Dynamics and within-host interaction of Theileria lestoquardi and T. ovis among naive sheep in Oman

Awad, Hoyam; Gadalla, Amal; Postigo, Milagros; Al-Hamidhi, Salama; Tageldin, Mohammed H.; Skariah, Sini; Sultan, Ali A.; Johnson, Eugene H.; Shiels, Brian; Pain, Arnab; Thompson, Joanne; Babiker, Hamza A.

doi:10.1038/s41598-020-76844-2

Cited by 11 publications

(15 citation statements)

References 26 publications

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“…The lower T. lestoquardi parasitemia in mixed infection is indicative of immune pressure (potentially innate in nature), which is expected to impact both parasites (T. lestoquardi and T. ovis). The above ndings are in line with our most recent data, in a cohort study of indigenous sheep in Oman, which revealed a signi cantly higher T. lestoquardi density in single infection vs mixed infection [7].…”

Section: Discussionsupporting

confidence: 92%

“…(T. mutans and T. velifera) has been demonstrated in indigenous African Bos indicus calves [11]. This is consistent with our most recent work in Oman that linked mixed infection (T. lestoquradi plus T. ovis) to signi cant reduction of mortality among local breeds of sheep [7]. The present study extended these earlier ndings and examined clinical and hematological indices in sheep carrying mixed (T. lestoquradi plus T. ovis) compared to single species of T. lestoquardi.…”

Section: Discussionsupporting

confidence: 91%

“…The present study provides additional evidence for within-host interaction of T. ovis and T. lestoquardi in small ruminants in Oman [7]. The density of both parasites was higher when present as a single species infection (presence of one species alone), compared to mixed species infections (presence of the two species), which we believe provides support for the concept of heterologous protection the ability to limit parasite load, conferred by mixed infection with both parasites [11].…”

Section: Discussionsupporting

confidence: 76%

“…Interestingly, some of the sheep had mixed infections with Theileria lestoquardi (pathogenic) and T. ovis (non-pathogenic) [2,6], which are both transmitted by Hyalomma anatolicum, the main tick species, identi ed on animals examined in Oman [2]. Our most recent data illustrated a potential competitive interaction between these two Theileria spp; a substantial reduction in the risk of mortality was observed in mixed parasite infections, suggesting that T. ovis confers protection against lethal T. lestoquardi infection [7]. A protective effect of mixed species infection (T. lestoquardi + T.ovis) against severe Malignant Ovine Theileriosis [MOT], is in line with a large body of data on apicomplexan parasites indicating that mixed infections with different species or genotypes of the same species, may modulate the virulence and pathogenicity of each other [8].…”

Section: Introductionmentioning

confidence: 74%

“…The density of T. lestoquardi and T. ovis parasites was quanti ed using real-time polymerase chain reactions (qPCR). Primers and probes targeting the 18S rRNA gene of T. lestoquardi and T. ovis and details of assay optimization are described elsewhere [7]. Standard curves were generated using quanti ed DNA of T. lestoquardi (9.26 x 10 10 18S rRNA gene copies/µl) and T. ovis (5.3 x 10 10 18s rRNA gene copies/µl).…”

Section: Hematological Assessmentmentioning

confidence: 99%

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A Comparative Study of Single Theileria Lestoquardi and Mixed Infections with Theileria Ovis

Al-Hamidhi

Elshafie

Morrison

et al. 2021

Preprint

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Background: Epidemiological surveys in Oman have revealed a high prevalence of the co-occurrence of the pathogenic T. lestoquardi and the non-pathogenic T. ovis among sheep in the Barka region, Oman. Our most recent data illustrated an interaction and reduced mortality risk in animals co-infected with T. lestoquardi and T. ovis, suggesting that the latter confers protection against pathogenicity of T. lestoquardi. The present study extends the above findings and examines disease outcomes; clinical markers, hematological parameters and parasite density in mixed and single T. lestoquardi infections. Methods: A total of 390 blood samples were collected from 16 sheep pens located in Barka, Oman between July and November 2019. Theileria spp were detected and quantified using qPCR assay targeting 18S rRNA, and the extent of genetic diversity was estimated by a panel of T. lestoquardi specific micro- and mini-satellites. The association of some disease markers with the presence of Theileria spp. and genetic diversity was tested. Results: Theileria spp were detected in 75 (19.2%) sheep; of these 65 (86.7%) had mixed infections (T. lestoquardi plus T. ovis), 8 (10.6%) were infected with T. lestoquardi alone and 2 (2.7%) with only T. ovis. Exotic breeds had a higher risk for Theileria spp infection. The density of both parasites was higher in single infection against mixed infection, and there was a relatively lower density of T. lestoquardi in mixed infections. However, there was no difference in hematological indices between single T. lestoquardi and mixed infections. High genetic diversity was observed among T. lestoquardi in Barka, with no differences of T. lestoquardi in single and mixed infections. The extent of diversity seen in Barka was higher (He = 0.772) than that reported in Oman in 2019 (He = 0.582), with distinct T. lestoquardi genotypes. Conclusion: The substantial prevalence of T. lestoquardi as mixed vs single infection supports the hypothesis that T. ovis confers protection against lethal T. lestoquardi infection. However, there were no differences in disease correlations (clinical markers, hematology parameters and density of parasites) or the extent of diversity of T. lestoquardi between the two types of infection. The presence of distinct T. lestoquardi genotypes in Barka, compared to that reported earlier in Oman, highlights the need for further analysis of the parasite populations to inform on novel approaches for controlling malignant theileriosis.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 91%