min for5min. The extract of the tumor was filteredthrough0.22μm filter. The extract was inoculated in CEF cells for9days, and then IFAverified the existence of ALV-J and estimated its TCID50. Later, acute fibrosarcoma extractwas inoculated on yolk sac of5-day-old-embryos, chorioallantoic membrane of11-day-old-embryos and intraperitoneal inoculation of1-day-old SPF chicks, counting the cancerincidence and mortality rates of the embryos. At the age of the first days、1-6weeks, wecollected aseptic anticoagulant, cloacal swabs, weighed, detect each group chicks with drugdetoxification. At the age of one week, we immune Newcastle disease, avian influenza virusH5and H9subtype vaccine to every chick. Three weeks later, we collect serum samples forthree consecutive weeks and determine the antibody titers of each vaccine, ALV-J antibodylevels, as well as the immune organ index of chicks at the age of six weeks. Every dead chickshould be necropsied for the gross lesions and pathological changes within six weeks. The results showed that the mortality of yolk sac inoculation was14/30at the age of18-22days, the incidence of visceral sarcoma was8/14. The mortality of chorioallantoic membraneinoculation was17/30at the age of18-22days, the incidence of visceral sarcoma was6/17.We can observe from dynamic variety of viremia and cloaca p27that the chicks could notonly cause high mortality(100%), but also the viremia and cloacal detoxification(100%) afterchorioallantoic membrane inoculation. As weeks increase, the viremia and cloacaldetoxification of the remaining two toxic groups were also changing, the viremia’s detectionrate of yolk sac inoculation could be100%at the age of three weeks, but for theintraperitoneal inoculation of1-day-old SPF chicks, the viremia’s detection rate will reach75%of the highest at the age of four weeks, the highest detection rate of cloaca p27in thesetwo group were only70%(inoculated on yolk sac, at the age of4-6weeks) and41.2%(intraperitoneal inoculation of1-day-old chick, at the age of1week). As to thepathogenicity of the chicks,13hatched chicks which were the chorioallantoic membraneinoculation all died,11of them had visceral sarcoma.When we collect serum samples for three consecutive weeks and determine the antibodytiters of Newcastle disease, avian influenza virus H5and H9subtype vaccine, we found theALV-J related acute tumor virus had different degrees of immunosuppressive effect to thesethree vaccines, it could reduce the immune effect of the vaccines. Compared with the immuneorgan index of different groups at the age of six weeks, we found the virus can inhibit thedevelopment of the bursal significantly. We also found that the number of white blood cellsreduced significantly when the inoculation chicks in the incidence of near death.The histopathological observation showed that the chicks could cause the light red mucusaccumulation in abdominal which was closely related to the growing of sarcoma;the livertumor characterized by sarcoma and hemangioma, with the prolongation of the infection timewithin a certain time, the tumor became more obvious.These results indicated that the ALV-J related acute fibrosarcoma extract which isolatedfrom Hy-Line Brown laying hens has the effect of tumorigenic to embryos and chicks. Thepathogenic mechanism of different inoculation methods are not exactly same. Thepathogenicity of chorioallantoic membrane inoculation was higher than those inoculated onyolk sac of embryos and those intraperitoneal inoculation of1-day-old SPF chicks. Chorioallantoic membrane inoculation not only caused high incidence of visceral sarcoma,but also the sarcoma occurred earlier and faster, so it can be used as further acutefibrosarcoma model of artificial disease.