TFI012: Koalas in the Tilligerry & Tomaree Peninsulas of Port Stephens
Download the project sheet here.
Professor John Rodger
The project is an active collaboration with local koala carers and the two veterinarians whose practices service essentially all injured and sick koalas in the Tilligerry Pennisula and Nelson Bay areas. Koalas are difficult animals to access and very expensive to maintain because of the many hours involved in food collection. For this reason, facilitated access to a significant number of well cared for koalas, which are reasonably close to the University of Newcastle, is a boon to the project. Without this in kind contribution plus the expert veterinary care it would be virtually impossible to undertake the project. The involvement of Partners such as Pfizer, Port Stephens Council and Landcom as cash supporters is critical to building a viable level of cash leverage for the ARC linkage bid.
Koala populations in many regions are in decline under the twin pressures of habitat loss and disease caused by sexually transmitted Chlamydia. There is currently no vaccine therapy for koalas suffering from, or exposed to, this disease. Our collaborators (now at QUT) have successfully immunized mice with specific proteins from the surface of the Chlamydia bacterium (collectively called Chlamydia Antigens which protected against Chlamydia muridarum (mouse Chlamydia) in the lungs and reproductive systems.We propose to test whether a similar strategy is effective in the koala. A successful Chlamydia vaccine must invoke a sustained cellular and/or humoral immune response within the reproductive tract lining (the mucosa) which is the site of nfection. However, mucosal immunology and its manipulation remains a neglected area of marsupial biology. The project is unique in attempting to develop a protective Chlamydia vaccine for the oala and our group are the only ones in Australia working towards field appropriate vaccines for marsupials generally. The project is designed to have an impact locally, but if successful will be a significant advance for the conservation of the koala nationally.
This project will involve research on:
- The first large scale survey of the status of Chlamydia in a wild population by examining all oalas (and any dependant) young that come into care for what ever reason through the two collaborating Port Stephens veterinary practices.
- The development of the small laboratory-bred dunnart as a marsupial model for studies of Chlamydia, the mucosal immune response and anti-Chlamydia vaccine development at the University of Newcastle.
- The testing of an anti-Chlamydia vaccine in captive (Chlamydia-free) koalas at the Lone Pine sanctuary in Queensland.
Three Parallel Research Approaches to Vaccine Development are Proposed
This will involve short-term studies of koalas held in care to:
- Determine the Chlamydia status (by molecular techniques) of all koalas taken into care.
- Determine the Chlamydia status of pouch young of Chlamydia-positive mothers and the implications of this for understanding the mode of infection and its implication for vaccination strategies.
- Ascertain the level of Chlamydia-positive undiagnosed animals in the populations.
- Optimize assays for monitoring Chlamydia antigen-specific cellular and humoral (antibody) responses in the koala.
- Developing the Dunnart as a Model Species
Due to the limited access to, and iconic status of the koala, we are examing the potential of the mouse-like laboratory-bred fat-tailed dunnart (Sminthopsis crassicaudata) as an experimental model for studies about the fundamentals of Chlamydia infection and the development of protective vaccines for marsupials. Our initial studies using the technically attractive mouse Chlamydia (C. muridarum) were unsuccessful. Similar studies using the main Koala strain (C. pecorum) will be undertaken later this year. We are optimistic that one of the koala strains will infect the dunnart based on the large number of marsupial species in which Chlamydia has been detected. Experiments will involve:
- Monitoring infected animals for evidence of Chlamydia infection using Chlamydia-specific molecular assays
- Monitoring the progression of infection up the reproductive tract
- Examining the gross anatomy and histology of reproductive tracts for pathology
- Examining the fertility of Chlamydia infected dunnarts using natural mating and hormone manipulation as appropriate
- Investigating the potential of Chlamydia antigen vaccination to generate a site-specific (e.g. reproductive tract, respiratory tract and/or eye) and systemic humoral and cellular immune responses in the dunnart.
- Monitoring the effects of the vaccine on Chlamydia infected dunnarts.
- Testing an Anti-Chlamydia Vaccine in Koalas
Based on our Queensland collaborators early work it is expected that Koala Chlamydia-antigens will elicit an immune response in the oala and that this response could be protective. The first stage of the process of developing the vaccine is to first determine if such antigens elicit an immune response of the appropriate type to be protective in the koala, and that there are no significant unwanted side effects.
These experiments will involve:
- Producing the Koala specific Chalamydia antigens in bacteria and purifying the proteins.
- Injecting captive (Chlamydia-free) koalas at the Lone Pine sanctuary in Queensland with the antigens.
- Monitoring the cellular and humoral immune responses to the antigens.
- Monitoring the clinical status of the koalas for any adverse outcomes.
- Demonstrating that koala anti-chlamydia antibodies are protective in vitro (in vitro neutalization assay)