Results of ethidium bromide staining (panel A) and corresponding Southern hybridization (panels B and C) of RT-PCR products of eight calf herd (CH) samples (A) M= molecular mass marker, lane 1: CH124; lane 2: CH125; lane 3: water; lane 4: CH126; lane 5: CH138; lane 6: water; lane 7: CH139; lane 8: CH145; lane 9: water; lane 10: CH156; lane 11: CH176; lane 12: water; lane 13: human NLV positive control (5); lane 14: water. For Southern blot hybridizations, a set of probes used to detect NLVs in h