[Development of lymphocyte subsets in milk from ewes excreting Maedi virus]

Milk is the most important route of lentivirus spread in sheep and goat. Blood and milk cell populations were characterised with specific monoclonal antibody at lambing time in 4 primiparous seropositive ewes. Two of the ewes (3/4 half udders) produced milk with infected cells. The cell number/ml was always higher in milk and blood from virus-producing animals. In ewes which spread infected macrophages CD8 lymphocyte number was increased in blood and milk. Serological tests are able to detect infected animals but virus production is reflected immediately by an increase of CD8 lymphocytes in milk.