Extensive research and clinical trials have been set up to investigate the utility and impact of cell and gene therapies for conditions ranging from cancer, orphan diseases, and common chronic illnesses. Retroviral and Lentiviral gene therapies result in integration, long-term gene expression, and lasting therapeutic effects. Although Replication Competent Retroviruses (RCR) and Replication Competent Lentiviruses (RCL) are designed to be replication defective, potential recombination events leading to replication competent RCR and RCL during cell product manufacturing and infusions is seen as a safety risk. Regulatory agencies recommend testing the presence of competent RCR and RCL during post-infusion monitoring and cell product manufacturing. Viracor has designed, developed, and validated assays to detect RCR and RCL vectors integrated into therapeutic T cells in Peripheral Blood Mononuclear (PBMCs) using Gibbon-ape leukemia (GALV) envelope and Vesicular Stomatitis Virus Glycoprotein (VSV-g) genes as targets, respectively. Both assays demonstrated acceptable Precision, Accuracy, Analytical Specificity, and Linearity and Dynamic Range. These assays are used in safety studies during clinical trials.