Development of PCR/dot blot assay for specific detection and differentiation of taeniid cestode eggs in canids

Abstract

We report the development of a colourimetric PCR/dot blot assay targeting the mitochondrial gene NADH
dehydrogenase subunit 1 (nad1) for differential diagnosis of taeniid eggs. Partial sequences of the cestode
nad1 gene were aligned and new primers were designed based on conserved regions. Species-specific
oligonucleotide probes (S-SONP) for canine taeniid cestodes were then designed manually based on the
variable region between the conserved primers. Specifically, S-SONP were designed for the Taenia crassiceps,
T. hydatigena, T. multiceps, T. ovis, T. taeniaeformis, Echinococcus granulosus (genotype 1), E. multilocularis and E.
vogeli. Each probe showed high specificity as no cross-hybridisation with any amplified nad1 fragment was
observed. We evaluated the assay using 49 taeniid egg-positive samples collected from dogs in Zambia. DNA
from 5 to 10 eggs was extracted in each sample. Using the PCR/dot blot assay, the probes successfully detected
PCR products from T. hydatigena in 42 samples, T. multiceps in 3 samples, and both species (mixed infection) in
the remaining 4 samples. The results indicate that the PCR/dot blot assay is a reliable alternative for
differential diagnosis of taeniid eggs in faecal samples.