Population diversity of Theileria annulata in Portugal

Gomes, Jacinto; Salgueiro, Patrícia; Inácio, João; Amaro, Ana; Pinto, João; Tait, Andrew; Shiels, Brian; Fonseca, Isabel Pereira da; Santos‐Gomes, Gabriela; Weir, William

doi:10.1016/j.meegid.2016.04.023

Cited by 24 publications

(28 citation statements)

References 37 publications

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“…Genomic sequence analysis has allowed the identification of putatively neutral, polymorphic micro-and mini-satellite markers for economically important Theileria spp. which has facilitated population genetic analysis of T. parva (Oura et al, 2003) and T. annulata (Weir et al, 2007;Al-Hamidhi et al, 2015;Gomes et al, 2016) in a number of endemic regions. More recently, a set of genetic markers has been established for T. lestoquardi and, at present, only one Omani study has applied these markers to examining diversity in field populations of the parasite (Al-Hamidhi et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Theileria lestoquardi in Sudan is highly diverse and genetically distinct from that in Oman

Awad

Al-Hamidhi

Hussein

et al. 2018

Infection, Genetics and Evolution

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Malignant ovine theileriosis is a severe tick-borne protozoan disease of sheep and other small ruminants which is widespread in sub-Saharan Africa and the Middle East. The disease is of considerable economic importance in Sudan as the export of livestock provides a major contribution to the gross domestic product of this country. Molecular surveys have demonstrated a high prevalence of sub-clinical infections of Theileria lestoquardi, the causative agent, among small ruminants. No information is currently available on the extent of genetic diversity and genetic exchange among parasites in different areas of the country. The present study used a panel of T. lestoquardi specific micro- and mini-satellite genetic markers to assess diversity of parasites in Sudan (Africa) and compared it to that of the parasite population in Oman (Asia). A moderate level of genetic diversity was observed among parasites in Sudan, similar to that previously documented among parasites in Oman. However, a higher level of mixed-genotype infection was identified in Sudanese animals compared to Omani animals, consistent with a higher rate of tick transmission. In addition, the T. lestoquardi genotypes detected in these two countries form genetically distinct groups. The results of this work highlight the need for analysis of T. lestoquardi populations in other endemic areas in the region to inform on novel approaches for controlling malignant theileriosis.

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Section: Introductionmentioning

confidence: 99%

Theileria lestoquardi in Sudan is highly diverse and genetically distinct from that in Oman

Awad

Al-Hamidhi

Hussein

et al. 2018

Infection, Genetics and Evolution

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“…Studies of the global genetic sub-structure of T. annulata have shown a high level of genetic differentiation between Turkey and Tunisia (Weir et al, 2007). Studies have also shown a low level of genetic differentiation in T. annulata within-countries including Turkey, Tunisia, Oman, China and Portugal (Al-Hamidhi et al, 2015; Gomes et al, 2016; Weir et al, 2011; Yin et al, 2018), reflecting high levels of animal movement, or translocation of ticks.…”

Section: Discussionmentioning

confidence: 99%

Contrasting population genetics of cattle- and buffalo-derivedTheileria annulatacausing tropical theileriosis

Chaudhry¹,

Ali

Zheng

et al. 2020

Preprint

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The present study was designed to improve understanding of Theileria annulata in sympatric water buffalo and cattle in the Punjab province of Pakistan. The prevalence of tropical theileriosis is high, buparvaquone resistance is widespread, and vaccine protection is poor in the field. Better understanding is, therefore, needed of the factors that influence the genetics of T. annulata populations both within its hosts and in its overall populations. Here we utilise a panel of six satellites and a mitochondrial cytochrome b marker to explore the multiplicity of T. annulata infection and patterns of emergence and spread of different parasite genotypes. Parasite materials were collected from infected animals in defined regions, where water buffalo and cattle are kept together. Our results show that T. annulata is genetically more diverse in cattle- than in water buffalo-derived populations (the mean numbers of unique satellite alleles were 13.3 and 1.8 and numbers of unique cytochrome b locus alleles were 65 and 27 in cattle- and water buffalo-derived populations, respectively). The data show a high level of genetic diversity among the individual host-derived populations (the overall heterozygosity (He) indices were 0.912 and 0.931 in cattle, and 0.874 and 0.861 in buffalo, based on satellite and cytochrome b loci, respectively). When considered in the context of high parasite transmission rates and frequent animal movements between different regions, the predominance of multiple T. annulata genotypes, with multiple introductions of infection in the hosts from which the parasite populations were derived, may have practical implications for the spread of parasite genetic adaptations; such as those conferring vaccine cross-protection against different strains affecting cattle and buffalo, or resistance to antiprotozoal drugs.

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“…In the present study, a diverse range of parasite genotypes was identified in the vaccinated cattle over a disease season (Fig 2) and non-vaccinated animals at Day 105 of the sampling period (Fig 3B). Geographical sub-structuring at a large geographical scale has been documented between T. annulata populations in Tunisia, Turkey, Portugal and Oman (Al-Hamidhi et al, 2015;Gomes et al, 2016;Weir et al, 2007), but this has not been clearly demonstrated at the within-country level. In this study, a diverse range of parasite genotypes was observed in vaccinated animals on six different farms located within the same district (Fig 2).…”

Section: Discussionmentioning

confidence: 99%

“…Male and female gametes are formed which fuse to form zygotes, which in turn differentiate into kinetes that migrate to the salivary glands, ultimately generating bovine-infective sporozoites (Gauer, 1995;Schein and Friedhoff, 1978). Recent population genetic studies have provided further indirect evidence for the occurrence of a sexual phase in the parasite life cycle and these indicate that random mating is a feature of field populations of T. annulata (Al-Hamidhi et al, 2015;Gomes et al, 2016;Weir et al, 2007). Sexual recombination, together with a high transmission rate, is understood to play a significant role in generating T. annulata genetic diversity in different regions (Katzer et al, 2006;Pumpaibool et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…Recent field reports indicate an increasing number of 'breakthrough' cases in vaccinated animals (unpublished observation) and investigating the genetic basis of this phenomenon is now essential. Previous genetic analysis of T. annulata field populations using a panel of molecular markers has revealed a high level of genotypic diversity with large numbers of distinct parasite genotypes detected within limited geographical areas (Al-Hamidhi et al, 2015;Gomes et al, 2016;Weir et al, 2007;Yin et al, 2018). Furthermore, a previous study has indicated that the level of multiplicity of is influenced by vaccination status and that cell line vaccinated cattle tend to be infected with more genotypes than unvaccinated cattle (Weir et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Infection dynamics of Theileria annulata over a disease season following cell line vaccination

Bilgiç

Aksulu

Bakırcı

et al. 2019

Veterinary Parasitology

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Tropical theileriosis is a tick-borne haemoparasitic disease of cattle caused by the protozoan parasite Theileria annulata. Globally, the economic impact of the disease is immense and enhanced control measures would improve livestock production in endemic regions. Immunisation with a live attenuated vaccine is an effective and widely used control method, however, the repeated use of live vaccines may have an impact on the field parasite population at a genetic level. Additionally, there has been an increasing number of reports of vaccine breakthrough cases in recent years. Thus, the present study was designed to evaluate the genetic composition of a parasite population over a disease season in a locality where live cell line vaccination is practised. A diverse range of parasite genotypes was identified and every T. annulata positive cattle blood sample harboured multiple parasite genotypes. An alteration in the major genotype and an increasing multiplicity of infection in individual animals was observed over the course of the disease season. Vaccination status was found not to effect within-host multiplicity of infection, while a significantly higher number of genotypes was detected in grazed cattle compared to non-grazed ones. A degree of genetic isolation was evident between parasite populations on a micro-geographic scale, which has not been reported previously for T. annulata. Analysis of parasite genotypes in vaccinated animals suggested only a transient effect of the vaccine genotype on the genetic diversity of the T. annulata population. The vaccine genotype was not detected among clones of two vaccine 'breakthrough' isolates and there is no suggestion that it was responsible for disease. The obtained data indicated that in the system studied there is no apparent risk of introducing the vaccine genotype into the population with only a transient effect on the genetic diversity of the parasite population during the disease season.

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Population diversity of Theileria annulata in Portugal

Cited by 24 publications

References 37 publications

Theileria lestoquardi in Sudan is highly diverse and genetically distinct from that in Oman

Theileria lestoquardi in Sudan is highly diverse and genetically distinct from that in Oman

Contrasting population genetics of cattle- and buffalo-derivedTheileria annulatacausing tropical theileriosis

Infection dynamics of Theileria annulata over a disease season following cell line vaccination

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