(A) PCR of the 132-bp region from BAC-derived and wild-type CVI988 viruses. (B) TspRI restriction digestion profile of pp38 PCR product. Lane M, HindIII-EcoRI-digested lambda DNA molecular weight markers; lane F, field MDV isolate; lane R, RB1B virus; lane 1, BAC6; lane 2, BAC19; lane 3, BAC10; lane 4, BAC10, fifth passage; lane 5, BAC10, 10th passage; lanes 6 to 9, viruses isolated from birds 241 (BAC virus-infected), 932, 933, and 941 (BAC DNA-infected), respectively; lane 10, wild-type CVI988 virus.