ORIGINAL RESEARCH article
Front. Vet. Sci.
Sec. Veterinary Infectious Diseases
Rapid serogroup classification of the footrot pathogen Dichelobacter nodosus using multiplex qPCR of lesion samples from sheep in the Netherlands
Provisionally accepted
Birgitta Duim1*
Niels Dekker1
Reinard Everts2,3,4Margit Groenevelt2,4Joost Hoogeveen1Arjen Timmerman1Heleen Zweerus1
Marian Broekhuizen-Stins1Mohammad Mokbel1
Om P Dhungyel5- 1Utrecht University, Faculty of Veterinary Medicine, Department of Biomolecular Health Sciences, Utrecht, Netherlands
- 2Diergeneeskundig Centrum Zuid-Oost Drenthe, Coevorden, Netherlands
- 3Dutch Sheep and Goat Breeders Association (NSFO), Zaltbommel, Netherlands
- 4Utrecht University, Faculty of Veterinary Medicine, Department of Population Health Sciences, Sustainable Ruminant Health, Utrecht, Netherlands
- 5University of Sydney, Sydney School of Veterinary Science, Farm Animal Health, Sydney, Australia
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Dichelobacter nodosus (D. nodosus) is the pathogen responsible for causing footrot in sheep and goats which poses significant challenges to animal health and welfare. D. nodosus are classified into 10 different serogroups (A – I and M) based on the genetic variation of this fimbrial (fimA) gene. These fimbriae are immunogenic and play an important role in the virulence, making serotyping of these fimbriae valuable for identification and vaccine development. In this study three multiplex quantitative PCR (qPCR) assays, targeting the most commonly prevalent 9 serogroups (ABC, DEF, GHI), were studied for detection of serogroups in foot swab samples collected from Dutch sheep farms. Positive for D. nodosus with pnpA qPCR were 147 samples and a serogroup was detected with qPCR in 144 (98%) samples. The multiplex qPCRs detected significantly more serogroups than conventional serogroup PCRs and detected more than one serogroups in a swab. In 46 samples (31%, 46/147) two to five different serogroups were identified from a single swab sample. In three samples no serogroup was identified, likely due to sequence variation in the fimA gene in these samples. These direct multiplex qPCR tests provide faster, more sensitive and accurate testing for direct classification and quantification of D. nodosus serogroups for studying the epidemiology of footrot and formulation of serogroup specific targeted vaccination strategies for prevention, control and treatment of footrot.
Keywords: fimbriae, footrot vaccination, qPCR, Serotyping, Sheep
Received: 11 Aug 2025; Accepted: 16 Dec 2025.
Copyright: © 2025 Duim, Dekker, Everts, Groenevelt, Hoogeveen, Timmerman, Zweerus, Broekhuizen-Stins, Mokbel and Dhungyel. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Birgitta Duim
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