Altered immune parameters associated with Koala Retrovirus (KoRV) and Chlamydial infection in free ranging Victorian koalas (Phascolarctos cinereus)

Chlamydia is a significant pathogen for many species, including the much-loved Australian marsupial, the koala (Phascolarctos cinereus). To combat this situation, focused research has gone into the development and refinement of a chlamydial vaccine for koalas. The foundation of this process has involved characterising the immune response of koalas to both natural chlamydial infection as well as vaccination. From parallels in human and mouse research, it is well-established that an effective anti-chlamydial response will involve a balance of cell-mediated Th1 responses involving interferon-gamma (IFN-γ), humoral Th2 responses involving systemic IgG and mucosal IgA, and inflammatory Th17 responses involving interleukin 17 (IL-17) and neutrophils. Characterisation of koalas with chlamydial disease has shown increased expression within all three of these major immunological pathways and monitoring of koalas’ post-vaccination has detected further enhancements to these key pathways. These findings offer optimism that a chlamydial vaccine for wider distribution to koalas is not far off. Recent advances in marsupial genetic knowledge and general nucleic acid assay technology have moved koala immunological research a step closer to other mammalian research systems. However, koala-specific reagents to directly assay cytokine levels and cell-surface markers are still needed to progress our understanding of koala immunology.

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Optimising the short and long-term clinical outcomes for koalas (Phascolarctos cinereus) during treatment for chlamydial infection and disease

PLoS ONE ◽

10.1371/journal.pone.0209679 ◽

2018 ◽

Vol 13 (12) ◽

pp. e0209679 ◽

Cited By ~ 6

Author(s):

Amy Robbins ◽

Joanne Loader ◽

Peter Timms ◽

Jonathan Hanger

Keyword(s):

Clinical Outcomes ◽

Chlamydial Infection ◽

Phascolarctos Cinereus ◽

Short And Long Term

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Molecular Diagnosis of Koala Retrovirus (KoRV) in South Australian Koalas (Phascolarctos cinereus)

Animals ◽

10.3390/ani11051477 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1477

Author(s):

Tamsyn Stephenson ◽

Natasha Speight ◽

Wai Yee Low ◽

Lucy Woolford ◽

Rick Tearle ◽

...

Keyword(s):

South Australia ◽

Rna Seq ◽

High Complexity ◽

Phascolarctos Cinereus ◽

Viral Loads ◽

Lymphoid Neoplasia ◽

Central Regions ◽

Almost All ◽

Retroviral Infections ◽

Koala Retrovirus

Koala retrovirus, a recent discovery in Australian koalas, is endogenised in 100% of northern koalas but has lower prevalence in southern populations, with lower proviral and viral loads, and an undetermined level of endogenisation. KoRV has been associated with lymphoid neoplasia, e.g., lymphoma. Recent studies have revealed high complexity in southern koala retroviral infections, with a need to clarify what constitutes positive and negative cases. This study aimed to define KoRV infection status in Mount Lofty Ranges koalas in South Australia using RNA-seq and proviral analysis (n = 216). The basis for positivity of KoRV was deemed the presence of central regions of the KoRV genome (gag 2, pol, env 1, and env 2) and based on this, 41% (89/216) koalas were positive, 57% (124/216) negative, and 2% inconclusive. These genes showed higher expression in lymph node tissue from KoRV positive koalas with lymphoma compared with other KoRV positive koalas, which showed lower, fragmented expression. Terminal regions (LTRs, partial gag, and partial env) were present in SA koalas regardless of KoRV status, with almost all (99.5%, 215/216) koalas positive for gag 1 by proviral PCR. Further investigation is needed to understand the differences in KoRV infection in southern koala populations.

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Using non-invasive sampling methods to determine the prevalence and distribution of Chlamydia pecorum and koala retrovirus in a remnant koala population with conservation importance

Wildlife Research ◽

10.1071/wr17184 ◽

2018 ◽

Vol 45 (4) ◽

pp. 366 ◽

Cited By ~ 1

Author(s):

Faye Wedrowicz ◽

Jennifer Mosse ◽

Wendy Wright ◽

Fiona E. Hogan

Keyword(s):

Native Species ◽

Conservation Strategies ◽

The South ◽

Phascolarctos Cinereus ◽

Urogenital Infection ◽

Non Invasive ◽

Chlamydia Pecorum ◽

Genetic Sampling ◽

Pathogen Prevalence ◽

Koala Retrovirus

Context Pathogenic infections are an important consideration for the conservation of native species, but obtaining such data from wild populations can be expensive and difficult. Two pathogens have been implicated in the decline of some koala (Phascolarctos cinereus) populations: urogenital infection with Chlamydia pecorum and koala retrovirus subgroup A (KoRV-A). Pathogen data for a wild koala population of conservation importance in South Gippsland, Victoria are essentially absent. Aims This study uses non-invasive sampling of koala scats to provide prevalence and genotype data for C. pecorum and KoRV-A in the South Gippsland koala population, and compares pathogen prevalence between wild koalas and koalas in rescue shelters. Methods C. pecorum and KoRV-A provirus were detected by PCR of DNA isolated from scats collected in the field. Pathogen genetic variation was investigated using DNA sequencing of the C. pecorum ompA and KoRV-A env genes. Key results C. pecorum and KoRV-A were detected in 61% and 27% of wild South Gippsland individuals tested, respectively. KoRV-A infection tended to be higher in shelter koalas compared with wild koalas. In contrast with other Victorian koala populations sampled, greater pathogen diversity was present in South Gippsland. Conclusions In the South Gippsland koala population, C. pecorum is widespread and common whereas KoRV appears less prevalent than previously thought. Further work exploring the dynamics of these pathogens in South Gippsland koalas is warranted and may help inform future conservation strategies for this important population. Implications Non-invasive genetic sampling from scats is a powerful method for obtaining data regarding pathogen prevalence and diversity in wildlife. The use of non-invasive methods for the study of pathogens may help fill research gaps in a way that would be difficult or expensive to achieve using traditional methods.

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Prevalence of cryptococcal antigenemia and nasal colonization in a free-ranging koala population

Medical Mycology ◽

10.1093/mmy/myy144 ◽

2019 ◽

Vol 57 (7) ◽

pp. 848-857 ◽

Cited By ~ 7

Author(s):

Laura J Schmertmann ◽

Alex Kan ◽

Valentina S A Mella ◽

Cristina M Fernandez ◽

Mathew S Crowther ◽

...

Keyword(s):

Eucalyptus Camaldulensis ◽

Polymorphism Analysis ◽

Nasal Colonization ◽

Agar Culture ◽

Phascolarctos Cinereus ◽

South Wales ◽

Species Complexes ◽

Cryptococcus Spp ◽

Free Ranging ◽

The Relationship

AbstractCryptococcosis, caused by environmental fungi in the Cryptococcus neoformans and Cryptococcus gattii species complexes, affects a variety of hosts, including koalas (Phascolarctos cinereus). Cryptococcal antigenemia and nasal colonization are well characterized in captive koalas, but free-ranging populations have not been studied systematically. Free-ranging koalas (181) from the Liverpool Plains region of New South Wales, Australia, were tested for cryptococcal antigenemia (lateral flow immunoassay) and nasal colonization (bird seed agar culture). Results were related to environmental and individual koala characteristics. Eucalypt trees (14) were also randomly tested for the presence of Cryptococcus spp. by bird seed agar culture. In sum, 5.5% (10/181) and 6.6% (12/181) of koalas were positive for antigenemia and nasal colonization, respectively, on at least one occasion. And 64.3% (9/14) of eucalypts were culture-positive for Cryptococcus spp. URA5 restriction fragment length polymorphism analysis identified most isolates as C. gattii VGI, while C. neoformans VNI was only found in one koala and one tree. Colonized koalas were significantly more likely to test positive for antigenemia. No associations between antigenemia or colonization, and external environmental characteristics (the relative abundance of Eucalyptus camaldulensis and season), or individual koala characteristics (body condition, sex, and age), could be established, suggesting that antigenemia and colonization are random outcomes of host-pathogen-environment interactions. The relationship between positive antigenemia status and a relatively high abundance of E. camaldulensis requires further investigation. This study characterizes cryptococcosis in a free-ranging koala population, expands the ecological niche of the C. gattii/C. neoformans species complexes and highlights free-ranging koalas as important sentinels for this disease.

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Production of Milk and Nutrition of the Dependent Young of Free‐Ranging Koalas (Phascolarctos cinereus)

Physiological Zoology ◽

10.1086/515891 ◽

1998 ◽

Vol 71 (1) ◽

pp. 45-56 ◽

Cited By ~ 12

Author(s):

Andrew K. Krockenberger ◽

Ian D. Hume ◽

Steven J. Cork

Keyword(s):

Phascolarctos Cinereus ◽

Free Ranging

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