Herpesvirus connection in the expression of autoimmune vitiligo in Smyth line chickens

The Smyth line (SL) chicken is an animal model for human vitiligo, a common acquired depigmentary disorder affecting about 1-2% of people worldwide, T he vitiligo-like depigmentation in SL chickens typically develops when the birds are between 6 and 14 weeks of age and mag affect 70-95% of hatch mate s. The development of SL vitiligo is considered to depend on two interactin g components, namely an inherent melanocyte defect and an autoimmune reacti on to melanocytes, Recently, a role for an environmental factor in the expr ession of vitiligo was suggested by the observation that only 10% of SL chi cks imported from the University of Massachusetts (UM) and reared in isolat ion at biosecurity level 2 (BSL 2) at the University of Arkansas (UA) exhib ited vitiligo, Following further assessment of environmental differences be tween UA and UM SL chickens, three environmental factors that may have infl uenced the expression of SL vitiligo were identified. Included were housing condition, status of Mycoplasma synoviae infection, and turkey herpesvirus (HVT) vaccination status. Studies mere subsequently conducted at UA and UM to assess the role of these environmental factors in the expression of SL vitiligo, M, synoviae infection was not found necessary for vitiligo expres sion in SL chickens. However, HVT emerged as a strong candidate for an impo rtant environmental factor in SL vitiligo, The connection between HVT and S L vitiligo,was confirmed for both BSL 2 and conventional housing. Therefore , the observations reported here suggest a strong causative link between HV T infection and SL vitiligo.