Project description:Tropical theileriosis in a cattle disease of global economic importance, caused by the tick-borne protozoan parasite Theileria annulata. Conventional control strategies are failing to contain the disease and an attractive alternative is the use of pre-existing genetic resistance or tolerance. However, tropical theileriosis tolerant cattle are less productive than some susceptible breeds. To combine resistance and production traits requires an understanding of the mechanisms involved in resistance. Therefore, we have compared the response of monocytes derived from tolerant (Sahiwals, Bos indicus) and susceptible (Holstein-Friesians, B. taurus) cattle to in vitro infection with T. annulata. Over 150 genes exhibited breed-specific differential expression during the course of infection and nearly one third were differentially expressed in resting cells, implying that there are inherent differences between monocytes from the breeds. Fifty sequences currently only match ESTs or are unique to the library used to generate the microarray. The differential expression of a selection of genes was validated by quantitative RT-PCR, e.g. CD9, prion protein and signal-regulatory protein alpha. A large proportion of the differentially expressed genes encode proteins expressed on the plasma membrane or in the extracellular space and cell adhesion was one of the major Gene Ontology biological processes identified. We therefore hypothesise that the breed-specific tolerance of Sahiwal cattle compared to Holstein-Friesians is due to the interaction of infected cells with other immune cells, which influences the immune response generated against T. annulata infection. The BoMP microarray is available from the ARK-Genomics facility (www.ark-genomics.org).
Project description:Intracellular pathogens develop elaborate mechanisms to survive within the hostile environments of host cells. Theileria parasites infect bovine leukocytes and cause devastating diseases in cattle in developing countries. Theileria spp. have evolved sophisticated strategies to hijack host leukocytes, inducing proliferative and invasive phenotypes characteristic of cell transformation. Intracellular Theileria parasites secrete proteins into the host cell and recruit host proteins to induce oncogenic signaling for parasite survival. It is unknown how Theileria parasites evade host cell defense mechanisms, such as autophagy, to survive within host cells. Here, we show that Theileria annulata parasites sequester the host eIF5A protein to their surface to escape elimination by autophagic processes. We identified a small-molecule compound that reduces parasite load by inducing autophagic flux in host leukocytes, thereby uncoupling Theileria parasite survival from host cell survival. We took a chemical genetics approach to show that this compound induced host autophagy mechanisms and the formation of autophagic structures via AMPK activation and the release of the host protein eIF5A which is sequestered at the parasite surface. The sequestration of host eIF5A to the parasite surface offers a strategy to escape elimination by autophagic mechanisms. These results show how intracellular pathogens can avoid host defense mechanisms and identify a new anti-Theileria drug that induces autophagy to target parasite removal.
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.
Project description:Bovine tropical theileriosis is a major haemoprotozoan disease associated with high rates of morbidity and mortality particularly in exotic and crossbred cattle. It is one of the major constraints for of the livestock development programmes in India and southern Asia. Indigenous cattle (Bos indicus) are less affected by this disease than exotic and crossbred cattle. Genetic basis of resistance to tropical theileriosis in indigenous cattle is not well studied. Recent studies gives an idea that differentially genes expressed in exotic and indigenous breeds play an important role in breed specific resistance to tropical theileriosis. The present study was designed to visualize the global gene expression profiling in PBMCs derived from indigenous (Tharparkar) and crossbred cattle with in vitro infection of T. annulata. T. annulata Parbhani strain, originally isolated from Maharashtra (India) and maintained as cryopreserved stabilates of ground-up tick tissue sporozoite (GUTS) of infected H. anatolicum anatolicum was used as infective material. Two separate microarray experiments were carried out using separately each for crossbred and Tharparkar cattle. The crossbred cattle showed 1082 differentially expressed genes (DEGs). Out of total DEGs, 597 genes were downregulated and 485 were upregulated. Their fold change varies from 2283.93 to -4816.02. Tharparkar cattle showed 875 differentially expressed genes. Out of total DEGs in Tharparkar cattle, 451 genes were downregulated and 424 genes were upregulated. Their fold change varies from 94.93 to -19.20. A subset of genes was validated by quantitative RT-PCR and results correlated well with data obtained from the microarrays indicating that the microarray results gave an accurate report of transcript level. Functional annotation study of differentially expressed genes has confirmed their involvement in various pathways including response to oxidative stress, immune system regulation, cell proliferation, cytoskeletal changes, kinases activity and apoptosis. Gene network analysis of these differentially expressed genes provided an effective way to understand the interaction among them. It is therefore, hypothesised that the dissimilar susceptibility to tropical theileriosis exhibited by indigenous and crossbred cattle is due to breed-specific differences in the interaction of infected cells with other immune cells, which ultimately influences the immune response generated against T. annulata infection.