Marek's disease virus and skin interactions.

Marek's disease virus (MDV) is a highly contagious herpesvirus which induces immunosuppression and T-cell lymphoma in chicken. This virus still circulates in flocks despite forty years of vaccination, with important economical losses at the world level. The feather follicles, which allow feathers morphogenesis and their anchor into the skin, are the unique known source of MDV excretion. This tissue causes environment contamination and MDV bird-to-bird transmission. Epithelial cells from the feather follicles are the only identified cells, in which high levels of infectious mature virions are visible by transmission electron microscopy and from which cell-free infectious virions have been purified. Finally, feathers harvested on animals and poultry dust are today considered as excellent materials in order to follow vaccination, circulation of pathogenic viruses and environment contamination. This article aims at summarizing the current knowledge on MDV-skin interactions and at suggesting new approaches which could solve important questions on MDV biology.