Abstract:

【Objective】 To examine the integration of reticuloendotheliosis virus (REV) gene in FPV genome, and to study on the changes of the specific antibody against REV in FP flocks, the cytopathic effect in tissue cells infected by FPV and the histopathological changes in FP chickens. 【Method】 Fowlpox viruses (FPV) were isolated from 9 typical fowlpox (FP) clinical cases identified in Taian and surrounding areas, using PCR to amplify REV-env, LTR sequence, ELISA to test the changes of the specific antibody against REV in FP flocks, electron microscopy to observe the morphous of FPV, and histopathological examination of FP chickens. 【Result】 The results showed that all of the 9 FPV isolates were integrated with REV gene, the tight sphere of the nucleus in infected tissue cells transformed into helix pattern, antibody levels against REV in FP chickens increased significantly. Besides the common pathological changes caused by FP, severe atrophy of spleen, thymus, Bursa, reticuloendothelial cell proliferation, pathologic changes of liver, duodenum and lung were also found. The results of SPF chickens experimental infection by separated and purified FPV showed that the changes of antibody against REV and pathological changes of organs during the healing stage were identified as the changes caused by wild virus. 【Conclusion】 In summary, integration of FPV with REV gene is common in chickens from Taian and surrounding areas, and the pathogenicity of the wild FPV strains integrated with REV gene has changed to some extent.

Key words: fowlpox virus, reticuloendotheliosis virus, gene integration, pathological changes, pathogenicity