New Trypanosoma evansi Type B Isolates from Ethiopian Dromedary Camels

Abstract

BackgroundTrypanosoma (T.) evansi is a dyskinetoplastic variant of T. brucei that has gained the ability to be transmitted by all sorts of biting flies. T. evansi can be divided into type A, which is the most abundant and found in Africa, Asia and Latin America and type B, which has so far been isolated only from Kenyan dromedary camels. This study aimed at the isolation and the genetic and phenotypic characterisation of type A and B T. evansi stocks from camels in Northern Ethiopia.Methodology/principal findingsT. evansi was isolated in mice by inoculation with the cryopreserved buffy coat of parasitologically confirmed animals. Fourteen stocks were thus isolated and subject to genotyping with PCRs targeting type-specific variant surface glycoprotein genes, mitochondrial minicircles and maxicircles, minisatellite markers and the F1-ATP synthase γ subunit gene. Nine stocks corresponded to type A, two stocks were type B and three stocks represented mixed infections between A and B, but not hybrids. One T. evansi type A stock was completely akinetoplastic. Five stocks were adapted to in vitro culture and subjected to a drug sensitivity assay with melarsomine dihydrochloride, diminazene diaceturate, isometamidium chloride and suramin. In vitro adaptation induced some loss of kinetoplasts within 60 days. No correlation between drug sensitivity and absence of the kinetoplast was observed. Sequencing the full coding sequence of the F1-ATP synthase γ subunit revealed new type-specific single nucleotide polymorphisms and deletions.Conclusions/significanceThis study addresses some limitations of current molecular markers for T. evansi genotyping. Polymorphism within the F1-ATP synthase γ subunit gene may provide new markers to identify the T. evansi type that do not rely on variant surface glycoprotein genes or kinetoplast DNA.

Prevalensi Penyakit Surra pada Sapi Potong di Kecamatan Cluring Banyuwangi

“…Pemeriksaan yang menunjukkan hasil negatif pada penelitian ini bisa disebabkan oleh kegagalan T. evansi berkembang biak akibat tidak mampu beradaptasi dalam tubuh host (Birhanu et al, 2016).…”

Trypanozoma equiperdum bij het paard – een onbekende bedreiging?

“…T. evansi lack the maxicircle genes, but T. equiperdum does have, although with major deletions of some genes. So far, no akinetoplastic (lacking all kDNA) T. equiperdum have been observed (Birhanu et al, 2016). Two biological features differentiate T. evansi and T. equiperdum from the T. brucei.…”

“…In view of this fact, the actual course of the disease caused by these two trypanosome species was uncertain due to the close similarity in their ultrastructure, genetic makeup and antigenic nature, as has been demonstrated by the fact that the two species have shown similar genetic and antigenic expression (Touatier, 2000;Verloo et al, 2001;Claes et al, 2003a,b). However, recent findings of whole genome analysis of T. evansi and T. equiperdum provided new insights of their distinction and their relation with the different T. brucei subspecies (Birhanu et al, 2016;Cuypers et al, 2017). Both are evolved from T. brucei but with different geographical origins.…”

Development of a recombinase polymerase amplification lateral flow assay for the detection of active Trypanosoma evansi infections

“…T. evansi parasites are classified into two groups based on their kDNA minicircle type [24], which are characterised by the presence (Type A) or absence (Type B) of the gene encoding the RoTat1.2 variant surface glycoprotein (VSG) [25,26]. T. evansi Type B are less commonly found and have only been reported to occur in certain regions in Africa [27][28][29][30][31][32].…”

“…The DNA of killed trypanosomes does not remain in the blood for more than 24 to 48 hours, thus PCR-based assays are highly suitable for the detection of active infections [39]. Several genes have been investigated as targets for the PCR-based diagnosis of T. evansi; these include the RoTat1.2 VSG gene (Type A specific) [40][41][42], ribosomal DNA [43], a region from r-RNA internal transcribed spacer 1 (ITS-1) [44], the gene encoding the invariant surface glycoprotein ISG-75 [45], and the VSG JN 2118Hu gene (Type B specific) [26,28,46,47]. The drawback of PCR-based methods is that they require well-trained and experienced personnel and a laboratory environment suitable for correct protocol execution.…”