FIG. 2.

Southern blot analysis of the phtA gene. Genomic DNA prepared from 23 strains represented in current pneumococcal PS vaccines, as well as strain SJ2, were digested with BamHI and PvuII. Southern blots were probed with a PCR-generated fragment encompassing the phtA gene (A), the 5′ region (B), or the 3′ region (C) of the phtA gene. Serotypes are identified at the top of each lane. HindIII-digested λ DNA (M) was included, and the molecular weights are shown in kilobases. (D) Schematic representation of the proposed recombination between phtA (open box) and phtB (hatched box) genes of certain strains of S. pneumoniae. The thin line denotes flanking genomic DNA. The phtA-phtB hybrid gene shown is based on the sequence information of pneumococcal strain, ATCC 10354 (serotype 15B). Restriction fragments expected after BamHI and PvuII digestion are shown.