Structural Basis Of Influenza A Virus-specific CD8+ T Cell Receptor Diversity
Funder
National Health and Medical Research Council
Funding Amount
$469,500.00
Summary
Viral infection results in the activation and proliferation of virus-specific T cells that mediate clearance of virally infected cells. Recognition of virally infected cells is meditated by presentation of peptide fragments complexed to Major histocompatibility complex (MHC) class I glycoproteins. Virus-specific T cells recognise these viral protein fragments via a specific receptor expressed at the T cell surface. This proposal plans to examine the structural factors that determine influenza-sp ....Viral infection results in the activation and proliferation of virus-specific T cells that mediate clearance of virally infected cells. Recognition of virally infected cells is meditated by presentation of peptide fragments complexed to Major histocompatibility complex (MHC) class I glycoproteins. Virus-specific T cells recognise these viral protein fragments via a specific receptor expressed at the T cell surface. This proposal plans to examine the structural factors that determine influenza-specific T cell receptor recognition. From these studies, we plan to determine how these structural factors can influence the diversity of virus-specific T cells that are generated after viral infection. The conclusions from these studies will enable us to determine why some virus-specific T cell responses are not diverse and what are the consequences for virus-specific T cell immunity. This has implications for the development of novel vaccine strategies designed to induce immunity against both viral and tumour challenge.Read moreRead less
The immune system employs a variety of strategies to combat parasites including viruses. One of them is cytolytic lymphocytes, cells that can recognize and destroy virus-infected target cells. These cells use, besides other molecules, enzymes called granzymes to kill target cells by inducing suicide in them. We intend to investigate if those granzymes can protect cytolytic lymphocytes themselves from being infected by viruses and turned into viral factories. We are going to use a model of a natu ....The immune system employs a variety of strategies to combat parasites including viruses. One of them is cytolytic lymphocytes, cells that can recognize and destroy virus-infected target cells. These cells use, besides other molecules, enzymes called granzymes to kill target cells by inducing suicide in them. We intend to investigate if those granzymes can protect cytolytic lymphocytes themselves from being infected by viruses and turned into viral factories. We are going to use a model of a natural infection, ectromelia, mouse pox. Mouse pox is fatal in resistant strains of mice if the genes for the two dominant granzymes are deleted. This indicates that granzymes are essential for fighting this viral disease. We will explore in which cells of the immune system granzymes are expressed and whether virus entry into a cell can actually trigger their expression. Furthermore, we will investigate how the granzymes inhibit virus infection within the infected cell to determine whether the mechanisms involved resemble those used by cytolytic lymphocytes in killing of target cells (i.e. degradation of DNA and mitochondrial damage), or whether they represent entirely new facets of granzyme function. Finally, using viruses from a number of different families, we will establish whether these functions of granzymes also contribute to protection from other viral infections. An understanding of the role of these granzymes in the innate immune response, i.e. before antigen specific T cell and antibody responses are fully activated, is of great significance as it may allow us to manipulate this particular anti-viral response and thus enhance survival and reduce morbidity in viral infections.Read moreRead less
The Early Inflammatory Response To Virulent And Avirulent Influenza Viruses
Funder
National Health and Medical Research Council
Funding Amount
$252,761.00
Summary
Innate immune mechanisms are vital components of host defences against pathogens. In this proposal I aim to investigate the particular mechanisms that operate in early defence against influenza virus infection and compare the ability of virulent and avirulent virus strains to (i) be recognized by components of the innate immune system, and (ii) to trigger an early inflammatory response to infection. It is anticipated that virulent virus strains have adapted to avoid recognition by innate cells s ....Innate immune mechanisms are vital components of host defences against pathogens. In this proposal I aim to investigate the particular mechanisms that operate in early defence against influenza virus infection and compare the ability of virulent and avirulent virus strains to (i) be recognized by components of the innate immune system, and (ii) to trigger an early inflammatory response to infection. It is anticipated that virulent virus strains have adapted to avoid recognition by innate cells such as macrophages. By avoiding this route of uptake and destruction, the virus is free to infect and replicate in other cells of the respiratory tract. Furthermore, by evading macrophage entry, the virus avoids triggering the release of early inflammatory mediators from these cells and this may affect both the speed and the magnitude of the subsequent inflammatory response. This study will contribute to a greater understanding of factors involved in initiating and regulating inflammation in the respiratory tract following viral infection. Furthermore, the findings may provide new insights into mechanisms of virulence of influenza and other enveloped viruses.Read moreRead less
Immunodominance In Vaccinia Virus And Recombinant Vaccinia Vaccines
Funder
National Health and Medical Research Council
Funding Amount
$388,455.00
Summary
When confronted with an invading microbe, the human immune system does not recognise its overall shape. Instead, the microbe is chopped up into tiny fragments, called peptides, and these can be recognised by special cells of the immune system called T cells which orchestrate a response. We have a good understanding of this chopping process and can predict many of these peptides, but this is only part of the story. Not all peptides will be recognized by a T cell. Further, through processes we do ....When confronted with an invading microbe, the human immune system does not recognise its overall shape. Instead, the microbe is chopped up into tiny fragments, called peptides, and these can be recognised by special cells of the immune system called T cells which orchestrate a response. We have a good understanding of this chopping process and can predict many of these peptides, but this is only part of the story. Not all peptides will be recognized by a T cell. Further, through processes we do not understand well, T cells that recognize only a few out of the many peptides will dominate an entire immune response. As a result, immune responses are focused in such a way that they recognize only a tiny portion of an invading microbe. Focusing of immune responses also occurs during immunization with vaccines. Some new, genetically engineered vaccines use a harmless microbe to carry small parts of more dangerous pathogens. The parts chosen will not cause any disease by themselves, so the whole vaccine is safe. Vaccines built in this way are in clinical trials for diseases such as AIDS and malaria, but do not work as well as was hoped. These new vaccines are largely made up of the carrier and the parts of the microbe we wish to immunize against (e.g. a part of the AIDS virus) will be only a small fraction of the whole vaccine. Ideally we would like the immune system to focus on this small part of our choosing, but the few studies done suggest that this is not the case. In this project we will study vaccines that use a carrier called vaccinia virus. We will test to what extent immune responses are focused inappropriately. We will then genetically alter the virus and use new immunisation strategies to try and shift the focus of the immune response so that it targets the right parts of the vaccine. The ultimate aim is to improve vaccines, but in the process we may learn more about how the immune system chooses its targets.Read moreRead less
Role Of Plasmacytoid Dendritic Cells And Neutrophils In The Generation Of Antiviral Immunity
Funder
National Health and Medical Research Council
Funding Amount
$469,500.00
Summary
Work described in this application is important in understanding how two very different types of white blood cells, namely neutrophils and plasmacytoid dendritic cells (PDC), contribute to the generation of an effective immune response and control of virus growth. Both these cell types are activated in the earliest phase of the host response and are likely to play crucial roles in determining the nature of the later components of the response. We have recently shown that animals depleted of Gr-1 ....Work described in this application is important in understanding how two very different types of white blood cells, namely neutrophils and plasmacytoid dendritic cells (PDC), contribute to the generation of an effective immune response and control of virus growth. Both these cell types are activated in the earliest phase of the host response and are likely to play crucial roles in determining the nature of the later components of the response. We have recently shown that animals depleted of Gr-1+ cells, with monoclonal antibody (mAb) RB6-8C5, rapidly succumb to a poxvirus infection (mousepox) with 100% mortality. In contrast, mice treated with a control mAb clear the infection very effectively. Host responses essential for recovery from mousepox, including antiviral cytotoxic T lymphocyte (CTL) response and gamma interferon production, are severely diminished in mice treated with the Gr-1+ cell depleting mAb. Since the mAb can potentially deplete both neutrophils and PDC, this raises the important question of whether one or both of these cell types may be involved in the generation of cytokine and cell-mediated immune responses to viral infection. Although PDC and neutrophils themselves are not thought to present antigen to T cells, the elucidation of how they may control the generation of this major arm of the immune response will be novel and has important implications for vaccine design. Virtually nothing is known about how neutrophils or PDC influence viral antigen presentation by antigen presenting cells. Several murine models of viral infection, that in many ways mimic the diseases in humans, will be used to map the sequence of events initiated by PDC and neutrophils and which end in the clearance of virus from the host. Understanding these pathways and identifying the essential mediators and their interactions is critical in elucidating the role of the two cell types in the host response to virus infection.Read moreRead less
Defining The Molecular Effectors And Regulators Of Anti-viral Immune Responses
Funder
National Health and Medical Research Council
Funding Amount
$447,750.00
Summary
In humans, cytomegalovirus infection can cause severe disease and may even be fatal in individuals with immature or compromised immune systems, such as newborns, AIDS patients, transplant recipients and people treated with chemotherapeutic drugs. The majority of healthy individuals however can clear the infection with minimal disease. The ability of cytomegalovirus to cause disease is increased in the absence of effective immune responses which would normally clear the virus before illness occur ....In humans, cytomegalovirus infection can cause severe disease and may even be fatal in individuals with immature or compromised immune systems, such as newborns, AIDS patients, transplant recipients and people treated with chemotherapeutic drugs. The majority of healthy individuals however can clear the infection with minimal disease. The ability of cytomegalovirus to cause disease is increased in the absence of effective immune responses which would normally clear the virus before illness occurs. Understanding the role of specific mediators of anti-viral immune responses is therefore of paramount importance in establishing the guidelines for the design of more effective anti-viral therapies. The mouse model of cytomegalovirus infection provides a unique system to dissect the roles of specific components of the immune response during the course of viral infection. Our previous studies have shown that anti-viral immune responses are complex and involve a multitude of players. The central aim of the work in the current proposal is to establish the precise contribution of specific molecular effectors and regulators of anti-viral immune responses and define their relevance during the different stages of viral infection. Hence, the results of these studies will be relevant to understanding the pathogenesis of cytomegalovirus infection in humans and more importantly will provide critical insights into the rational design of improved antiviral drugs and vaccines. Since the molecules and cells under investigation are also known to play a crucial role in immune responses that control tumour growth and transplant survival, the proposed studies will provide valuable insight towards the development of new therapies for pathologies associated not only with cytomegalovirus infection, but also with the conditions named above.Read moreRead less
The Role Of RasGRP4, A Mast Cell Specific Protein In Mast Cell Growth, Differentiation And Activation
Funder
National Health and Medical Research Council
Funding Amount
$580,433.00
Summary
Mast cells are cells found in the body which are strategically located at mucosal sites and skin where they form a very important barrier in the immune defence. Mast cells have been implicated in a range of inflammatory disorders such as asthma and more recently they have been shown to participate in immunity against bacteria, viruses and fungi. Although a lot of work has been performed to analyze how mast cells respond to different stimuli and what factors are important in their activation, the ....Mast cells are cells found in the body which are strategically located at mucosal sites and skin where they form a very important barrier in the immune defence. Mast cells have been implicated in a range of inflammatory disorders such as asthma and more recently they have been shown to participate in immunity against bacteria, viruses and fungi. Although a lot of work has been performed to analyze how mast cells respond to different stimuli and what factors are important in their activation, there is little work available concerning what in the mast cell controls it's ability to become a mast cell and not any other cell. We have identified a specific protein that has been designated RasGRP4 which is restricted to mast cells and has, we believe, an important role to play not only in guiding immature cells to become mast cells but also in controlling some of the important functions of mast cells. Understanding this molecule more extensively will give us a much better understanding of diseases that the mast cell is involved in such as asthma and other inflammatory disorders. In addition it may shed insights into how mast cells are involved in immunity against bacteria and viruses.Read moreRead less
Development Of Novel Vaccine Strategies To Prevent Genital Tract Chlamydial Infection
Funder
National Health and Medical Research Council
Funding Amount
$408,556.00
Summary
Genital tract chlamydial infection is the most common bacterial sexually transmitted disease world wide with 4-5 million cases occurring annually throughout the world. The incidence of chlamydial infection is increasing in the Australian population. The majority of infections in women are asymptomatic and, if untreated, go on to cause pelvic inflammatory disease, ectopic pregnancy and infertility. These conditions can be life threatening and are a significant public health cost. In the proposal ....Genital tract chlamydial infection is the most common bacterial sexually transmitted disease world wide with 4-5 million cases occurring annually throughout the world. The incidence of chlamydial infection is increasing in the Australian population. The majority of infections in women are asymptomatic and, if untreated, go on to cause pelvic inflammatory disease, ectopic pregnancy and infertility. These conditions can be life threatening and are a significant public health cost. In the proposal we will develop novel vaccine strategies, involving both intranasal immunisation and immunisation by direct application to the skin, to induce protection against genital tract chlamydial infection. These studies will lay the basis for human trials of a vaccine to prevent what is now the most common STD in Australia. Such a vaccine to target this chronic infection would represent a major advance in preventive healthcare for the maintenance of good health.Read moreRead less
Human cytomegalovirus (HCMV) is a classic example of a group of herpes viruses, which is found universally throughout all geographic locations and socioeconomic groups, and infects 50% of adults in developed countries. HCMV infection is important to certain high-risk groups. Major areas of concern are: (1) the risk of infection to unborn baby during pregnancy, (2) the risk of infection to people who work with children, and (3) the risk of infection to immunocompromised persons (e.g. organ transp ....Human cytomegalovirus (HCMV) is a classic example of a group of herpes viruses, which is found universally throughout all geographic locations and socioeconomic groups, and infects 50% of adults in developed countries. HCMV infection is important to certain high-risk groups. Major areas of concern are: (1) the risk of infection to unborn baby during pregnancy, (2) the risk of infection to people who work with children, and (3) the risk of infection to immunocompromised persons (e.g. organ transplant patients and HIV-infected individuals). Epidemiological studies have shown that 80%-90% of developing unborn babies who acquire congenital HCMV infection displays a variable pattern of pathological sequelae within the first few years of life that may include hearing loss, vision impairment and mental retardation. There is an increasing argument that a reduction in HCMV load will have a significant effect on the sequelae associated with congenital HCMV infection. Indeed, vaccination provides the most practical modality of achieving such a reduction in HCMV load. To develop such a vaccine, formulation based on viral antigens that activate both protective cellular and humoral responses needs to be tested to assess its immunogenicity. No such vaccine is presently available for HCMV. In this application we have sought to develop a prophylactic vaccine and to test its efficacy in a immunocompetent transgenic mouse model and as well under conditions of immunosuppression (CD4 T cell deficient). The overall strategy is to use this prophylactic vaccine to stimulate the cellular (CD8+ and CD4+ T cells) and humoral responses against multiple HCMV antigens. This vaccine will be based on the novel chimeric polyepitope technology and exploits a novel replication deficient adenovirus expression system which has recently been approved for human use.Read moreRead less
Role Of The Natural Killer Complex In The Control Of Murine Malarial Pathogenesis
Funder
National Health and Medical Research Council
Funding Amount
$487,500.00
Summary
Natural Killer (NK )cells are an essential arm of the innate immune system. NK cell function is controlled by a series of cell surface receptors encoded within a defined genetic region named the Natural Killer Complex (NKC). This region appears to be highly polymorphic both in mice and humans. It is known that different mouse strains, which differ in the expression of NKC molecules have distinct ability to mount inflammatory responses during infection. In fact, we have previously shown that the ....Natural Killer (NK )cells are an essential arm of the innate immune system. NK cell function is controlled by a series of cell surface receptors encoded within a defined genetic region named the Natural Killer Complex (NKC). This region appears to be highly polymorphic both in mice and humans. It is known that different mouse strains, which differ in the expression of NKC molecules have distinct ability to mount inflammatory responses during infection. In fact, we have previously shown that the differential expression of NKC molecules in mice accounts for the degree of susceptibility to Plasmodium berghei-mediated cerebral malaria, a syndrome that accurately reproduces malarial disease induced by Plasmodium falciparum in humans and that results from an exacerbated pro-inflammatory response to infection. Since the NKC comprises several genes and multi-gene families, the main objective of this proposal is to identify which molecule-s within this genetic region are responsible for the induction of cerebral malaria pathogenesis. Our preliminary results indicate that an activation receptor named Ly49D, which is only expressed on the surface of NK cells from cerebral malaria-susceptible mice, plays a key role in disease-induction. Activation of Ly49D induces NK cells to secrete large amounts of IFN-gamma, a pro-inflammatory cytokine known to mediate cerebral-malaria pathogenesis. We will characterize the immunological function of Ly49D+ NK cells during P. berghei infection and determine whether these cells are the main source of IFN-gamma production. We will also identify the ligand (from parasite or host origin) responsible for the stimulation of this NKC activation receptor during malaria infection. The identification and characterization of these NKC receptors will provide new insights to explain the immunological basis of malarial pathogenesis and could lead to the development of therapeutical approaches designed to prevent severe malarial disease.Read moreRead less