Studies On Some Epidemiological Characteristics Of Reticuloendotheliosis Virus And Its Recombinant Vaccine

In order to prevent Avian Reticuloendotheliosis Virus (REV), we begin our research of the REV vaccine from two different ways.First, a recombinant baculovirus expressing reticuloendotheliosis virus env gene was constructed with Bac-to-Bac Baculovirus Expression Systems. After transfecting the recombinant virus into Sf9 cells for 3 days, REV env can be detected by indirect immunofluorescence antibody assay (IFA) and Western blot with specific monoclonal antibodies of REV. The oil-water emulsion vaccine was then produced using this infected Sf9 cells lycates and inoculated SPF chickens to validate the immunogenicity for REV. The results show that special anti-REV antibody can maintain more than 45 days and resist the infection of REV viruses. This is the first success to induce anti-REV antibody in chickens by none-live viruses.Second, two kind of vaccines were prepared with CEF infected by REV and specific oil in different concentration. Sanhuang hens were vaccinated in different dose with these two kinds of vaccine. After the experiment,we can find that the dose of vaccine has a sighnificant relationship with immunogenicity of chicken and the optimal dose is 6×105 CEF. The chicken of the vaccinated hens has the maternally derived anti-REV antibody, and can resist the REV infection, hens and its eggs have anti-CEF antibody, it is rarely exist in chickens of the vaccinated hens.In order to investigate cross-antigen of different strains of Avian Reticuloendotheliosis virus(REV) and horizontal transmission of REV in isolated conditions. The 66-day-old chickens inoculated with three strains of REV were separately raised together with control chicken in isolated conditions for 89 days,and then were taken from the isolated condition to the nature condition. On the 169th day after infection, the experiment wasended. Based on the data of ELISA, we found that anti-REV antibody was high in infected chicken ,but no antibody in control chicken in isolated condition. However, in the nature condition the control chicken were infected in the 43days after taken from the isolated condition, and the level of anti-REV antibody in control chicken was closeto the infected chicken. So we can conclude that for the 66-day-old chicken, horizontal transmission of Avian Reticuloendotheliosis is not the main way in isolated conditions.When the titer of the anti-REV antibody in chicken is higher than pre-expected value, we collected enough serum to do the experiments of IFA and viral neutralization assay to study the cross-antigen of the three strains of REV. Based on the serological assay , we can conclude that the antigen of the three REVs is similar to each other.To investigate the epidemiology of REV, virus isolation and serum detection were thoroughly studied.It' s important to choose the proper organs forvirus isolation. In this experiment, 7-day-old chicken were inoculated with the HA REV and SD REV. On 21 days after inoculation, chicken were killed and all kinds of organs were collected. Based on the result of dot blot hybridization assay, busal and lung are the best organs to isolate virus, the infected weather is deserved to be recommended. To our suiprise .there is no virus in liver.In ordor to study the relationship of sensitivity between IFA and ELISA, we have done the following experiment by detecting maternal antibody of REV in chickens. The serums containing maternally derived antibody of Reticuloendotheliosis virus (REV) were collected from Guangdong Sanhuang chicken in different days.Through the experiments of ELISA and IFA to detect the antibody levels ,we can conclude that the sensibility of IFA is greater than ELISA , the S/P values are similar to the IFA values that is the n value of the dilutions(10×2~n). The half life of maternally derived antibody is about 3 days.