1. From the Institute of Cardiology (L.P., F.G., G.M., L.T., F.C., C.M, A.B.) and the Institute of Experimental Medicine, Section of Microbiology (G.F., T.L., L.G., M.P.L.), University of Bologna, Bologna, Italy; and the Department of Virology, Institute of Microbiology, Albert Einstein University, Ulm, Germany (G.F.).