Extensive rearing hinders Maedi-Visna Virus (MVV) infection in sheep Iratxe Leginagoikoa, Ramón A. Juste, Jesse Barandika, Beatriz Amorena, Damián De Andrés, Luis Luján, Juan Badiola and Eduardo Berriatua Vet. Res., 37 6 (2006) 767-778 Published online: 15 September 2006 DOI: 10.1051/vetres:2006034