Detection of proviral sequences in MPS I tissues. (A) Proviral -ID and genomic control dystrophin (MD) PCR on day 21 transduced adherent layer LTMC cells from dogs M2 through M6. The vectors used for each culture were M-M48ID and L-LCIDSN. Positive controls were 10% M48ID producer cell line DNA mixed with 90% untransduced MPS I canine DNA and 1% M48ID producer cell line DNA mixed with 99% untransduced MPS I canine DNA. All samples and control DNA mixes were positive for dystrophin sequences, and all transduced LTMCs were positive for proviral -ID. Untransduced LTMC DNA from dog M6 (UM6) and reagent controls were negative for proviral sequences. (B) Semiquantitative neo^r and genomic control dystrophin PCR on LTMCs transduced with M48ID (L1) and LCIDSN (L2); postinfusion blood (PB) and marrow (BM) cells from M2 with 0.01%, 0.1%, 1%, and 10% positive control mixed with untransduced canine DNA; and negative untransduced control (0). (C) PCR amplification and Southern blot analysis of 10 CFU from M2 at 1 year postinfusion; dystrophin genomic control (MD), proviral -ID (ID), and neo^r (neo) PCR analysis. This sample demonstrates 10 CFU positive for genomic DNA (MD) and 1 of 10 CFU positive for both -ID and neo^r sequences (CFU 5). Abbreviations: M, marker lane; MC, methylcellulose control; RC, reagent control; +C, positive control DNA.