Detailed physical maps of five atypical cloned DNA fragments from defective interfering particles of herpes simplex virus type 1 (HSV-1) strain Patton were constructed. Unlike typical cloned fragments of defective HSV-1, these fragments have non-contiguous HSV-1 DNA fused to S region terminal repeat sequences (TRs). While four of the five fragments contained only S region sequences (grossly rearranged), one contained distant UL sequences fused to a portion of TRs.