A 29-plex MOL-PCR assay for simultaneous detection of selected major, non-typing, and accessory virulence genes in...

Clostridium perfringens is an important pathogen of humans and animals, responsible for a broad spectrum of diseases mediated by diverse toxins and virulence factors. Precise and extended toxin-gene profiling is valuable for strain characterization and molecular epidemiological surveillance. Here, we describe the development of a 29-plex Multiple Oligonucleotide Ligation PCR (MOL-PCR) assay that enables the simultaneous detection of a large and important panel of 27 C. perfringens toxin-related genes - covering major typing toxins as well as an extended panel of non-typing and accessory virulence genes - thus moving beyond the classical toxinotyping framework. The assay was evaluated in comparison with six multiplex qPCR assays. In both systems, the gene encoding the Clostridium perfringens-specific serine O-acetyltransferase (EpsC) was used as a molecular marker for species confirmation, and an internal amplification control was included to detect potentially false-negative results. Analytical specificity testing confirmed exclusive amplification in C. perfringens and sequencing confirmed the toxin-gene profiles of reference strains. Comparative analysis of 72 reference and field isolates (1,944 data points) demonstrated complete concordance for 637 positive detections, yielding 100% positive agreement and 99.7% negative agreement relative to the comparative qPCR method. The limit of detection was 100 fg/µl (approx. 3 × 10¹ genome equivalents; GE) for qPCR and 1  pg/µl (approx. 3 × 10² GE) for MOL-PCR. Despite its high multiplex level, MOL-PCR showed high agreement with qPCR. The developed MOL-PCR method provides a rapid, high-throughput, and cost-effective tool for expanded toxin-gene profiling of C. perfringens isolates targeting major typing toxins and selected non-typing and accessory virulence genes. Therefore, it may support advanced toxin-gene characterization, molecular epidemiology, and One Health-oriented surveillance of evolving virulence landscapes.