Direct cytolytic activity of pbmc from pigs infected with porcine reproductive and respiratory syndrome J.N. Samsom, J.J.M. Voermans, M.G.M. de Bruin, E.M.A. van Rooij, J.M.A. Pol and A.T.J. Bianchi Vet. Res., 31 1 (2000) 44 DOI: 10.1051/vetres:2000046