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An insight into misidentification of the small-subunit ribosomal RNA (18S rRNA) gene sequences of Theileria spp. as Theileria annulata

Abstract

Background

There had been isolated reports of the presence of novel Theileria annulata genotypes based on the 18S rRNA gene sequence data from India, Pakistan and Saudi Arabia; but, these studies were restricted to limited field samples. Additionally, no comparative study has been conducted on all the isolates of this parasite from different countries whose sequences are available in the nucleotide databases. Therefore, we aimed to study the genetic diversity of T. annulata based on all available nearly complete 18S rRNA gene sequences in the GenBank™. Out of a total of 312 gene sequences of T. annulata available in the NCBI database, only 70 nearly complete sequences (> 1527 bp) were used for multiple sequence alignment.

Results

The maximum likelihood tree obtained using TN93 + G + I model manifested two major clades. All the valid host-cell transforming Theileria species clustered in one clade. The T. annulata designated sequences occupying this clade clustered together, excluding two isolates (DQ287944 and EU083799), and represented the true T. annulata sequences (n = 54). DQ287944 and EU083799 exhibited close association with Theileria lestoquardi. In addition, 14 Indian sequences formed a large monophyletic group with published Theileria orientalis sequences. The broad range of sequence identity (95.8–100%) of T. annulata designated sequences indicated the presence of different Theileria spp. A closer analysis revealed the presence of three Theileria spp., namely, T. annulata, T. orientalis, and two isolates (DQ287944 and EU083799) closely related to T. lestoquardi. The true T. annulata sequences manifested 98.8–100% nucleotide identity within them. EU083799 and 14 misidentified Indian T. annulata sequences exhibited the highest similarity with T. lestoquardi (98.6–98.8%) and T. orientalis (98.0-99.9%) in comparison with the other Theileria spp. of domestic and wild ruminants.

Conclusion

In the course of analyzing the genetic diversity of T. annulata, we identified the nearly complete 18S rRNA gene sequences of other Theileria spp. that have not only been misidentified as T. annulata in the GenBank™, but are also published as T. annulata. Moreover, a high level of sequence conservation was noticed in the 18S rRNA gene of true T. annulata and T. orientalis sequences.

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Background

Theileriosis is a tick-borne haemoprotozoan disease infecting a wide range of domestic and wild mammals. It has ubiquitous distribution due to the global existence of tick vectors [1]. There are many Theileria spp. that infect bovines; the most pathogenic and economically important are T. parva, which causes East Coast fever (ECF), T. annulata, which causes Tropical/ Mediterranean theileriosis, and T. orientalis (T. orientalis/buffeli group), which causes Oriental theileriosis or Theileria-associated bovine anaemia (TABA). Similarly, Theileria lestoquardi, which causes Malignant ovine theileriosis, Theileria uilenbergi and Theileria luwenshuni are the most pathogenic species of economic importance infecting small ruminants [1, 2]. Amongst the various diseases caused by the genus Theileria, bovine tropical theileriosis is an economically important disease of cattle and water buffaloes causing significant economic losses with several complications on both local and global scales [3,4,5]. It is caused by Theileria annulata, an intracellular apicomplexan parasite. The infected animals may present variable clinical symptoms, namely, fever, anemia, respiratory distress, jaundice, enlarged superficial lymph nodes, decreased milk yield, progressive loss of body weight, etc. [2]. The mild and subclinical infections are overlooked and animals remain carriers, but during stress conditions, the disease may flare up to a clinical state [6, 7]. The variable clinical presentation as well as irregular clinical signs and symptoms of the disease frequently noticed by the field veterinarians could be related to genetic changes in this protistan parasite [8], but this needs to be further investigated.

The different isolates of this apicomplexan parasite exhibit variable virulence in the susceptible bovine population in enzootic areas [9]. Additionally, the animals vaccinated with macroschizont attenuated cell culture vaccine developed from local isolates showed vaccination failures when challenged with a heterologous strain [10, 11], and it has been shown that such vaccines confer protection only against homologous isolates under field conditions [12]. Besides, the reduced efficacy of theilericidal drugs indicates emergence of drug resistant strains [13]. Taken together, all these attributes signify the presence of extensive genetic diversity in the said organism.

The commonly used genetic markers for T. annulata identification and characterization are the small-subunit ribosomal RNA (18S rRNA) gene [7, 14, 15], the T. annulata merozoites surface antigen (Tams1) encoding gene [16, 17], the β-tubulin gene [18], cytochrome b gene [19, 20] and the heat shock protein 70 encoding gene (HSP70) [21]. The 18S rRNA gene sequences have proven to be useful for deducing evolutionary patterns and are a widely used marker for genetic characterization, taxonomic classification and phylogenetic studies. It is used for determining species level infection of a number of parasites including T. annulata [22] and a number of sequences of different isolates from several parts of the world are freely available in the nucleotide databases for comparisons. The conserved and hypervariable (V4) regions of this gene are effectively studied and useful for elucidating relationships amongst different isolates and species [23]. The inter- and intra-species diversities can be estimated by the sequence and phylogenetic analyses based on this gene. There had been isolated reports of the presence of novel T. annulata genotypes based on the 18S rRNA gene sequence data from several countries, viz., India [24], Pakistan [25] and Saudi Arabia [26]; but, these studies were restricted to limited field samples. Additionally, no comparative study has been conducted on all the isolates of this parasite from different countries whose sequences are available in the nucleotide databases. Therefore, we aimed to study the genetic diversity of T. annulata based on all available nearly complete 18S rRNA gene sequences in the GenBank™. Further, an attempt was made to establish the phylogenetic relationship among all the sequences and with other species of the genus Theileria infecting domestic and wild ruminants.

Results

Phylogenetic analysis

Out of a total of 312 small-subunit ribosomal RNA gene sequences of T. annulata available in the database, only 70 nearly complete sequences (> 1527 bp) were used for multiple sequence alignment to construct a phylogenetic tree. The maximum likelihood tree obtained using TN93 + G + I model manifested two major clades (Fig. 1). All the valid host-cell transforming Theileria species (T. parva, T. annulata, T. lestoquardi and T. taurotragi) clustered in one clade. The T. annulata designated sequences occupying this clade revealed close association with T. lestoquardi (AF081135, China; AJ006446, Iran), T. parva (L02366, Kenya) and T. taurotragi (L19082, South Africa), which are all leucocyte transforming Theileria parasites. These T. annulata designated sequences clustered together, excluding two isolates (DQ287944 and EU083799), and represented the true T. annulata sequences. The Spanish (DQ287944, dog) and Chinese (EU083799) isolates exhibited close association with T. lestoquardi (AF081135, China; AJ006446, Iran).

Fig. 1
figure 1

The phylogenetic tree of different isolates of T. annulata with other Theileria species infecting domestic and wild ruminants based on nearly complete nucleotide sequences of  the nuclear 18S rRNA gene. Tamura-Nei model (TN93 + G + I) of maximum likelihood method was applied for this analysis. The taxon name of each sequence employed is depicted by its accession number followed by the place of sampling, if any, and the country of origin. The detail of accession numbers used is provided in supplementary Table 1. The color coding is done as mentioned below. Red font color with red filled circles as taxon markers- sequences that are correctly identified as T. annulata in the GenBank™ (shaded light red); blue font color with blue filled square as taxon marker- sequence deposited in the GenBank™ as T. annulata but is more closely related to T. lestoquardi (shaded light blue); pink font color with pink filled triangles as taxon markers- sequences deposited in the GenBank™ as T. annulata but are more closely related to T. orientalis (shaded light pink); Default font color without any taxon marker- rest of the sequences including outgroup

In addition, 14 nearly complete 18S rRNA sequences deposited in the GenBank™ as T. annulata shared a major clade with all the non-transforming Theileria species. They formed a large monophyletic group with published T. orientalis sequences from Australia (AB520953) and China (HM538195). Thus, these Indian sequences represent T. orientalis which have been misidentified as T. annulata in the GenBank™ and are published as T. annulata in two separate studies by Kundave et al. [14] and George et al. [24] as described in Table 1.

Table 1 List of misidentified 18S rRNA gene sequences of T. annulata recognized in the present study

Genetic diversity

The sequence identity in NCBI-BLAST showed that all the T. annulata designated sequences were 95.8–100% identical with each other, whereas 94.1–99.7% identical with the other Theileria species infecting ruminants. Sequence variations were detected in both conserved as well as in the hypervariable regions of the 18S rRNA gene at discrete places upon sequence alignment, indicating the presence of different parasite populations. A closer analysis revealed the presence of three distinct Theileria populations, namely, T. annulata, T. orientalis and two isolates (DQ287944 and EU083799) exhibiting close association with T. lestoquardi.

Theileria annulata

The 54 18S rRNA gene sequences of T. annulata originating from different countries, viz., India, China, Turkey and Iran, including the Iranian S15 vaccine strain (KF429795), manifested 98.8–100% nucleotide identity within them. In comparison with the other Theileria spp. infecting ruminants, they showed highest nucleotide identity (98.8–99.6%) with T. lestoquardi originating from China (AF081135) and Iran (AJ006446). The nucleotide variations within this group were recorded at 94 places throughout the alignment (Supplementary File 1).

Theileria orientalis

The 14 Indian small subunit ribosomal RNA sequences deposited in the GenBank™ as T. annulata but more closely related to T. orientalis, manifested 98–100% nucleotide identity amongst each other. On juxtaposition with the other Theileria spp. included in the study, they showed highest similarity (98.0–99.9%) with T. orientalis. The sequence variations were observed at 70 and 70–74 places within this group and when compared with the published T. orientalis sequences, respectively (Supplementary File 2).

Theileria lestoquardi like sequences

The only dog isolate of T. annulata (DQ287944, Spain) manifested 99.3% and 99.4% identity with T. lestoquardi of Iran (AJ006446) and China (AF081135), respectively; however, on additional amplification and sequencing of partial cytochrome b gene, it was confirmed to be T. annulata [27].

The 18S rRNA sequence of EU083799 (China) showed 98.6% and 98.8% identity with Iranian vaccine strain (AJ006446) and Chinese isolate (AF081135) of T. lestoquardi, respectively. It exhibited sequence variations at 22 places when compared with the vaccine strain of T. lestoquardi (AJ006446; Iran). The sequence and phylogenetic analyses suggest that it may be T. lestoquardi (Fig. 2).

Fig. 2
figure 2

Sequence variations detected in the conserved and hypervariable regions of the 18S rRNA gene upon multiple sequence alignment of T. lestoquardi like sequences. DQ287944 (Spain) and EU083799 (China) exhibited sequence variations at seven (marked # and shaded yellow) and 22 places (marked * and shaded orange) when compared with the vaccine strain of T. lestoquardi (AJ006446; Iran), respectively

The details of misidentified 18S rRNA gene sequences available in the GenBank™ as T. annulata and published as either T. annulata or T. orientalis are given in Table 1.

Discussion

The genetic characterization of T. annulata based on the 18S rRNA gene has been described by several workers from different parts of the globe [7, 14, 24, 25, 28, 29]. The 18S rRNA sequencing approach has been widely used to distinguish between apicomplexan and other eukaryotic species due to a high copy number of 18S rRNA molecules in the ribosomes, besides existence of the hypervariable regions within highly conserved DNA sequences [23]. These regions have been thoroughly studied and are critical in determining evolutionary patterns and similarity amongst Theileria species [22]. Simultaneously, this gene has been extensively used for molecular and phylogenetic analyses of several Theileria species infecting livestock [30, 31].

For developing new vaccines, diagnostics, drugs, and designing effective theileriosis control strategies, it is essential to investigate the genetic diversity of the causative agent [7]. The broad range of percent identity (95.8–100%) between 18S rRNA sequences deposited as T. annulata in the GenBank™ was not in agreement with the expected sequence identity within a Theileria species and suggested the presence of different parasite populations. However, this wide range of sequence identity was in correlation with Kundave et al. [14] and George et al. [24], but contrary to the percent identity scores of Khan et al. [25] and Sivakumar et al. [32]. It was because both of the former studies included the misidentified sequences of Theileria spp. as T. annulata. The high level of sequence conservation was identified within the true 18S rRNA gene sequences of T. annulata (98.8–100%) and T. orientalis (98–100%). It was not only consistent with the expected 18S rRNA sequence identity within a Theileria species, but also supported the findings of previous studies [8, 15, 25, 29, 32, 33]. Only 18S rRNA sequences longer than 1527 bp were used for sequence and phylogenetic analyses because it is difficult to differentiate the truncated 18S rRNA gene sequences of T. annulata and T. lestoquardi on the basis of partial sequences, and the phylogenies constructed with the long 18S rRNA sequences are characterized by high bootstrap support for clades [32, 34]. The presence of transforming Theileria species, viz., T. parva, T. annulata, T. lestoquardi and T. taurotragi, in one clade reinforced the previous finding that these species evolved from a common ancestor [35, 36]. Although the present study was aimed to analyze the genetic diversity of T. annulata, the results of phylogenetic and sequence analyses indicated the misidentification of Theileria spp. sequences as T. annulata in the GenBank™.

Molecular methods, viz., polymerase chain reaction (PCR) and sequencing, are very useful tools for species level identification of Theileria spp. [7, 28, 29, 37, 38]. However, an incorrect taxon identification can be made if the custom DNA sequences are not carefully analyzed and compared with the data available in public sequence databases. It becomes particularly important when the DNA shows high sequence identity between two or more parasites.

The 18S rRNA sequences of different Theileria species share high sequence identities between them due to recent speciation events [39]. Theileria lestoquardi is perhaps recently evolved from T. annulata and their 18S rRNA sequences share high percent identity between them. The V4 hypervariable region of the 18S rRNA gene of both the parasites differs from each other by only three nucleotides. Similarly, the 18S rRNA sequences of Theileria parva and Theileria sp. (buffalo) are highly conserved and differ by only 11 nucleotides [33]. This high level of sequence similarity can result in misannotation of the original sequences, as has been observed in the present study. To avoid misannotation of sequences, it is important to conduct an inter-species comparison among different Theileria species followed by an intra-species analysis based on the percent identity and sequence length, before depositing any 18S rRNA sequence of Theileria species in a nucleotide database [40].

While the Chinese 18S rRNA sequence EU083799 group most closely with other T. lestoquardi sequences, this does not confirm that this parasite is T. lestoquardi. Further, morphological, molecular and biological studies are required to confirm that this parasite is indeed T. lestoquardi.

As most of the existing detection methods based on the amplification of the 18S rRNA gene, viz., conventional and real-time PCR assays, reverse line blot hybridization and LAMP, for different Theileria species are based on the assumption that the region of this gene targeted by the primers and/or probes is conserved among all the members of a species [39]. So, with the presence of sequence variations in both conserved and hypervariable regions of the 18S rRNA gene within and between Theileria species, it needs to be ascertained whether these tests would correctly identify the different sequences and distinguish between the different species.

Although the 18S rRNA gene is undoubtedly a useful marker for defining Theileria species, it has been demonstrated that the 18S rRNA sequences alone are not definitive for species level identification of some Theileria species, viz., T. annulata and T. lestoquardi [32, 39], T. annulata and Theileria sp. Yokoyama [32], and T. parva and T. sp. (buffalo) [41]. Mans and co-workers [33] have provided evidence for the existence of intermediate 18S rRNA gene sequences between T. parva and T. sp. (buffalo). Therefore, exploratory analysis of both nuclear and mitochondrial genetic markers can be deemed essential for a clear demarcation between these closely related parasites. An additional genetic marker could not be included in the present study due to the non-availability of the sequences of the additional marker of the same field samples/isolates in the nucleotide databases, but this is a future prospective of this study. In addition, this analysis could also provide support for the existence of the genetic lineages in them.

The misidentification of a gene sequence of a parasite has a negative impact on the research community. The incorrectly annotated sequences of the 18S rRNA gene of Theileria spp. might be used by other researchers to identify the 18S rRNA sequences of new isolates or field samples, thus perpetuating the error. The results of the studies based on or involving misannotated sequences can be misleading. Therefore, the misidentification is to be avoided to avert its negative impact on the larger interests of researchers.

Conclusion

In the course of analyzing the genetic diversity of T. annulata, we identified the nearly complete 18S rRNA gene sequences of other Theileria spp. that have not only been misidentified as T. annulata in the GenBank™, but are also published as T. annulata. Moreover, a high level of sequence conservation was noticed in the 18S rRNA gene of true T. annulata and T. orientalis sequences.

Methods

Data collection

Out of a total of 3168 nucleotide sequences of the 18S rRNA gene of Theileria spp. available in the NCBI database (https://www.ncbi.nlm.nih.gov/nuccore) up to March, 2022, all the sequences of T. annulata (n = 312) were downloaded. Smaller and truncated sequences were removed from the analysis; only sequences having nearly complete sequence length of the 18S rRNA gene (> 1527 bp) corresponding to positions one and 1527 of T. annulata Uttar Pradesh 1 isolate (MF287945; India) at the start and end, respectively, were used for further study. Similarly, at least one representative sequence of the same gene of different Theileria species infecting domestic and wild ruminants, viz., Theileria lestoquardi, Theileria parva, Theileria taurotragi, Theileria ovis, Theileria cervi, Theileria capreoli, Theileria sinensis, Theileria buffeli, Theileria orientalis, Theileria luwenshuni, Theileria separata, Theileria uilenbergi, Theileria velifera and Theileria mutans, was retrieved from the GenBank™. The details of all the sequences along with their accession numbers used in the current study are depicted in supplementary Table 1.

Multiple sequence alignment and phylogenetic analysis based on the 18S rRNA gene

The sequences were aligned using multiple sequence alignment program MAFFT version 7 [42] and edited manually using BioEdit version 7.0.5.3 [43] as described by Nehra et al. [44], so that all the sequences started and ended at the homologous nucleotide positions. The multiple sequence alignments of the 18S rRNA gene sequences of different Theileria spp. were performed using MegAlign (DNASTAR) and BioEdit [43]. The nucleotide identities were computed using the ClustalW program of Lasergene 6.0 software [45].

Tamura-Nei model of maximum likelihood method was used for phylogenetic analysis and the best fit model of substitution was found to be TN93 + G + I [46]. The phylogenetic analysis of all nearly complete 18S rRNA sequences retrieved from the GenBank™ was performed using MEGA-X software version 10.1.7 [47]. The tree with the highest log likelihood (-6087.39) is shown. The percentage of trees in which the associated taxa clustered together is shown next to the branches. Initial tree(s) for the heuristic search were obtained automatically by applying Neighbor-Join and BioNJ algorithms to a matrix of pairwise distances estimated using the Maximum Composite Likelihood (MCL) approach, and then the topology was selected with superior log likelihood value. A discrete gamma distribution was applied with two categories (+ G, parameter = 0.16) and the rate variation model allowed 40.66% sites to be evolutionarily invariable. The tree was drawn to scale, with branch lengths measured in the number of substitutions per site. This analysis involved 87 nucleotide sequences with a total of 1564 positions in the final dataset. Babesia duncani (MH333111, USA) was used as an outgroup species for rooting (Fig. 1).

Availability of data and materials

The datasets generated and/or analyzed during the current study are available in the GenBank™ repository (https://www.ncbi.nlm.nih.gov/) and the accession numbers are listed in supplementary Table 1.

References

  1. Demessie Y, Samuel S. Tick borne hemoparasitic diseases of ruminants: a review. Adv Biol Res. 2015;9:210–24.

    CAS  Google Scholar 

  2. Bishop R, Musoke A, Morzaria S, Gardner M, Nene V. Theileria: intracellular protozoan parasites of wild and domestic ruminants transmitted by ixodid ticks. Parasitol. 2004;129:271–83.

    Article  Google Scholar 

  3. Ahmed J, Yin H, Schnittger L, Jongejan F. Ticks and tick-borne diseases in Asia with special emphasis on China. Parasitol Res. 2002;88(1):51–5.

    Article  Google Scholar 

  4. Elsify A, Sivakumar T, Nayel M, Salama A, Elkhtam A, Rizk M, Mosaab O, Sultan K, Elsayed S, Igarashi I, Yokoyama N. An epidemiological survey of bovine Babesia and Theileria parasites in cattle, buffaloes, and sheep in Egypt. Parasitol Int. 2015;64(1):79–85.

    Article  Google Scholar 

  5. Brown CGD. Dynamics and impact of tick-borne diseases of cattle. Trop Anim Health Prod. 1997;29:1–3S.

    Article  Google Scholar 

  6. Selim AM, Das M, Senapati SK, Jena GR, Mishra C, Mohanty B, Panda SK, Patra RC. Molecular epidemiology, risk factors and hematological evaluation of asymptomatic Theileria annulata infected cattle in Odisha, India. Iran J Vet Res. 2020;21(4):250.

    CAS  Google Scholar 

  7. Ullah R, Shams S, Khan MA, Ayaz S, Akbar NU, Din QU, Khan A, Leon R, Zeb J. Epidemiology and molecular characterization of Theileria annulata in cattle from central Khyber Pakhtunkhwa, Pakistan. PLoS ONE. 2021;16(9):e0249417.

    Article  CAS  Google Scholar 

  8. Amira AH, Ahmed L, Ahmed J, Nijhof A, Clausen PH. Epidemiological study on tropical theileriosis (Theileria annulata infection) in the egyptian Oases with special reference to the molecular characterization of Theileria spp. Ticks Tick Borne Dis. 2018;9(6):1489–93.

    Article  Google Scholar 

  9. Taylor LH, Katzer F, Shiels BR, Welburn SC. Genetic and phenotypic analysis of tunisian Theileria annulata clones. Parasitol. 2003;126:241–52.

    Article  CAS  Google Scholar 

  10. Gill BS, Bansal GC, Bhattacharyulu Y, Kaur D, Singh A. Immunological relationships between strains of Theileria annulata Dschunkowsky and Luhs 1904. Res Vet Sci. 1980;29:93–7.

    Article  CAS  Google Scholar 

  11. Subramanian G, Ray D, Naithani RC. In vivo culture and attenuation of macroschizonts of Theileria annulata (Duschunkowsky and Luhs, 1904) and in vivo use as vaccine. Indian J Anim Sci. 1986;56:174–82.

  12. Khatri N, Nichani AK, Sharma RD, Khatri M, Malhotra DV. Effect of vaccination in the field with the Theileria annulata (Hisar) cell culture vaccine on young calves born during the winter season. Vet Res Commun. 2001;25:179–88.

    Article  CAS  Google Scholar 

  13. Mhadhbi M, Chaouch M, Ajroud K, Darghouth MA, BenAbderrazak S. Sequence polymorphism of cytochrome b gene in Theileria annulata tunisian isolates and its association with buparvaquone treatment failure. PLoS ONE. 2015;10(6):e0129678.

    Article  Google Scholar 

  14. Kundave VR, Ram H, Shahzad M, Garg R, Banerjee PS, Nehra AK, Rafiqi SI, Ravikumar G, Tiwari AK. Genetic characterization of Theileria species infecting bovines in India. Infect Genet Evol. 2019;75:103962.

    Article  CAS  Google Scholar 

  15. Zeb J, Shams S, Din IU, Ayaz S, Khan A, Nasreen N, Khan H, Khan MA, Senbill H. Molecular epidemiology and associated risk factors of Anaplasma marginale and theileria annulata in cattle from North-western Pakistan. Vet Parasitol. 2020;279:109044.

    Article  CAS  Google Scholar 

  16. d’Oliveira C, Van Der Weide M, Habela MA, Jacquiet P, Jongejan F. Detection of Theileria annulata in blood samples of carrier cattle by PCR. J Clin Microbiol. 1995;33(10):2665–9.

    Article  Google Scholar 

  17. Kundave VR, Nehra AK, Ram H, Kumari A, Shahzad M, Vinay TS, Garg R, Banerjee PS, Singh G, Tiwari AK. Genetic diversity in the Tams1 gene of Theileria annulata (Duschunkowsky and Luhs, 1904) infecting cattle. Acta Trop. 2021;224:106121.

    Article  CAS  Google Scholar 

  18. Cacciò S, Cammà C, Onuma M, Severini C. The β-tubulin gene of Babesia and Theileria parasites is an informative marker for species discrimination. Int J Parasitol. 2000;30(11):1181–5.

    Article  Google Scholar 

  19. Parveen A, Ashraf S, Aktas M, Ozubek S, Iqbal F. Molecular epidemiology of Theileria annulata infection of cattle in Layyah District, Pakistan. Exp Appl Acarol. 2021;83(3):461–73.

    Article  CAS  Google Scholar 

  20. Parveen A, Alkhaibari AM, Asif M, Almohammed HI, Naqvi Z, Khan A, Aktas M, Ozubek S, Farooq M, Iqbal F. Molecular Epidemiology of Theileria annulata in cattle from two districts in Punjab (Pakistan). Animals. 2021;11(12):3443.

    Article  Google Scholar 

  21. Schnittger L, Shayan P, Biermann R, Mehlhorn H, Gerdes J, Ahmed JS. Molecular genetic characterization and subcellular localization of Theileria annulata mitochondrial heat-shock protein 70. Parasitol Res. 2000;86(6):444–52.

    Article  CAS  Google Scholar 

  22. Chaisi ME, Sibeko KP, Collins NE, Potgieter FT, Oosthuizen MC. Identification of Theileria parva and Theileria spp. (Buffalo) 18S rRNA gene sequence variants in the African Buffalo (Syncerus caffer) in southern Africa. Vet Parasitol. 2011;182:150–62.

    Article  CAS  Google Scholar 

  23. Hillis DM, Dixon MT. Ribosomal DNA: molecular evolution and phylogenetic inference. Q Rev Biol. 1991;66:411–53.

    Article  CAS  Google Scholar 

  24. George N, Bhandari V, Reddy DP, Sharma P. Molecular and phylogenetic analysis revealed new genotypes of Theileria annulata parasites from India. Parasit Vectors. 2015;8:1–8.

    Article  Google Scholar 

  25. Khan MK, He L, Hussain A, Azam S, Zhang WJ, Wang LX, Zhang QL, Hu M, Zhou YQ, Zhao J. Molecular epidemiology of Theileria annulata and identification of 18S rRNA gene and ITS regions sequences variants in apparently healthy buffaloes and cattle in Pakistan. Infect Genet Evol. 2013;13:124–32.

    Article  CAS  Google Scholar 

  26. Alanazi AD, Alouffi AS, Alshahrani MY, Alyousif MS, Abdullah HH, Allam AM, Elsawy BS, Abdel-Shafy S, Alsulami MN, Khan A, Iqbal F. A report on tick burden and molecular detection of tick-borne pathogens in cattle blood samples collected from four regions in Saudi Arabia. Ticks Tick Borne Dis. 2021;12:101652.

    Article  Google Scholar 

  27. Criado A, Martinez J, Buling A, Barba JC, Merino S, Jefferies R, Irwin PJ. New data on epizootiology and genetics of piroplasms based on sequences of small ribosomal subunit and cytochrome b genes. Vet Parasitol. 2006;142:238–47.

    Article  CAS  Google Scholar 

  28. Aparna M, Vimalkumar MB, Varghese S, Senthilvel K, Ajithkumar KG, Raji K, Syamala K, Priya MN, Deepa CK, Jyothimol G, Juliet S. Phylogenetic analysis of bovine Theileria spp. isolated in south India. Trop Biomed. 2013;30:281–90.

    CAS  Google Scholar 

  29. Habibi G. Phylogenetic analysis of Theileria annulata infected cell line S15 Iran vaccine strain. Iran J Parasitol. 2012;7:73–81.

    CAS  Google Scholar 

  30. Chae JS, Allsopp BA, Waghela SD, Park JH, Kakuda T, Sugimoto C, Allsopp MT, Wagner GG, Holman PJ. A study of the systematics of Theileria spp. based upon small-subunit ribosomal RNA gene sequences. Parasitol Res. 1999;85:877–83.

    Article  CAS  Google Scholar 

  31. Sivakumar T, Hayashida K, Sugimoto C, Yokoyama N. Evolution and genetic diversity of Theileria. Infect Genet Evol. 2014;27:250–63.

    Article  Google Scholar 

  32. Sivakumar T, Fujita S, Tuvshintulga B, Kothalawala H, Silva SSP, Yokoyama N. Discovery of a new Theileria sp. closely related to Theileria annulata in cattle from Sri Lanka. Sci Rep. 2019;9:1–10.

    Article  CAS  Google Scholar 

  33. Mans BJ, Pienaar R, Latif AA, Potgieter FT. Diversity in the 18S SSU rRNA V4 hyper-variable region of Theileria spp. in Cape buffalo (Syncerus caffer) and cattle from southern Africa. Parasitol. 2011;138:766–79.

    Article  CAS  Google Scholar 

  34. Chauhan RP, Kumari A, Nehra AK, Ram H, Garg R, Banerjee PS, Karikalan M, Sharma AK. Genetic characterization and phylogenetic analysis of Sarcocystis suihominis infecting domestic pigs (Sus scrofa) in India. Parasitol Res. 2020;119:3347–57.

    Article  Google Scholar 

  35. Allsopp MT, Cavalier-Smith T, De Waal DT, Allsopp BA. Phylogeny and evolution of the piroplasms. Parasitol. 1994;108:147–52.

    Article  CAS  Google Scholar 

  36. Lack JB, Reichard MV, Van Den Bussche RA. Phylogeny and evolution of the Piroplasmida as inferred from 18S rRNA sequences. Int J Parasitol. 2012;42:353–463.

    Article  CAS  Google Scholar 

  37. Gou H, Guan G, Ma M, Liu A, Liu Z, Xu Z, Ren Q, Li Y, Yang J, Chen Z, Yin H. Phylogenetic analysis of ruminant Theileria spp. from China based on 28S ribosomal RNA gene. Korean J Parasitol. 2013;51:511–7.

    Article  CAS  Google Scholar 

  38. Mohamed SB, Alagib A, AbdElkareim TB, Hassan MM, Johnson WC, Hussein HE, Taus NS, Ueti MW. Molecular detection and characterization of Theileria spp. infecting cattle in Sennar State, Sudan. Parasitol Res. 2018;117:1271–6.

    Article  Google Scholar 

  39. Mans BJ, Pienaar R, Latif AA. A review of Theileria diagnostics and epidemiology. Int J Parasitol Parasites Wildl. 2015;4:104–18.

    Article  Google Scholar 

  40. Nehra AK, Kumari A, Kundave VR, Vohra S, Ram H. Molecular insights into the population structure and haplotype network of Theileria annulata based on the small-subunit ribosomal RNA (18S rRNA) gene. Infect Genet Evol. 2022;99:105252.

    Article  CAS  Google Scholar 

  41. Bishop RP, Hemmink JD, Morrison WI, Weir W, Toye PG, Sitt T, Spooner PR, Musoke AJ, Skilton RA, Odongo DO. The african buffalo parasite Theileria. sp. (buffalo) can infect and immortalize cattle leukocytes and encodes divergent orthologues of Theileria parva antigen genes. Int J Parasitol Parasites Wildl. 2015;4(3):333–42.

    Article  CAS  Google Scholar 

  42. Katoh K, Rozewicki J, Yamada KD. MAFFT online service: multiple sequence alignment, interactive sequence choice and visualization. Brief Bioinform. 2019;20:1160–6.

    Article  CAS  Google Scholar 

  43. Hall TA. BioEdit. A user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucleic Acids Symp Ser. 1999;41:95–8.

    CAS  Google Scholar 

  44. Nehra AK, Kumari A, Moudgil AD, Vohra S. Phylogenetic analysis, genetic diversity and geographical distribution of Babesia caballi based on 18S rRNA gene. Ticks Tick Borne Dis. 2021;12:101776.

    Article  Google Scholar 

  45. Thompson JD, Higgins DG, Gibson TJ. CLUSTAL W: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position specific gap penalties and weight matrix choice. Nucleic Acids Res. 1994;22:4673–80.

    Article  CAS  Google Scholar 

  46. Tamura K, Nei M. Estimation of the number of nucleotide substitutions in the control region of mitochondrial DNA in humans and chimpanzees. Mol Biol Evol. 1993;10:512–26.

    CAS  Google Scholar 

  47. Kumar S, Stecher G, Li M, Knyaz C, Tamura K. MEGA X: Molecular evolutionary genetics analysis across computing platforms. Mol Biol Evol. 2018;35:1547–9.

    Article  CAS  Google Scholar 

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Acknowledgements

Authors are thankful to the worthy Vice-Chancellor and Director (Research), LUVAS, Hisar, for providing necessary facilities to carry out this work.

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Authors

Contributions

Anil Kumar Nehra: Conceptualization, Software, Writing- Reviewing and Editing and Supervision. Ansu Kumari: Writing- Original draft preparation, Investigation, Software and Methodology. Aman Dev Moudgil: Investigation and Methodology. Sukhdeep Vohra: Writing- Reviewing and Editing. The author(s) read and approved the final manuscript.

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Correspondence to Anil Kumar Nehra.

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Nucleotide sequence data reported in this paper are available in the GenBank™ database.

Supplementary Information

Additional file 1. Supplementary Table 1.

The details of T. annulata isolates/strains and Theileria species infecting domestic and wild ruminants originating from different countries used in sequence and phylogenetic analyses in the current study.

Additional file 2. Supplementary Fig. 1.

Circular phylogram of different T. annulata isolates with the other Theileria species based on nearly complete 18S rRNA gene sequences.

Additional file 3. Supplementary File 1:

Multiple sequence alignment of the nearly complete 18S rRNA gene sequences of true T. annulata isolates/ strains used in the sequence and phylogenetic analyses in the present study.

Additional file 4. Supplementary File 2:

Multiple sequence alignment of the nearly complete 18S rRNA gene sequences of T. orientalis group used in the sequence and phylogenetic analyses in the present study.

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Nehra, A.K., Kumari, A., Moudgil, A.D. et al. An insight into misidentification of the small-subunit ribosomal RNA (18S rRNA) gene sequences of Theileria spp. as Theileria annulata. BMC Vet Res 18, 454 (2022). https://doi.org/10.1186/s12917-022-03540-w

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Keywords

  • Theileria annulata
  • 18S rRNA
  • Misidentification
  • Theileria spp.
  • Genetic diversity
  • Sequence analysis