FIG. 2.

Subclones of pNAD1 constructed in the E. coli–A. pleuropneumoniae shuttle vector pGZRS18 (25). The location of the nadV gene is indicated with an arrow. Plasmids pGZNAD1, pGZNAD7, and pGZNAD8 were constructed using the restriction sites shown. Plasmid pGZNAD9 was constructed using synthetic primers to PCR amplify the nadV gene. The ability of these clones to confer NAD independence on A. pleuropneumoniae is indicated in the right-hand column. Restriction sites: A, AvaI; B, BamHI; E, EcoRI; and P, PstI.