Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/8/2010
Publication Date: 3/8/2010
Citation: Fadly, A.M. 2010. Evolution of Avian Tumor Viruses. In: Proceedings 9th Scientific Conference of the Egyptian Veterinary Poultry Association, March 8-10, 2010, Giza, Egypt. p. 41-51. Interpretive Summary:
Technical Abstract: Virus-induced neoplastic diseases of poultry, namely Marek’s disease (MD), induced by a herpesvirus, and the avian leukosis and reticuloendotheliosis induced by retroviruses, can cause significant economic losses from tumor mortality as well as poor performance. Successful control of MD is and has been achieved through use of effective conventional vaccines. For now and the foreseeable future, use of vaccines represents the principal strategy for the prevention and control of MD. However, effective biosecurity measures and genetic resistance are critical adjuncts to vaccination in any successful strategy to control MD. On the other hand, there is no doubt that extensive use of vaccines over the last few decades has contributed to the increase in the tendency of MD virus (MDV) to evolve to greater virulence. This increase in MDV virulence is a critical factor that is considered in developing various strategies for control of the disease, as it tends to make earlier vaccines obsolete. Recent advances in MD research, namely revealing sequence of MDV genome and the development of new molecular approaches to manipulate MDV genome are currently being used to identify and characterize function of important viral genes and to develop more effective recombinant vaccines. In contrast to MD, there is no commercial vaccine available for control of retrovirus virus infection in poultry, namely avian leukosis virus (ALV) and reticuloendotheliosis virus (REV). Eradication programs adopted by primary chicken breeders are the most effective means for controlling ALV infection in chickens. Eradication programs similar to those used to control ALV have not yet been adopted by commercial chicken and turkey breeders for control REV infection. This review is primarily aimed at 1) immunopathogenesis and control of MD, avian leukosis and reticuloendotheliosis, and 2) influence of evolving to more virulent forms or creation of new recombinant strains on diagnosis and control of these diseases.