scholarly journals Isolation of infectious Theileria parva sporozoites secreted by infected Rhipicephalus appendiculatus ticks into an in vitro tick feeding system

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Rubikah Vimonish ◽  
Kelcey D. Dinkel ◽  
Lindsay M. Fry ◽  
Wendell C. Johnson ◽  
Janaina Capelli-Peixoto ◽  
...  
Keyword(s):  
Acute Infection ◽  
Rhipicephalus Appendiculatus ◽  
Theileria Parva ◽  
Feeding System ◽  
Tick Feeding ◽  
Global Food Security ◽  
Vector Borne Diseases ◽  
Infected Adult ◽  
Bovine Lymphocytes

Abstract Background Vector-borne diseases pose an increasing threat to global food security. Vaccines, diagnostic tests, and therapeutics are urgently needed for tick-borne diseases that affect livestock. However, the inability to obtain significant quantities of pathogen stages derived from ticks has hindered research. In vitro methods to isolate pathogens from infected tick vectors are paramount to advance transcriptomic, proteomic, and biochemical characterizations of tick-borne pathogens. Methods Nymphs of Rhipicephalus appendiculatus were infected with Theileria parva by feeding on a calf during an acute infection. Isolation of sporozoites was accomplished by feeding infected adult ticks on an in vitro tick feeding system. Sporozoite viability was tested using in vitro bovine lymphocytes. Results We isolated infectious T. parva sporozoites secreted into an in vitro tick feeding system. Infected adult R. appendiculatus ticks attached to and successfully fed on silicone membranes in the in vitro tick feeding system. Bovine blood in the receptacle was replaced with cell-free medium and the ticks were allowed to feed for 3 h to collect secreted T. parva sporozoites. Secreted sporozoites infected in vitro bovine lymphocytes, demonstrating that isolated sporozoites remained viable and infectious. Conclusions This work is the first to report the isolation of mature infectious T. parva sporozoites using an in vitro tick feeding system, which represents a significant step towards the development of a more efficient control strategy for T. parva. Isolation of infectious tick-stage parasites will facilitate the examination of the vector-pathogen interface, thereby accelerating the development of next-generation vaccines and treatment interventions for tick-borne pathogens. Graphical Abstract

scholarly journals Extensive Genotypic Diversity in a Recombining Population of the Apicomplexan Parasite Theileria parva

2006 ◽  
Vol 74 (10) ◽  
pp. 5456-5464 ◽  
Author(s):  
Frank Katzer ◽  
Daniel Ngugi ◽  
Chris Oura ◽  
Richard P. Bishop ◽  
Evans L. N. Taracha ◽  
...  
Keyword(s):  
Cytotoxic T Lymphocyte ◽  
Genotypic Diversity ◽  
Polymorphic Marker ◽  
Rhipicephalus Appendiculatus ◽  
Apicomplexan Parasite ◽  
Immune Recognition ◽  
Theileria Parva ◽  
Marker Analysis ◽  
Bovine Lymphocytes

ABSTRACT We evaluated sexual recombination in the apicomplexan parasite Theileria parva using genome-wide marker analysis of haploid sporozoite populations obtained from infected Rhipicephalus appendiculatus ticks. Analysis of 231 parasite clones derived by in vitro infection of bovine lymphocytes revealed 48 distinct combinations of 64 polymorphic marker loci. One genotype accounted for more than 75% of the clones, and the population was highly inbred with respect to this. The occurrence of frequent recombination was evident from reassortment of contiguous markers in blocks, with some recombination occurring within blocks. Analysis of four polymorphic loci encoding antigens targeted by protective cytotoxic-T-lymphocyte responses confirmed that these loci reassort, both within and between chromosomes, suggesting that recombination may influence immune recognition. Marker analysis of a panel of 142 clones derived from the population after an additional passage through a calf and the same tick colony revealed 18 genotypes, with the original dominant genotype accounting for 75% of the population and a higher level of inbreeding with respect to it in the remaining clones. Selected marker analysis of genomic DNA from these stabilates and the two preceding generations of the isolate, each derived from distinct tick colonies, revealed shifts in population structure with each generation, suggesting that the tick vector may impose nonrandom selective pressure on the parasite.

Comparison of manual and homogenizer methods for preparation of tick-derived stabilates of Theileria parva: equivalence testing using an in vitro titration model

Parasitology ◽  
2005 ◽  
Vol 131 (1) ◽  
pp. 45-49 ◽  
Author(s):  
V. MBAO ◽  
N. SPEYBROECK ◽  
D. BERKVENS ◽  
T. DOLAN ◽  
P. DORNY ◽  
...  
Keyword(s):  
East Coast ◽  
Treatment Method ◽  
Rhipicephalus Appendiculatus ◽  
Equivalence Testing ◽  
Theileria Parva ◽  
Control Option ◽  
Infected Adult ◽  
Effective Doses ◽  
Infection And Treatment Method

Theileria parva sporozoite stabilates are used in the infection and treatment method of immunization, a widely accepted control option for East Coast fever in cattle. T. parva sporozoites are extracted from infected adult Rhipicephalus appendiculatus ticks either manually, using a pestle and a mortar, or by use of an electric homogenizer. A comparison of the two methods as a function of stabilate infectivity has never been documented. This study was designed to provide a quantitative comparison of stabilates produced by the two methods. The approach was to prepare batches of stabilate by both methods and then subject them to in vitro titration. Equivalence testing was then performed on the average effective doses (ED). The ratio of infective sporozoites yielded by the two methods was found to be 1·14 in favour of the manually ground stabilate with an upper limit of the 95% confidence interval equal to 1·3. We conclude that the choice of method rests more on costs, available infrastructure and standardization than on which method produces a richer sporozoite stabilate.

Infection of mammalian cells with Theileria species

Parasitology ◽  
1983 ◽  
Vol 86 (2) ◽  
pp. 243-254 ◽  
Author(s):  
D. A. Stagg ◽  
A. S. Young ◽  
B. L. Leitch ◽  
J. G. Grootenhuis ◽  
T. T. Dolan
Keyword(s):  
Host Range ◽  
Mammalian Cells ◽  
Mammalian Species ◽  
Rhipicephalus Appendiculatus ◽  
Host Cells ◽  
Transformed Cells ◽  
Theileria Parva ◽  
African Buffalo

SUMMARYExperiments were carried out to determine the susceptibility of mammalian cells to infection with different species of Theileria in vitro. Sporozoites of Theileria parva (parva), Theileria parva (lawrencei) and Theileria taurotragi were isolated from Rhipicephalus appendiculatus ticks by grinding infected ticks in medium, filtering the suspension and concentrating by centrifugation. The sporozoites were used in attempts to infect in vitro peripheral blood leucocytes harvested from 16 different mammalian species which included 12 species of Bovidae from 6 different sub-families. The technique was shown to be both sensitive and reproducible. The sporozoites of T. parva (parva) infected and transformed cells from 2 species of the sub-family Bovinae, the two cattle types and African buffalo. Theileria parva (lawrencei) infected and transformed cells from the two cattle types, African buffalo and Defassa waterbuck. Theileria taurotragi sporozoites infected in vitro cells from 11 different species of Bovidae which were members of 6 sub-families; Bovinae, Tragelaphinae, Reduncinae, Alcelaphinae, Antilopinae and Caprinae. Transformed lymphoblastoid cell lines were established from 7 of the species infected. Sporozoite attachment and infection was not observed with non-susceptible bovid host cells, nor were any of the non-bovid leucocytes infected by the parasites. The host range observed in this study corresponded to the known host range in vivo.

Preliminary analysis of the transmission dynamics of Theileria parva in eastern Africa

Parasitology ◽  
1993 ◽  
Vol 106 (3) ◽  
pp. 251-264 ◽  
Author(s):  
G. F. Medley ◽  
B. D. Perry ◽  
A. S. Young
Keyword(s):  
Stable State ◽  
Ixodid Tick ◽  
Rhipicephalus Appendiculatus ◽  
Carrier State ◽  
Transmission Dynamics ◽  
Eastern Africa ◽  
Theileria Parva ◽  
Tick Feeding ◽  
Empirical Estimates ◽  
The Impact

SUMMARYTwo mathematical models are developed that investigate the transmission dynamics of Theileria parva by the ixodid tickRhipicephalus appendiculatus to cattle in endemically stable areas. A method of estimating the rate of infection to cattle ofT. parva at the endemically stable state is given. Empirical estimates of ail the parameters in the model are available. The degree to which animals that have recovered from theileriosis (the ‘carrier’ state) are able to transmit the infection to tick nymphs or larvae is a crucial determinant of the dynamics of infection in a herd. Two control methods influencing the transmission of infection are considered – infection and treatment immunization and the reduction in tick feeding by acaricide application. The impact of each method on the transmission of infection is evaluated. Future developments and the data required to predict the dynamics of T. parva infections in cattle and ticks are discussed.

Optimization of the in vitro feeding of Rhipicephalus appendiculatus nymphae for the transmission of Theileria parva

Parasitology ◽  
1995 ◽  
Vol 111 (4) ◽  
pp. 463-468 ◽  
Author(s):  
S. M. Waladde ◽  
A. S. Young ◽  
S. N. Mwaura ◽  
G. N. Njihia ◽  
F. N. Mwakima
Keyword(s):  
Rhipicephalus Appendiculatus ◽  
Artificial Feeding ◽  
Ixodid Ticks ◽  
Theileria Parva ◽  
Feeding Apparatus ◽  
Artificial Membrane ◽  
Feeding Performance ◽  
The Mean ◽  
In Vitro Feeding

SUMMARYAn apparatus for artificial feeding of Rhipicephalus appendiculatus nymphae was modified to improve feeding performance. Heparinized blood was supplied above a treated artificial membrane while the ticks attached below on its undersurface. The feeding apparatus was incubated at 37 °C in an atmosphere of 3% CO2 concentration and a relative humidity of 75–80%. Under these conditions, 91% of the engorged nymphae attained a mean weight of 6–11 mg, and an average of 93% of those nymphae moulted into adults. When this system was used to feed nymphal ticks on blood infected with Theileria parva piroplasms, the mean prevalence of infection in the resultant female and male ticks was 86% and 54%, respectively. The feeding performance and T. parva infection levels were comparable to those of nymphal ticks fed on the blood donor cattle. The apparatus used in this study has potential for modification to suit the artificial feeding needs of other species of ixodid ticks and for use in investigations to examine other tick/pathogen relationships.

scholarly journals South African Buffalo-Derived Theileria parva Is Distinct From Other Buffalo and Cattle-Derived T. parva

2021 ◽  
Vol 12 ◽  
Author(s):  
Boitumelo B. Maboko ◽  
Kgomotso P. Sibeko-Matjila ◽  
Rian Pierneef ◽  
Wai Y. Chan ◽  
Antoinette Josemans ◽  
...  
Keyword(s):  
South Africa ◽  
Genetic Diversity ◽  
South African ◽  
Variant Calling ◽  
Protozoan Parasite ◽  
Rhipicephalus Appendiculatus ◽  
Theileria Parva ◽  
African Buffalo ◽  
Illumina Hiseq

Theileria parva is a protozoan parasite transmitted by the brown-eared ticks, Rhipicephalus appendiculatus and Rhipicephalus zambeziensis. Buffaloes are the parasite’s ancestral host, with cattle being the most recent host. The parasite has two transmission modes namely, cattle–cattle and buffalo–cattle transmission. Cattle–cattle T. parva transmission causes East Coast fever (ECF) and January disease syndromes. Buffalo to cattle transmission causes Corridor disease. Knowledge on the genetic diversity of South African T. parva populations will assist in determining its origin, evolution and identify any cattle–cattle transmitted strains. To achieve this, genomic DNA of blood and in vitro culture material infected with South African isolates (8160, 8301, 8200, 9620, 9656, 9679, Johnston, KNP2, HL3, KNP102, 9574, and 9581) were extracted and paired-end whole genome sequencing using Illumina HiSeq 2500 was performed. East and southern African sample data (Chitongo Z2, Katete B2, Kiambu Z464/C12, Mandali Z22H10, Entebbe, Nyakizu, Katumba, Buffalo LAWR, and Buffalo Z5E5) was also added for comparative purposes. Data was analyzed using BWA and SAMtools variant calling with the T. parva Muguga genome sequence used as a reference. Buffalo-derived strains had higher genetic diversity, with twice the number of variants compared to cattle-derived strains, confirming that buffaloes are ancestral reservoir hosts of T. parva. Host specific SNPs, however, could not be identified among the selected 74 gene sequences. Phylogenetically, strains tended to cluster by host with South African buffalo-derived strains clustering with buffalo-derived strains. Among the buffalo-derived strains, South African strains were genetically divergent from other buffalo-derived strains indicating possible geographic sub-structuring. Geographic sub- structuring was also observed within South Africa strains. The knowledge generated from this study indicates that to date, ECF is not circulating in buffalo from South Africa. It also shows that T. parva has historically been present in buffalo from South Africa before the introduction of ECF and was not introduced into buffalo during the ECF epidemic.

Identification of Theileria infections in living salivary glands of ticks

Parasitology ◽  
1983 ◽  
Vol 86 (3) ◽  
pp. 519-528 ◽  
Author(s):  
A. S. Young ◽  
B. L. Leitch ◽  
B. L. Leitch ◽  
D. A. Stagg ◽  
T. T. Dolan
Keyword(s):  
Salivary Glands ◽  
Morphological Differentiation ◽  
Cell Types ◽  
Rhipicephalus Appendiculatus ◽  
Ixodid Ticks ◽  
Large Numbers ◽  
Infected Adult ◽  
Interference Contrast Microscopy ◽  
The Individual

SUMMARYIt was found that interference contrast microscopy gave good morphological differentiation of the living and intact salivary glands from adult ixodid ticks, Rhipicephalus appendiculatus and Amblyomrna variegatum, removed by dissection. In many cases the individual cell types of the acini could be recognized. When the salivary glands of infected adult ticks were examined Theileria parasites were detected. Theileria parva, T. taurotragi and T. mutans could be detected in the salivary glands after they reached the mature secondary sporoblast stage achieved even in unfed ticks. Parasites were detected only in type III acini. The morphology of tertiary sporoblasts and sporozoites of these Theileria spp. was clearly recognized in feeding ticks. Sporozoites of T. parva proved to be infective to cattle and to peripheral blood leucocytes of cattle in vitro after interference contrast examination. Interference contrast examination of living salivary glands was used for selection of salivary glands with high infections of T. parva sporozoites and the sporozoites could be separated in large numbers from these salivary glands. Using this technique it appeared possible to clone Theileria parasites from salivary glands with 1 infected acinus.

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