How does Bridging PCR (BPCR) work?

The principle for BPCR is described in the steps below.

1. Shared Sequence Region: Two DNA templates have a central region of similar sequence  surrounded by regions of different sequences.
2. Interruption: If one template has an interruption in its sequence, its primer can only extend up to that interruption point.
3. Creation of New 3' End: Synthesis up to the interruption creates a new 3' end at the interruption site. 
4. Annealing and Primer Extension: In the next PCR round, this new 3' end anneals to the second template in the shared sequence region. 
5. Synthesis on Second Template: Primer extension proceeds to the end of the second template, creating a molecule with both primer binding sites from different templates.
6. Exponential Amplification: This new molecule, now containing both primer binding sites, undergoes exponential amplification in subsequent PCR rounds.