The laboratory is located in the excellent facilities of the Medical Foundation Building, just adjacent to the main campus.

The interests of the laboratory are chiefly in understanding the mechanisms of severe malaria. Sometimes this work opens up new avenues of research that are not directly related to malaria, as in some of the projects listed below.

Laboratory-based projects

1. Expression of a newly-discovered enzyme in human tissues.

The laboratory’s research into the kynurenine pathway of tryptophan metabolism has led to the discovery of an important new enzyme associated with this pathway. The pathway metabolises tryptophan to a whole range of biologically active products and has been implicated in a number of physiological processes including regulation of blood pressure and reproduction. Changes to the pathway have been reported in important human diseases such as AIDS dementia, cerebral malaria and other neurological diseases.

The distribution of our newly-discovered enzyme in human tissues has not yet been discovered. To tackle this, the project will involve optimising an immunohistochemical approach to demonstrating the distribution of the enzyme in various human tissues. In this way, we can learn more about its functions in normal physiological processes and in disease states.

Supervisors: Professor Nick Hunt and Dr Helen Ball.

2. Expression and characterisation of a novel human enzyme.

We have cloned the enzyme mentioned above in the description of Project 1 in a bacterial system. We need to purify the enzyme from the culture medium and obtain it in a pure enough form to study its characteristics. For example, we will investigate its ability to breakdown certain substrates and find optimal conditions of pH, temperature and co-factors for activity.

This is vital in discovering more about the physiological role of the enzyme and in exploring the ability of certain agents to inhibit its activity, agents that later might be used for therapy of diseases.

Supervisors: Professor Nick Hunt and Dr Chris Austin.

3. Expression of indoleamine dioxygenase in response to Toll-like receptors in cell lines.

Indoleamine dioxygenase (IDO) is the first and rate-limiting enzyme in the kynurenine pathway of tryptophan metabolism. As described above, this pathway has important roles in normal physiology and in disease states.

Toll-like Receptors (TLRs) are associated with cells involved in innate immune responses. TLRs can recognise certain common patterns in infectious agents, allowing the rapid response of the immune system. IDO is an immunoregulatory molecule. However, the relationship between IDO and the TLRs has not been fully described.

In this project, you will expose cell lines obtained from the central nervous system to agonists of TLRs and evaluate the expression of the IDO gene by reverse transcription-polymerase chain reaction.

This project will reveal possible new interactions between different parts of the immune system.

Supervisors: Professor Nick Hunt and Dr Helen Ball.

4. Does modulation of the immune system determine the outcome of cerebral malaria?

Plasmodium berghei ANKA infection in mice leads to cerebral malaria. In contrast, infection with a related parasite strain, P. berghei K173, does not. We believe that this is because P. berghei K173 infection leads to the rapid production of immunomodulators in the spleen that “damp down” the subsequent immune response to prevent immunopathological complications due to an over-vigorous response.

A particular receptor molecule has been identified that is involved in regulation of dendritic cell function (important for antigen recognition) and T cell activation (important for immunity and also immunopathology). Laboratory investigators will obtain samples of brain, blood and spleen from mice with the gene encoding the receptor “knocked out” in order to investigate whether this affects the onset of cerebral malaria in P. berghei ANKA infection, or perhaps makes P. berghei K173 cause immunopathological responses when normally it does not. The tissue samples will be analysed by RT-PCR or a technique that measures cytokine levels, particularly in the spleen, in order to understand the outcomes of the experiment in terms of severe complications of malaria.

Supervisors: Dr Helen Ball and Professor Nick Hunt

Library-based project:

When the blood supply to tissues is restricted, they gradually lose energy and die. However, even quite short periods of such anoxia can damage tissues if the blood supply is suddenly re-established. This is called “ischaemia-reperfusion (I-R) injury.”

The mechanism of I-R injury is linked to the generation of so-called “free radicals”, in this case active forms of oxygen that can react with and damage tissues. The brain is an example of a tissue that is easily damaged by I-R.

In cerebral malaria, one mechanism of tissue injury that has been suggested is the blockage of blood vessels in the brain, possibly resulting in I-R injury. Thus the administration of agents that might inhibit such mechanisms could conceivably be of importance in treatment of cerebral malaria.

Many antioxidant compounds have been tested against I-R injury in the brain in experimental animal models of stroke. However, the results are quite varied. This library-based project will involve critically analysing the published literature on the effects of antioxidants on the outcome of I-R injury in the brain.

The topic is:

“Critically review the published literature on natural and artificial antioxidants as modifying agents in experimental rodent models of stroke.”

Supervisor: Professor Nick Hunt.

Address: Bosch Institute and Discipline of Pathology, level 1 Medical Foundation Building

Phone: 9036 3242

Email: nhunt@med.usyd.edu.au