Submitted to: Poultry Science
Publication Type: Review Article
Publication Acceptance Date: January 31, 2005
Publication Date: January 31, 2005
Citation: Cheng, H.H. 2005. Marek's disease: an evolving problem. Poultry Science. p. 173. Technical Abstract: Marek's disease (MD) is a lymphoproliferative disorder of chickens caused by an infectious pathogen, the Marek's disease virus (MDV). The fact that this book was published only 3 years after a very similar book entitled 'Marek's disease' (Springer) indicates the continued importance of this disease to the poultry industry and scientific community, and the rapid pace of the field. This book also provided the opportunity for the Institute of Animal Health, United Kingdom, to initiate its 'Biology of Animal Infections' series. Chapters 1 and 2 by Pastoret and Biggs, respectively, review the history of this disease and its larger relevance. Many readers, especially those not familiar with the subject, will find these parts entertaining and interesting. For example, it may surprise some that MD provided many key first examples such as the association of the MHC with genetic resistance, the ability to vaccinate and protect against a naturally occurring cancer, and the vaccination of chicks while still embryos. For those aficionados, a more comprehensive review on the early work to tease out MDV as the causative agent for 'fowl paralysis' and the separation from lymphoid leucosis (LL) can be found by the same author in the 2001 book. Chapters 3 and 4 focus on MDV content and viral pathogenesis genes. In chapter 3, besides reviewing the coding content of MDV and related viruses, Osterrieder and Vautherot describe the recent ability to clone the entire MDV genome into a bacterial artificial chromosome (BAC) vector. The technology allows for the generation of infectious clones and, more importantly, the application of well-known E. coli methods for making defined recombinants, which nicely complements the overlapping cosmid clone technology published in 2002 by Reddy et al. (PNAS 99:7054-9). One surprising outcome is the preliminary result indicating many MDV genes are essential for MDV replication even though the herpes simplex virus type 1 (HSV-1) homologs are not required. Chapter 4 by Nair and Kung summarizes and extends the previous 2001 book chapter by Kung on the role of Meq and other viral proteins in transformation and pathogenicity. As stated, 'the quest to unravel the molecular mechanisms of MDV oncogenicity is at an important stage' with the advancements and excitement of the community nicely presented. Chapters 6 to 9 focus on the host response and pathology. In chapter 6, Baigent and Davison review the viral life cycle within the host. The information presents the substantial progress being made on defining where the virus replicates and spreads, what types of cells are infected or transformed, etc. However, it also demonstrates the difficulties in working with MDV, and the need for additional tools and reagents. Chapters 7 and 8 by Payne and Burgess, respectively, summarize information on the various pathological responses in MD and efforts to further refine MD lymphomas. Discussions on atherosclerosis and other avian species remind us that MD is not limited to lymphomas and nerve enlargements of chickens. Material present by Burgess also tells us that our understanding of MD tumor regression is limited though critical for genetic resistance and future vaccine development. Chapter 9 by Bumstead and Kaufman review what is known about MHC and non-MHC genetic resistance to MD, and demonstrates the rapid impact of structural and functional genomic approaches. Chapters 10 and 11 focus on the immune response and the ability of MDV to immunosuppress the immune system. The identification of cytokines and the ability to monitor them are having a major impact on avian immunology, and Davison and Kaiser clearly capture our increased understanding of the immune response with respect to MD and vaccination. Schat reminds us that MDV-induced immunosuppression is a significant problem, especially when reduced immune function can increase susceptibility to other pathogens. Disease outbreaks of MD continue to occur in the field and diagnosis is the subject of chapter 11 by Zelnik. The rapid and accurate diagnosis of MD remains an important issue for the industry in order to properly manage their flocks. The impact of modern molecule tools on pathology is clearly observed. The current problem, vaccinal control, and future control strategies are reviewed in chapters 5 (Marrow and Fehler), 13 ((Bublot and Sharma), and 14 (Gimeno). Not stating the obvious, it is clear that unless a sterilizing vaccine is produced, MD control will require multiple prong approach of biosecurity, vaccination, and genetic resistance. These chapters also highlight the interesting fact that MDV strains of higher virulence continue to emerge. In summary, both the novice and expert will find this book to be highly informative on its own as well as a valuable edition to the field. The book has wide breadth, and the chapters are detailed yet concise enough. A rich collection of figures and table greatly aid the written material. Compared to the 2001 book, this collection of material provides more of a practical focus to the problem. Finally, this is a fitting tribute to Nat Bumstead, a pioneer in the field, who sadly passed away this year.