Vaccinia virus E3 protein is known to bind double-stranded RNA and mediate interferon resistance. Alanine scanning mutagenesis was performed on its dsRNA binding domain, sufficient for wild-type tropism and immune suppression in vitro, and dsRNA binding and host range function assayed. Residues involved in dsRNA binding were required for host range function; however, seven dsRNA binding mutants were unable to rescue ΔE3L replication. Utilizing recombinant viruses, non-rescue mutants were unable to inhibit protein Kinase R phosphorylation despite dsRNA binding. Furthermore, host range was found to correlate with cytokine suppression and replication in IFN stimulated Huh7R cells. Additionally, no direct association was found between dsRNA binding and PKR interaction, refining the suppression model. Novel protein-protein interactions were discovered between E3 and cellular proteins via differential gel electrophoresis. This study represents the first full mapping of E3 residues involved in dsRNA binding and tropism, forming a basis for future study.

The essay discusses judicial jurisdiction over workplace injury claims against a state in the former Soviet Union Countries. Claiming that such cases should be dismissed in foreign jurisdiction, the paper seeks explanation to different approach and different outcomes of workplace injury cases in the courts of the same countries. The essay begins with background information on particularities of unusual workplace injury cases which emerged in connection with important political event - collapse of the USSR. Relevant provisions of domestic and . international law on judicial jurisdiction, their interpretation and application in Commonwealth of Independent States are discussed in this paper. Analyzing provisions and reasons of different decisions, the essay infers the implications from analysis in support of its main claim.

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Vaccinia virus E3 protein is known to bind double-stranded RNA and mediate interferon resistance. Alanine scanning mutagenesis was performed on its dsRNA binding domain, sufficient for wild-type tropism and immune suppression in vitro, and dsRNA binding and host range function assayed. Residues involved in dsRNA binding were required for host range function; however, seven dsRNA binding mutants were unable to rescue ΔE3L replication. Utilizing recombinant viruses, non-rescue mutants were unable to inhibit protein Kinase R phosphorylation despite dsRNA binding. Furthermore, host range was found to correlate with cytokine suppression and replication in IFN stimulated Huh7R cells. Additionally, no direct association was found between dsRNA binding and PKR interaction, refining the suppression model. Novel protein-protein interactions were discovered between E3 and cellular proteins via differential gel electrophoresis. This study represents the first full mapping of E3 residues involved in dsRNA binding and tropism, forming a basis for future study.

In host defence, pattern recognition plays an essential role by enabling the immune system to discriminate self from pathogenic non-self. Pattern recognition is mediated by leukocyte expressed pattern recognition molecules (PRMs), which recognise pathogen associated molecular patterns (PAMPs) on pathogens. Phagocytosis is a critical event for anti-microbial defence and its contribution is not limited to the clearance and killing of pathogens, but extends to the activation of adaptive immunity through production of pro-inflammatory mediators and antigen presentation. Anti- fungal immunity is extremely efficient and operates via recognition, phagocytosis and killing of fungal pathogens by leukocytes. We have examined Dectin-1, a non-opsonic pattern recognition receptor that recognises live fungi and fungal derived particles and that is highly expressed on various leukocyte populations. We wanted to establish whether Dectin-1 contributes to anti-fungal defence by analysing various aspects of the receptor biology. Using both confocal microscopy and flow-cytometry, we demonstrate that Dectin-1 is a phagocytic receptor. Furthermore, using cell lines expressing receptor mutants, we show that this capacity is mediated by the membrane proximal tyrosine residue located in the ITAM-like motif. This makes Dectin-1 the first described phagocytic leukocyte expressed receptor for unopsonised fungi and fungal derived particles, and the first pattern recognition receptor that mediates phagocytic uptake through a tyrosine based motif. We demonstrate that the mechanisms by which Dectin-1 mediates cytoskeletal activation and actin polymerisation are novel, and not shared with the canonical IT AM containing Fc(gamma)Rs. In particular the observation that Syk kinase plays not role in Dectin- 1 mediated phagocytosis in macrophages. We show that Dectin-1 mediates cellular activation in response to zymosan particles and that these (beta)-glucan dependent biological effects require collaboration with toll-like receptors (TLRs) at the cell surface. We also show that ligand size determines intracellular receptor trafficking following internalisation. Furthermore, we show that when biologically active soluble glucans are internalised by Dectin-1, the receptor is retained intracellularly yet, when biologically silent glucans are used, Dectin-1 is recycled. Dectin-1 is thus established as both an important phagocytic fungal pattern recognition receptor with pro- inflammatory abilities and an additional tool with which to study the diversity of signalling processes associated with leukocyte expressed receptors.

Xenopus laevis injected with sheep erythrocytes (SRBC) at Stage 48 of Nieuwkoop and Faber (1967) showed no evidence of tolerance induction as a result of early exposure to antigen. These experiments showed that priming during the larval stages of development (at Stages 48 and 54 or at Stage 56) led to a positive anamnestic response when the animals were challenged after metamorphosis as toadlets. It was not, however, possible to demonstrate enhanced secondary responses within the larval period itself. The effect of the alkylating agent, cyclophosphamide on the generation of immunological memory varies at different stages of development. In the larva, positive memory cells generated at the time of priming may be the population most affected by the drug, whereas in adults the evidence suggests that suppressor cells may have been eliminated by the cyclophosphamide treatment. Cyclophosphamide had no tolerogenic effect when administered with a primary injection of SRBC even at larval Stage 48. It is concluded that, although transplantation tolerance to allografts has been demonstrated in Xenopus laevis, these free-living larvae are not vulnerable to tolerance induction by xenogeneic antigens. On the contrary, both HGG (human gamma globulin) and SRBC induce positive anamnesis in the larva which can be expressed post-metamorphosis. Tolerance was only observed in the present experiments to soluble antigen (HGG) injected in high doses, such as could induce tolerance in the adult as well as in tadpoles. In contrast to their ability to react to xenogeneic antigens with the induction of positive memory, larvae injected with live allogeneic cells (adult blood leucocytes) failed to produce any anamnestic response when challenged as toadlets. These cells, injected by various routes into larvae from Stage 47 to Stage 57 induced neither tolerance nor positive memory. The recipients responded in a primary manner both in mixed leucocyte reactions and to skin grafts.

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Although induction of innate immune responses during viral infection is essential, it can cause acute inflammation and lead to devastating results. The deleterious effect of innate immune responses has been demonstrated in gene therapy where administration of a replication deficient adenoviral vector (Ad) caused fatality during a clinical trial. Despite recent advances in our understanding of the innate immunity, there is a lack of understanding on how different cell types interact to mount inflammatory responses, which may play an important role in regulating immune responses in vivo. In this study, we investigated the interaction between macrophages and epithelial cells, the two major cell types capable of sensing and responding to viral infection in the airway, in induction of inflammatory responses against replication deficient Ads. We show in Chapter 2 that Ad infection of the macrophage-epithelial cell co-culture resulted in synergistic induction of inflammatory responses. Ad infection of the co-culture compared to macrophages alone resulted in higher cytotoxicity and induction of significantly higher levels of inflammatory mediators including pro-inflammatory cytokines, chemokines, nitric oxide, and reactive oxygen species. We found that these synergistic responses require macrophages and epithelial cells to be in close proximity suggesting that a novel mechanism regulates the inflammatory responses. In Chapter 3, we studied whether ATP plays a role in regulating inflammatory responses during acute Ad infection. Using the co-culture system, we found that ATP signaling through P2X7 receptor (P2X7R) is critical as inhibition or deficiency of P2X7R resulted in reduced inflammatory responses. We demonstrate that ATP-P2X7R signaling regulates inflammasome activation and IL-1β secretion. Furthermore, intranasal administration of Ad resulted in high mortality in mice but inhibition of ATP-P2X7R signaling enhanced survival and reduced inflammatory responses. These results suggest that ATP released by the infected cells plays an important role in regulating inflammatory responses during acute viral infection.