Genomic and phenotypic diversity of TunisianTheileria annulataisolates

Abstract

This study describes polymorphism in Theileria annulata, an intracellular protozoan parasite of bovine leucocytes and red blood cells. Fifty-three different stocks of T. annulata, isolated from 17 sites (districts) in Tunisia, have been characterized by anti-parasite monoclonal antibody (MAb) reactivity, glucose phosphate isomerase (GPI) isoenzyme electrophoresis, and Southern blotting with two genomic DNA probes. These appears to be considerable diversity amongst T. annulata stocks from Tunisia, no two isolates being identical, even those from animals on the same farm. Two distinct antigenic populations were detected by MAb 7E7. They were defined by negative and positive cells in the indirect fluorescent antibody test. The percentage of positive cells in different isolates ranged between 0 and 100%. The population variation seen by GPI analysis and DNA probes was greater; 7 different GPI phenotypes were identified amongst the stocks studied, while DNA probes T. annulata Tunis (TaT) 17 and 21 detected up to 5 different variants. The majority of isolates were shown to contain more than one parasite population, the number of variants per isolate ranging from 1 to 4. No correlation between particular parasite phenotypes or genotypes and their geographical site of isolation was observed. Selection of parasite populations in vivo and in vitro is also discussed.

Extensive Polymorphism and Evidence of Immune Selection in a Highly Dominant Antigen Recognized by Bovine CD8 T Cells Specific for Theileria annulata

“…Unlike the current experimental study, which utilized a cloned population of T. annulata for immunization (9), available evidence indicates that cattle in the field are often infected with genetically heterogeneous mixtures of parasites (4,63), which is likely to broaden the antigenic specificity of the CD8 T cell response and reduce the likelihood of breakthrough infections upon subsequent chal-lenge. However, the capacity to escape immune recognition may be of benefit to the parasite in field locations where parasite challenge is low and hence individual animals may be more likely to be infected with oligoclonal parasite populations.…”

A preliminary study on the attenuation of Tunisian schizont-infected cell lines of Theileria annulata

“…Characterisation of the T. annulata cell lines Two polymorphic markers were used to characterise the infected cell lines: the glucose phosphate isomerase (GPI) isoenzyme, which has been shown to detect seven alleles numbered 1-7, and the TaT 17 genomic probe, which can detect five genotypes numbered 1-5, according to the nomenclature described by Ben Miled et al (1994).…”

“…GPI isoenzyme electrophoresis and Southern blotting of DNA extracts with probe TaT 17 were undertaken according to the methods described by Melrose et al (1984) andBen Miled et al (1994), respectively. The characterisation was undertaken on parental and p100 CL1; parental, p100 and p200 CL2; parental, p100 and p200 CL 3; and parental CL4.…”

Population diversity of Theileria annulata in Portugal

“…A number of studies have shown considerable levels of genetic diversity in the T. annulata population using a variety of serological and molecular approaches (Ben Miled et al, 1994;Shiels et al, 1986;Gubbels et al, 2000;Schnittger et al, 2002;Weir et al, 2010). Population genetic studies of T. annulata have previously been performed using a panel of micro-and mini-satellite markers (Weir et al, 2007).…”