Antigen Dose And TCR Repertoire In CD8+ T Cell Immunodominance Hierarchies
Funder
National Health and Medical Research Council
Funding Amount
$558,920.00
Summary
The CD8+, or killer , T lymphocytes (white blood cells) are the hit men of immunity, recirculating continually around the body to eliminate other cells that are dangerous because they are cancerous or infected with a virus. A major difficulty is that killer T cells also exert selective pressures that cause viruses and tumours to mutate and thus avoid immune control. This is a particularly serious problem for RNA viruses that readily mutate as they divide. These include the human immunodeficiency ....The CD8+, or killer , T lymphocytes (white blood cells) are the hit men of immunity, recirculating continually around the body to eliminate other cells that are dangerous because they are cancerous or infected with a virus. A major difficulty is that killer T cells also exert selective pressures that cause viruses and tumours to mutate and thus avoid immune control. This is a particularly serious problem for RNA viruses that readily mutate as they divide. These include the human immunodeficiency virus (HIV) that causes AIDS and, while the mutations that are most important with influenza viruses are those that modify viral surface proteins recognized by antibodies, such T cell escape mutants can also be a problem with influenza. The other reason why there is particular interest in promoting CD8+ T cell-mediated immunity to influenza is that the killer T cells are very cross-reactive. We have shown that vaccination approaches that prime mouse CD8+ T cells to resist influenza A viruses circulating currently in humans will also protect against the highly lethal, and dangerous H5N1 bird 'flu. The present flu vaccines only stimulate antibodies, so there is interest in the possibility of a major re-design. The CD8+ T cells recognize tiny elements (peptides) of the virus or tumour bound in the tip of our own transplantation, or class I major histocompatibility complex (MHCI) molecules. These pMHCI complexes are called epitopes. The focus here is on the use of novel genetic engineering strategies to find out how, when the virus mutates to disrupt the major epitopes seen by killer T cells, other minor epitopes can be abnormally emphasized in a way that promotes effective immune control. As we work on this with the relatively simple and safe influenza model we will concurrently develop strategies that may be of value in HIV and tumour immunity. Solving this problem could prove to be a substantial advance in the design of vaccines and immunotherapy approaches.Read moreRead less
Systematically Exploring The Contribution Of Immunoproteasome To Immunodominance And T Cell Function
Funder
National Health and Medical Research Council
Funding Amount
$499,860.00
Summary
Vaccine will help us to fight both infectious diseases and malignancy. However, there are few successful vaccines for infectious agents and there is simply no vaccine to cure any tumor at the moment. So, it is essential for us to learn the basics related to vaccine development. Killer T cells eliminate tumour cells or virally infected host cells by recognising fragments (epitopes) derived from tumour- or virus-derived proteins displayed on a host molecule called MHC. Normally multiple epitopes a ....Vaccine will help us to fight both infectious diseases and malignancy. However, there are few successful vaccines for infectious agents and there is simply no vaccine to cure any tumor at the moment. So, it is essential for us to learn the basics related to vaccine development. Killer T cells eliminate tumour cells or virally infected host cells by recognising fragments (epitopes) derived from tumour- or virus-derived proteins displayed on a host molecule called MHC. Normally multiple epitopes are generated as part of the protein recycling program referred as proteine degradation which is mainly conducted by bundled enzyme complex, called proteasome. Two major forms of proteasomes are expressed by most cells. One called house-keeping proteasome and the other, which replaces the house-keeping one during viral infections is called immunoproteasome. The role that the immunoproteasome plays during anti-viral and anti-tumoral immune responses is not fully understood. In addition, the immunoproteasome is also expressed by a few cell types that do not suppose to need it if its function is entirely to generate better epitopes for MHC to display. In this project, we will sytematically explore the contribution of the immunoproteasome to overall anti-viral and anti-tumoral immune responses in three mouse model systems. The shared feature of these systems is that multiple killer T cell epitopes have been defined, which could potentially provide us with very sensitive assessments. The three systems are anti-influenza, anti-vaccinia virus and anti-tumor antigen (NY-ESO-1) mouse models.Read moreRead less
Host-virus Interactions That Define The Outcome Of Anti-viral T Cell Responses: Relevance To Viral Persistence
Funder
National Health and Medical Research Council
Funding Amount
$487,500.00
Summary
Infection with human cytomegalovirus (hCMV) is normally resolved without symptomatic evidence of infection. However, severe hCMV disease can occur in immunocompromised patients in which the manifestations of disease include chorioretinitis, interstitial pneumonia and hepatitis. In immunologically immature children, congenital infection results in cytomegalic inclusion disease (CID). CID in infants causes severe neurological sequelae resulting in mental retardation, deafness and blindness. Vaccin ....Infection with human cytomegalovirus (hCMV) is normally resolved without symptomatic evidence of infection. However, severe hCMV disease can occur in immunocompromised patients in which the manifestations of disease include chorioretinitis, interstitial pneumonia and hepatitis. In immunologically immature children, congenital infection results in cytomegalic inclusion disease (CID). CID in infants causes severe neurological sequelae resulting in mental retardation, deafness and blindness. Vaccination against hCMV induced cytomegalic inclusion disease has been designated Level I (most favourable) due to the prediction that it could save lives and prevent life-long disability. Given the essential nature of CD8 T cells in CMV control and the high prevalence of CMV in society, it will be crucial to develop a vaccine capable of eliciting an efficacious T cell response which develops lasting memory. We hypothesise that mCMV has evolved mechanisms for generating an appropriate T cell response involved in viral control and the establishment of a persistent infection. The central aim of the work in the current proposal is to investigate the cellular and viral mechanisms involved in the generation of cytomegalovirus specific T cells. The proposed studies will improve our understanding of the generation of anti-viral T cell responses and hence will be relevent to further our understanding of the role of T cells in human infection. More importantly the results will provide critical insights into the rational design of suitable antiviral drugs and vaccines.Read moreRead less
In Vivo Imaging Of Virus-specific T Cell Responses In The Skin
Funder
National Health and Medical Research Council
Funding Amount
$332,258.00
Summary
Effective vaccination against many viral infections such as Herpes Simplex Virus (HSV) may be achieved by directing the cells of the immune system to specific sites in the body where they can lie in wait against the disease. To direct the immune system in this way, we must first understand how immune cells orchestrate themselves in tissues. This project will utilise advanced imaging techniques to study immune cells in real time to understand how they protect against viral infections in the skin.
Determining The Role Of Rel/NF-kB Transcription Factors In CD8 T Cell Homeostasis.
Funder
National Health and Medical Research Council
Funding Amount
$426,500.00
Summary
NF-kB proteins comprise a family of transcription factors that regulate key genes involved in immune responses, inflammation, cell death and proliferation. This family of proteins are potential drug targets for treatment of various diseases. How and when such inhibitors are used in clinical situations depends on understanding how and which cells of the immune system are specifically affected by the absence of NF-kB proteins. In a number of treatment settings intercurrent viral infections occur f ....NF-kB proteins comprise a family of transcription factors that regulate key genes involved in immune responses, inflammation, cell death and proliferation. This family of proteins are potential drug targets for treatment of various diseases. How and when such inhibitors are used in clinical situations depends on understanding how and which cells of the immune system are specifically affected by the absence of NF-kB proteins. In a number of treatment settings intercurrent viral infections occur frequently and therefore there is an even greater need to understand how the immune system may be affected or compromised in response to the primary treatment. This work will provide insights into the cellular and molecular mechanisms affected by the absnece of a particular NF-kB family member (NF-kB1) in CD8 T cells during normal T cell homeostasis and when challenged with viruses. What we learn from our experiments could have important implications for the development of vaccines.Read moreRead less
The Role Of T Cell Receptor Avidity In Determining T Cell Repertoires And Responses
Funder
National Health and Medical Research Council
Funding Amount
$472,500.00
Summary
T cells are an essential component of the immune system. CD8 T cells, in particular, play a vital role in the immune response to viruses and tumors, predominantly via killing of virally infected cells and tumor cells, as well as the release of inflammatory mediators. T cells must be activated before they can mediate such anti-viral or anti-tumor effects and this activation occurs through the binding of pathogen or tumor fragments (peptides) by a receptor on the surface of T cells (T cell recepto ....T cells are an essential component of the immune system. CD8 T cells, in particular, play a vital role in the immune response to viruses and tumors, predominantly via killing of virally infected cells and tumor cells, as well as the release of inflammatory mediators. T cells must be activated before they can mediate such anti-viral or anti-tumor effects and this activation occurs through the binding of pathogen or tumor fragments (peptides) by a receptor on the surface of T cells (T cell receptor). Each individual has an entire repertoire of T cells with unique T cell receptors which interact with peptides with varying binding strengths. After stimulation of T cells by e.g. viral infection, a subset of the T cell repertoire will become expanded and dominate the anti-viral immune response. This study aims to investigate how, during a viral infection, the strength (or 'avidity') of the interaction between the T cell receptor and the peptide influences (i) whether or not a T cell clone is recruited into the immune response and, if so, its dominance over other clones within that response, and (ii) how efficiently a T cell is activated. It is anticipated that particular virus peptide-specific T cell populations with an overall high avidity will be better able to produce inflammatory mediators and kill infected cells compared to lower avidity T cell populations specific for a different virus peptide. It is also expected that the higher avidity populations will exhibit greater diversity of TCRs. Further, within peptide-specific populations, it is anticipated that the relatively high avidity T cell clones will dominate the specific response. This study will contribute to a greater understanding of factors contributing to T cell recruitment and activation. Armed with this knowledge we will be better able to design vaccines to elicit optimal T cell responses to viral infection.Read moreRead less