Development and Evaluation of a TaqMan Real-Time PCR Assay for the Rapid Detection of Cross-Contamination of RD (Human) and L20B (Mouse) Cell Lines Used in Poliovirus Surveillance.

Background: The cross-contamination of cell lines in culture is a persistent problem. Genetically modified L20B (Mouse) and RD (Human Rhabdomyosarcoma) cell lines are commonly used in poliovirus research, surveillance, and diagnostics. Cross-contamination between these cell lines leads to unreproducible results and unreliable surveillance data, negatively affecting public health. The gold standard method for cell authentication is Short Tandem Repeats analysis, which is time-consuming and expensive. The disadvantage of STR is limited detection of interspecies contamination.

Methods: This assay targets the mitochondrial cytochrome c oxidase subunit I (MTCO1) gene, a highly conserved and emergent DNA barcode region for detection of cross-contamination in RD and L20B cell lines. The MagNA Pure Compact instrument and ABI 7500 Fast Dx Real-time PCR systems were used for DNA extraction and to perform real-time PCR respectively.

Results: The newly developed assay is very sensitive with a limit of detection of 100 RD cells/1 million L20B/mL. The amplification efficiency and R-value were 102.26% and 0.9969 respectively. We evaluated specificity of the assay with five human and four mouse cell lines, as well as monkey and rat cell lines. The assay showed no cross-reactivity with genomic DNA from human, mouse, rat, or monkey cell lines. The analytical sensitivity was also evaluated by spiking varying amounts of RD cells (0.001% - 10%) into L20B cells. There was no difference in C values when running single-plex or duplex PCR reactions with similar experimental conditions.

Conclusions: We have developed and validated a TaqMan real-time PCR assay, a sensitive method for the detection of cross-contamination of RD and L20B cell lines.