Molecular Characteristics of gp90 Gene of 14 Reticuloendotheliosis Viruses Isolated in China

[Objective] The paper was to study molecular characteristics of gp90 gene of 14 Reticuloendotheliosis viruses isolated in China.[Method] The surface envelop gene gp90 of 14 REV strains isolated from different commercial layer farms in China were amplified,and their nucleotide sequences were determined.[Result] Sequence analysis showes that 14 REV strains are more identical to the subtype 3 isolates than to the early Chinese REV isolates.In addition,14 REV strains have a high identity with some REV strains in US and Taiwan.[Conclusion] The study provided necessary information for further understanding the evolution of REV.

Maternal Antibody Protected Chicks from Growth Retardation and Immunosuppression Induced by Early Reticuloendotheliosis Virus Infection

To determine if the maternal antibody from breeders vaccinated with cell culture-adapted reticuloendotheliosis virus （REV） could protect chicks from early REV infection, one-day-old chicks with or without anti-REV maternal antibodies were inoculated with REV, and then their growth rates and antibody titers to Newcastle disease virus （NDV） and avian influenza virus （AIV）, after vaccination with inactivated vaccines, were compared. This study indicated that REV infection could cause growth retardation and severely inhibit immune reactions to inactivated vaccines against NDV and Avian influenza virus （AIV, H9 and H5） in one-day-old broilers without maternal antibodies specific to REV. Maternal antibody from breeders vaccinated with an attenuated REV vaccine effectively protected REV-challenged birds from growth retardation and immunosuppression on antibody reactions to NDV and AIV vaccines. Four weeks after vaccination, the HI titers to NDV, AIV-H9, and AIV-H5 in maternal antibody positive and negative groups were 3.36 ＋- 2.04 versus 1.58± 1.69 （P〈0.01）, 6.27±3.87 versus 0.71 ± 1.60 （P〈0.01）, and 6.72±3.92 versus 0.54± 1.44 （P〈0.01）. Maternal antibodies from breeders vaccinated with REV vaccine could successfully protect chicks from REV infection and effectively prevent REV-induced growth retardation and immunosuppression in antibody responses to NDV and AIV.

Dynamic Pathology and Antigen Location Study on Broiler Breeders with Coinfection of Marek's Disease Virus and Reticuloendotheliosis Virus

To further understand the generation and development of coinfection of Marek＇s disease virus （MDV） and reticuloendotheliosis virus （REV） in broiler breeders, and then find the method and optimal time of differential diagnosis for complex clinic multiple infection, the authors studied the pathohistological changes, apoptosis, immunohistochemistry （immunofluorescence）, and ultrastructure of tumor tissues of broiler breeders inoculated with MDV and REV. The study showed that proliferation of small lymphocytes was seen in the main organs at the age of 1 week, then immature lymphocytes, all kinds of lymphocytes, primitive reticulum cells, and Marek＇s disease cells （MDCs） were observed at 2-9 weeks. Apoptosis of lymphocytes could not be seen until the age of 10 weeks in the immune system. Immunohistochemistry detection showed that the positive signs of MDV and REV antigen were observed in the main organs at 2 weeks of age. Multi-morphology lymphocytes, MDV, and REV, mitotic figures and apoptosis of lymphocytes were observed with the help of transmission electron microscopy. MDV cooperating with REV promotes the course of disease of coinfection. Differential diagnosis can be done by immunohistochemistry in the early stage （before 2 weeks）, and histopathology in the late stage （post 4 weeks）. MDCs, primitive reticulum cells, immature lymphocytes, and two kinds of virions can serve as a basis for bistopathology differential diagnosis.

Influence of REV and ALV-J Co-Infection on Immunologic Function of T Lymphocytes and Histopathology in Broiler Chickens

The aim of present investigation is to study the effect of single- and co-infection with REV and ALV-J on T lymphocytes bioactivities and histopathology in broiler chickens. The bioactivities of blood and spleen T lymphocytes including lymphoproliferation responses, cytotoxicitic responses, and histopathology of spleen were detected in broiler chickens singly- or co-infected with REV and ALV-J at different days post inoculation and the virus expressions in spleen of infected broiler chickens were detected with immunofluorescence assay （IFA）. The results indicated that blood and spleen T lymphocytes proliferation responses and cytotoxicity in broilers infected with REV or/and ALV-J were inhibited in the whole observed period compared with controls. In the co-infected chickens they were highly inhibited than in the single-infected. The histopathology of spleen in infected chickens at 17 and 37 d post inoculation （dpi） indicated that cell interium increased, the numbers of lymphocytes decreased, and the regrowth were destroyed or decreased, especially more significantly at 17 than at 37 dpi. The different numbers of virus were detected in spleen lymphocytes in REV- infected and/or ALV-J-infected chickens. In the spleen of co-infected chicken, both REV and ALV-J were detected and the total numbers of viruses were more than in chickens singly-infected with REV or ALV-J. Thus, the co-effect of REV and ALV-J caused more immunosuppression on T lymphocytes bioactivities in broiler chickens than single-effect of ALV-J or REV, which contributed to the sever histopathology and the product of tumor cells. This study will be helpful for understanding the effect of co-infection with many viruses and control them in poultry.