A newly developed droplet digital PCR for Ehrlichia canis detection: comparisons to conventional PCR and blood smear techniques

The Journal of Veterinary Medical Science

article

Sakulchit WICHIANCHOT¹  Nuttanan HONGSRICHAN²  Cherdsak MANEERUTTANARUNGROJ³  Somchai PINLAOR²  Kantapong IAMROD²  Andaman PURISARN¹  Peerawich DONTHAISONG¹  Panagiotis KARANIS⁵  Burin NIMSUPHAN⁷  Rucksak RUCKSAKEN¹ 

[1] Department of Veterinary Technology, Faculty of Veterinary Technology, Kasetsart University;Department of Parasitology, Faculty of Medicine, Khon Kaen University;Department of Biology, School of Science, King Mongkut’s Institute of Technology Ladkrabang;Bioenergy Research Unit, School of Science, King Mongkut’s Institute of Technology Ladkrabang;University of Cologne, Medical Faculty and University Hospital Cologne;University of Nicosia Medical School, Department of Basic and Clinical Sciences;Department of Parasitology, Faculty of Veterinary Medicine, Kasetsart University

关键词: blood smear;    conventional polymerase chain reaction;    detection;    droplet digital polymerase chain reaction;    Ehrlichia canis;   

DOI  :  10.1292/jvms.22-0086

学科分类：兽医学

来源: Japanese Society of Veterinary Science

【 摘 要 】

Canine monocytic ehrlichiosis caused by Ehrlichia canis infection is a life-threatening vector-borne disease in dogs worldwide. Routine blood smear has very low sensitivity and cannot accurately provide a quantitative result. Conventional PCR (cPCR) and real-time PCR (qPCR) are widely used as molecular methods for E. canis detection. qPCR is quantitative but relies on standard curves of known samples. To overcome this difficulty, this study developed a new E. canis quantitative detection method, using droplet digital polymerase chain reaction (ddPCR). ddPCR was evaluated against cPCR and blood smears. PCR amplicons and genomic DNA (gDNA) from 12 microscopic positive samples were used to identify the limits of detection (LODs) in ddPCR and cPCR. Our ddPCR was assessed in 92 field samples, it was compared with cPCR and blood smears. ddPCR showed LOD=1.6 copies/reaction, or 78 times more sensitive than cPCR (LOD=126 copies/reaction), using PCR amplicons as a template, whereas both ddPCR and cPCR had equal LODs at 0.02 ng gDNA/reaction. In addition, ddPCR had 100% sensitivity and 75% specificity for E. canis detection compared to cPCR and no cross-reaction with other blood pathogens was observed. ddPCR identified more positive samples than cPCR and blood smear. ddPCR improved the overall performance of E. canis detection, with a better LOD and comparable sensitivity and specificity to cPCR. The technique might be helpful for diagnosis of E. canis in light infection, evaluating the number of E. canis and follow-up after treatment.

【 授权许可】

Unknown