Project description:The protozoan parasite Theileria parva infects and transforms bovine lymphocytes inducing uncontrolled proliferation. The transforming schizont resides free in the host cell cytoplasm and it is assumed that proteins released from the parasite contribute to host cell transformation and parasite persistence. The identification and characterisation of parasite genes encoding candidate secreted proteins constitutes a first step towards elucidating this complex process. In earlier work, it was shown that the genes encoding subtelomere-encoded variable secreted proteins (SVSPs) are located at the subtelomeres of all four T. parva chromosomes and, with 85 members, form the largest Theileria gene family. The majority of predicted proteins contain signal peptides, suggesting secretion into the host cell cytoplasm. We analysed SVSP expression in T. parva-transformed cell lines established in vitro by infection of T or B lymphocytes with cloned T. parva parasites. Preliminary microarray followed by quantitative real-time PCR analysis revealed mRNA expression for a wide range of SVSP genes. The pattern of mRNA expression was neither influenced by the cell type transformed by T. parva, nor by the animal background. Instead, the pattern of SVSP mRNA expression was largely defined by the parasite genotype and found to be relatively stable when monitored in vitro over a period of two months. Experiments using antibodies raised against the SVSP TP03_0882 provided first evidence for protein expression. Interestingly, results indicate that SVSP expression in cell lines established from a cloned parasite is limited to only a small percentage of parasites, suggesting SVSP expression by individual parasites is restricted. Expression of epitope-tagged TP03_0882 in mammalian cells revealed nuclear translocation and localisation to different nuclear compartments, including nucleoli, nucleoplasm and other nuclear bodies. Nuclear translocation to the mammalian cell nucleus was shown to involve two different types of nuclear localisation signals present in the conserved C-terminal region of TP03_0882. This first characterisation, opens up possibilities for future studies on the regulation of gene expression and the biological role of these enigmatic proteins. Expression patterns of SVSP genes in different T. parva-infected cloned cell lines Keywords: Gene expression

Project description:The experiment investigates bovine gene expression in response to BW720c treatment in uninfected and Theileria annulata-infected cell cultures Theileria annulata, an intracellular parasite of bovine lymphoid cells, induces substantial phenotypic alterations to its host cell including continuous proliferation, cytoskeletal changes and resistance to apoptosis. While parasite induced modulation of host cell signal transduction pathways and NFκB activation are established, there remains considerable speculation on the complexities of the parasite directed control mechanisms that govern these radical changes to the host cell. Our objectives in this study were to provide a comprehensive analysis of the global changes to host cell gene expression with emphasis on those that result from direct intervention by the parasite. By using comparative microarray analysis of an uninfected bovine cell line and its Theileria infected counterpart, in conjunction with use of the specific parasitacidal agent, buparvaquone, we have identified a large number of host cell gene expression changes that result from parasite infection. Our results indicate that the viable parasite can irreversibly modify the transformed phenotype of a bovine cell line. 50% of genes with altered expression failed to show a reversible response to parasite death, a possible contributing factor to initiation of host cell apoptosis. The genes that did show an early predicted response to loss of parasite viability highlighted a sub-group of genes that are likely to be under direct control by parasite infection. Network and pathway analysis demonstrated that this sub-group is significantly enriched for genes involved in regulation of expression and chromatin modification. The results provide evidence that the Theileria parasite has the regulatory capacity to generate widespread change to host cell gene expression in a complex and reversible manner. Six experimental conditions with three replicates per condition. Total RNA prepared from cell cultures. BL20 (uninfected bovine lymphosarcoma cell line), BL20 24 hours post-BW720c treatment, BL20 48 hours post-BW720c, TBL (T. annulata infected bovine cell line), TBL 24 hours post-BW720c, TBL 48 hours post-BW720c. Each hydridisation represents bovine and parasite gene expression on a single channel and 2 technical replicates of each probeset are represented on the chip.

Project description:The protozoan parasite Theileria parva infects and transforms bovine lymphocytes inducing uncontrolled proliferation. The transforming schizont resides free in the host cell cytoplasm and it is assumed that proteins released from the parasite contribute to host cell transformation and parasite persistence. The identification and characterisation of parasite genes encoding candidate secreted proteins constitutes a first step towards elucidating this complex process. In earlier work, it was shown that the genes encoding subtelomere-encoded variable secreted proteins (SVSPs) are located at the subtelomeres of all four T. parva chromosomes and, with 85 members, form the largest Theileria gene family. The majority of predicted proteins contain signal peptides, suggesting secretion into the host cell cytoplasm. We analysed SVSP expression in T. parva-transformed cell lines established in vitro by infection of T or B lymphocytes with cloned T. parva parasites. Preliminary microarray followed by quantitative real-time PCR analysis revealed mRNA expression for a wide range of SVSP genes. The pattern of mRNA expression was neither influenced by the cell type transformed by T. parva, nor by the animal background. Instead, the pattern of SVSP mRNA expression was largely defined by the parasite genotype and found to be relatively stable when monitored in vitro over a period of two months. Experiments using antibodies raised against the SVSP TP03_0882 provided first evidence for protein expression. Interestingly, results indicate that SVSP expression in cell lines established from a cloned parasite is limited to only a small percentage of parasites, suggesting SVSP expression by individual parasites is restricted. Expression of epitope-tagged TP03_0882 in mammalian cells revealed nuclear translocation and localisation to different nuclear compartments, including nucleoli, nucleoplasm and other nuclear bodies. Nuclear translocation to the mammalian cell nucleus was shown to involve two different types of nuclear localisation signals present in the conserved C-terminal region of TP03_0882. This first characterisation, opens up possibilities for future studies on the regulation of gene expression and the biological role of these enigmatic proteins. Expression patterns of SVSP genes in different T. parva-infected cloned cell lines Keywords: Gene expression We performed a three-condition experiment comparing SVSP gene transcription in three T. parva infected cell lines: (1) 211T-A3 (consisting of CD4+ T cells), (2) 211B-A3 (consisting of B cells), and 951T-F44 (consisting of CD4+ T cells). We used direct two-color experiment design, comparing each cell line with the other, i.e. (1) 211T-A3 vs 211B-A3, (2) 211T-A3 vs 951T-F44 and (3) 211B-A3 vs 951T-F44. There were two biological replicates for each hybridization and dye-flips for each hybridization pair. Microarray consisted of four in-slide replicates peer gene as well as no-DNA spots as negative controls.

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Theileria parasites sequester host eIF5a to escape elimination by host-mediated autophagy

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Theileria parasites sequester host eIF5A to escape elimination by host-mediated autophagy.

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