Development of conventional and real time PCR assays for rapid species authentication of mammalian cell lines commonly used in veterinary diagnostic laboratories.

Mammalian cell lines are valuable tools in biomedical fields, with applications ranging from disease diagnosis to the production of biological reagents and vaccines. Here we report the development of new conventional (cPCR) and real time PCR (qPCR) assays for species identification of several mammalian kidney cell lines originated from swine, green monkey, hamster and bovine tissues that are extensively used in veterinary diagnostic laboratories. The PCR primers and probes were selected from highly conserved mitochondrial genes and analyzed in silico by nucleotide BLAST in the National Center for Biotechnology Information (NCBI) website to ensure target specificity. The assays were highly species-specific and had no cross-reactivity against other tested cell lines originated from different mammalian species. Assay sensitivity (limit of detection; LOD) was determined using serial dilutions of cell line DNA as template. The estimated LODs were between 2.95 and 48 pg (picogram) DNA/assay for cPCR, and between 1.5 × 10−3 and 4.8 × 10−2 pg DNA/assay for qPCR. Multiplex qPCR assays were developed for simultaneous detection of up to three species in a single assay. The multiplex qPCR assays exhibited the same sensitivity as the corresponding singleplex assays with the exception of the green monkey species that demonstrated a 10–100 fold decline in the sensitivity. Contamination of swine cells was detected in one of the rabbit cell lines. The contamination was further confirmed by Sanger and Next-Generation sequencing.