Molecular characterization of Trypanosoma evansi, T. vivax and T. congolense in camels (Camelus dromedarius) of KSA

Abstract

Background: Trypanosoma evansi is the leading infectious Trypanosoma spp. in camels (Camelus dromedarius) present in the Kingdom of Saudi Arabia (KSA) that could lead to extensive economic losses. The present study was aimed to assess the prevalence rate of T. evansi in Taif governorate, Makkah province, KSA using parasitological and molecular evaluations, and analyze their genetic relationship targeting internal transcribed spacer 1 (ITS1) and variable surface glycoprotein (VSG) genes. For evaluation, we have used 102 blood samples of camels obtained from three different regions in Taif.

Results: Results show a considerable prevalence rate of trypanosomosis 2/102 (2.0%) according to Giemsa-stained buffy coat smear, and 16/102 (15.7%) according to touchdown PCR. T. evansi (n = 10/102, 9.8%) was the main infectious species found in camels then T. vivax (n = 3/102, 2.9%). Mixed infections were detected in three camels with T. evansi, T. vivax, and T. congolense (n = 3/102, 2.9%). Regarding gender, the results indicate that female camels (11/66, 16.7%) show higher prevalence of Trypanosoma than males (5/36, 13.9%). Sequencing and phylogenetic analyses of ITS1 and VSG showed their relationships with T. evansi in other hosts from different countries.

Conclusions: In our peer knowledge, it is the first time to report a research-based prevalence of trypanosomosis in the camels of Taif governorate, Makkah province, KSA.

Keywords: ITS1; KSA; Phylogeny; Rotat 1.2 VSG; Taif governorate; Trypanosomosis.

Fig. 1

Light micrographs of camels’ blood buffy coat smear showing Giemsa-stained Trypanosoma evansi with long terminal free flagella (white (A) and black arrows (B)) and apoptotic lymphocyte (black arrowhead, (A)). Scale-bars: 10 μm

Fig. 2

Agarose gel stained with ethidium bromide (1.5%) showing PCR product of ITS1 using Kin primers (A and B). Gel (A) Lanes 1,2: Trypanosoma evansi (540 bp), Gel (B) Lane 1: T. vivax (300 bp), and Lane 2: Mixed infection of T. evansi and T. vivax. Gel (C) showing PCR product of ITS1 using ITS1 primers; Lanes 1, 2, 3: Mixed infection of Trypanosoma evansi (480 bp), T. vivax (250 bp), and T. congolense (620 bp). Gel (D) showing PCR product of ITS using IR primers; Lanes 1–7: Trypanosoma evansi (1.1 kbp). Gel (E) showing PCR product of Rotat 1.2 VSG region using ILO primers; Lanes 1–6: Trypanosoma evansi (488 bp). Any other lower and higher bands are non-specific. Lane M: Low molecular weight marker (50–1500 bp)

Fig. 3

Phylogenetic relationships between Taif_camel T. evansi (ITS1) MW960042, and MW960039 (using Kin primers), and MW940705 (using ITS primers) with other reference sequences of T. evansi from NCBI GenBank. Trypanosoma GenBank sequences were shown by their accession numbers, country, and host

Fig. 4

FASTA sequence of Rotat 1.2 VSG region using ILO primers (A). Its relationship with other reference sequences of T. evansi from NCBI GenBank using phylogenetic tree (B). Trypanosoma GenBank sequences were shown by their names, host names (if present in Genbank), and accession numbers. Bar scale represents 0.005 nucleotide substitution per site

Fig. 5

Map of Saudi Arabia showing Taif governorate (A, red arrow), (B) referring to the latitude and longitude coordinates of the present study area of collecting samples according to Google map 2021 (Map source: adapted from Google Maps® 2021)