Analysis of Dipylidium caninum tapeworms from dogs and cats, or their respective fleas - Part 1. Molecular characterization of Dipylidium caninum: genetic analysis supporting two distinct species adapted to dogs and cats.

Michel Labuschagne,Jacques Guillot,Steffen Rehbein,Josephus Fourie,Dionne Crafford,Frédéric Beugnet

doi:10.1051/parasite/2018028

Abstract

A 28S rDNA PCR detection assay was previously developed to identify Dipylidium caninum DNA inside single fleas collected from both cats and dogs. Sequence analysis of the 28S rDNA fragment indicated two genetically distinct variations of the target region. The two genotypes, so-called “D. caninum canine genotype” and “D. caninum feline genotype”, based on host origin, are further investigated and described in this paper. Restriction fragment length polymorphism (RFLP) analysis and hydrolysis probe-based genotyping assays were developed and validated for genotyping D. caninum DNA. The complete mitochondrial (mt) genome of the “feline genotype” was sequenced and compared to the D. caninum mt genome available in GenBank. The molecular characterization of D. caninum isolates collected from infected fleas, and also proglottids collected from dogs and cats, confirmed the existence of two distinct genotypes. These genotypes are related to host origin (dogs or cats), irrespective of their geographical origin, and they present a biological adaptation to their respective host, as confirmed by the comparison of biological development and host preference in another study. The genetic differences (Part 1, present paper) and biological observations (Part 2, in this journal) enabled us to suggest the existence of two distinct species within D. caninum, which will have to be clarified.

Highlights

Dipylidium caninum (Linnaeus, 1758), a globally distributed cestode, infects domestic cats and dogs [8], wild canids and felids [7,10], and occasionally humans [15]
The molecular characterization of D. caninum isolates collected from infected fleas, and proglottids collected from dogs and cats, confirmed the existence of two distinct genotypes
DNA sequence analysis of a 655 bp region of the 28S ribosomal DNA region used in the D. caninum detection PCR resulted in the identification of two unique groups when these DNA sequences were compared to the GenBank reference sequence (Table 5)

Summary

Introduction

Dipylidium caninum (Linnaeus, 1758), a globally distributed cestode, infects domestic cats and dogs [8], wild canids and felids [7,10], and occasionally humans [15]. The cat flea, Ctenocephalides felis, is considered the main intermediate host of D. caninum [5]. C. felis has the ability to infest both dogs and cats. The dog flea (Ctenocephalides canis) acts as an intermediate host, but exceptionally infests cats. The life cycle of D. caninum can be summarized as follows: flea larvae ingest eggs of D. caninum, followed by development of the egg to the metacestode stage inside the flea. When a canine or feline host ingests adult fleas infected with suitably developed metacestodes, the parasite establishes in the small intestine of its definitive host

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