A novel retrovirus, morphologically consistent with mammalian C-type retroviruses, was detected by electron microscopy in mitogen-stimulated peripheral blood mononuclear cell cultures from 163 koalas and in lymphoma tissue from 3 koalas. PCR amplified provirus from the blood and tissues of 17 wild and captive koalas, and reverse transcriptase-PCR demonstrated viral mRNA, viral genomic RNA, and reverse transcriptase activity in koala serum and cell culture supernatants. Comparison of viral sequences derived from genomic DNA and mRNA showed identity indicative of a single retroviral species-here designated koala retrovirus (KoRV). Southern blot analysis of koala tissue genomic DNA using labelled KoRV probes demonstrated banding consistent with an endogenous retrovirus. Complete and apparently truncated proviruses were detected in DNA of both clinically normal koalas and those with hematopoietic disease. KoRV-related viruses were not detected in other marsupials, and phylogenetic analysis showed that KoRV paradoxically clusters with gibbon ape leukemia virus (GALV). The strong similarity between GALV and KoRV suggests that these viruses are closely related and that recent cross-host transmission has occurred. The complete proviral DNA sequence of KoRV is reported.

Gibbon ape leukaemia virus (GALV) and koala retrovirus (KoRV) share a remarkably close sequence identity despite the fact that they occur in distantly related mammals on different continents. It has previously been suggested that infection of their respective hosts may have occurred as a result of a species jump from another, as yet unidentified vertebrate host. To investigate possible sources of these retroviruses in the Australian context, DNA samples were obtained from 42 vertebrate species and screened using PCR in order to detect proviral sequences closely related to KoRV and GALV. Four proviral partial sequences totalling 2880 bases which share a strong similarity with KoRV and GALV were detected in DNA from a native Australian rodent, the grassland melomys, Melomys burtoni. We have designated this novel gammaretrovirus Melomys burtoni retrovirus (MbRV). The concatenated nucleotide sequence of MbRV shares 93% identity with the corresponding sequence from GALV-SEATO and 83% identity with KoRV. The geographic ranges of the grassland melomys and of the koala partially overlap. Thus a species jump by MbRV from melomys to koalas is conceivable. However the genus Melomys does not occur in mainland South East Asia and so it appears most likely that another as yet unidentified host was the source of GALV.

Simple SummaryWe designed a programme to control free-ranging kangaroos on a Queensland golf course, using contraceptive implants in females and vasectomisation or testicle removal in males. This reduced the numbers of pouch young to about one half of pre-intervention levels and controlled the population over a 2–4 year period. However, the necessary darting caused a mortality rate of 5–10% of captured animals, mainly due to complications before and after anaesthesia. It is concluded that population control is possible but careful management of kangaroos around the time of anaesthesia induction and recovery is important in such programmes to minimise losses.AbstractTraditionally, culling has been the expedient, most common, and in many cases, the only tool used to control free-ranging kangaroo populations. We applied a reproductive control program to a population of eastern grey kangaroos confined to a golf course in South East Queensland. The program aimed to reduce fecundity sufficiently for the population to decrease over time so that overgrazing of the fairways and the frequency of human–animal conflict situations were minimised. In 2003, 92% of the female kangaroos above 5 kg bodyweight were implanted with the GnRH agonist deslorelin after darting with a dissociative anaesthetic. In 2007, 86% of the females above 5 kg were implanted with deslorelin and also 87% of the males above 5 kg were sterilised by either orchidectomy or vasectomy. In 2005, 2008 and 2009, the population was censused to assess the effect of each treatment. The 2003 deslorelin program resulted in effective zero population growth for approximately 2.5 years. The combined deslorelin–surgery program in 2007 reduced the birth rate from 0.3 to 0.06%/year for 16 months, resulting in a 27% population reduction by November 2009. The results were consistent with implants conferring contraception to 100% of implanted females for at least 12 months. The iatrogenic mortality rates for each program were 10.5% and 4.9%, respectively, with 50% of all mortalities due to darting-related injuries, exertional myopathy/hyperthermia or recovery misadventure. The short term sexual and agonistic behaviour of the males was assessed for the 2007 program: no significant changes were seen in adult males given the vasectomy procedure, while sexual behaviours’ were decreased in adult males given the orchidectomy procedure. It is concluded that female reproduction was effectively controlled by implantation with deslorrelin and male reproductive behaviour was reduced by orchidectomy, which together achieved population control.

Analysis of genomic and expression data allows both identification and characterization of novel retroviruses. We describe a recombinant type C murine retrovirus, similar to the Mus dunni endogenous retrovirus, with VL30-like long terminal repeats and murine leukemia virus-like coding sequences. This virus is present in multiple copies in the mouse genome and expressed in a range of mouse tissues.Data mining genomic databases not only allows the discovery of new genes; it can also lead to the discovery and characterization of novel retroviruses and transposable elements and will prove invaluable in exploring the role of retroelements in host genome evolution. Here we combine analysis of both genomic and expression data to characterize a novel murine type C retrovirus from DNA sequence databases. This retrovirus is present in multiple copies in the Mus musculus genome, representing multiple recent insertions, and is transcribed in a range of mouse tissues. The virus is recombinant, with murine leukemia virus (MLV)-like coding sequences and long terminal repeats (LTRs) derived from a VL30 retroelement. Analysis of expression data suggests that a 70-bp repeat region of the LTR containing the polyadenylation signal can be tandemly duplicated and may have properties that enhance its cooption into the host genome.Complete simple type C retroviruses (accession no. AF151794 and X94150) were used as query sequences for searching the nonredundant high-throughput (HTG

In 1996, guidelines were produced for capture and radio-tracking protocols for koala (Phascolarctos cinereus) research within New South Wales (NSW). An integrated project commenced in 1998 to examine P. cinereus ecology and health status in Pine Creek State Forest. This project utilised intensive clinical and pathological assessment protocols on captured P. cinereus in combination with radio-tracking and ecological investigations. The methods used in this project were referred to the NSW Koala Research Committee (KRC) for review in mid 1999 due to the political profile of the study area. The KRC assessed the project protocols and reviewed the original guidelines incorporating some of the protocols used in the Pine Creek project. The outcome is a new set of protocols for P. cinereus research within NSW which are more explicit and restrictive than those applied to P. cinereus research elsewhere or to research on other species. In their current form the new guidelines require a substantial investment in time, equipment, personnel and finance; factors that may deter or restrict future, comprehensive ecological research on P. cinereus populations. They inadequately provide for some practices we believe important in minimising the invasiveness of P. cinereus capture. We propose amendments to the guidelines in the areas of personnel required, behavioural assessment, capture methods, processing safety and tracking frequency. We suggest that these amendments will render the guidelines more accessible to a broader range of projects, and easier to apply under field conditions while preserving the intent to maintain P. cinereus welfare and research best practice.