Prevalence of koala retrovirus in geographically diverse populations in Australia.

OBJECTIVE: To determine the prevalence of koala retrovirus (KoRV) in selected koala populations and to estimate proviral copy number in a subset of koalas. METHODS: Blood or tissue samples from 708 koalas in Queensland, New South Wales, Victoria and South Australia were tested for KoRV pol provirus gene using standard polymerase chain reaction (PCR), nested PCR and real-time PCR (qPCR). RESULTS: Prevalence of KoRV provirus-positive koalas was 100% in four regions of Queensland and New South Wales, 72.2% in mainland Victoria, 26.6% on four Victorian islands and 14.8% on Kangaroo Island, South Australia. Estimated proviral copy number per cell in four groups of koalas from Queensland and Victoria showed marked variation, ranging from a mean of 165 copies per cell in the Queensland group to 1.29 × 10(-4) copies per cell in one group of Victorian koalas. CONCLUSIONS: The higher prevalence of KoRV-positive koalas in the north of Australia and high proviral loads in Queensland koalas may indicate KoRV entered and became endogenous in the north and is spreading southwards. It is also possible there are genetic differences between koalas in northern and southern Australia that affect susceptibility to KoRV infection or endogenisation, or that environmental factors affecting transmission in northern states are absent or uncommon in southern regions. Although further studies are required, the finding of proviral copy numbers orders of magnitude lower than what would be expected for the presence of a single copy in every cell for many Victorian animals suggests that KoRV is not endogenous in these animals and likely reflects ongoing exogenous infection.

Discovery of a novel murine type C retrovirus by data mining.

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.

Reduction of Walsh-transformed electrocardiograms by double logarithmic coding.

This work presents an electrocardiogram ECG data reduction method based on Walsh spectrum double logarithmic quantization. The technique is theoretically justified for a simulated ECG and its practical efficiency confirmed using MIT/BIH arrhythmia database signals. By classifying a "good" compression as one with MSE < or = 0.005 for 1:1 spectral reduction, a normal/abnormal ECG mix returned an 87% success rate for waveforms stored with 8- to 11-bit resolution.

The nucleotide sequence of koala (Phascolarctos cinereus) retrovirus: a novel type C endogenous virus related to Gibbon ape leukemia virus.

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.

Digital transmission of 12-lead electrocardiograms and duplex speech in the telephone bandwidth.

A system was developed which allowed the simultaneous communication of digitized, full duplex speech and electrocardiography (ECG) signals in realtime. A single band-limited channel was used over a standard telephone line providing 3 kHz bandwidth. The full duplex speech was compressed to 2400 bit/s using linear predictive coding, while multiple ECG signals were processed by a novel ECG compression technique. Extensive use of digital signal processing reduced the combined bit rate to less than 9600 bit/s, allowing the use of low-cost commercial modems. The ECG communications system was tested in clinical trials. It enabled a hospital-based clinician to provide diagnostic and treatment advice to a remote location over the standard telephone network.

Homologs of Mycobacterium leprae 18-kilodalton and Mycobacterium tuberculosis 19-kilodalton antigens in other mycobacteria.

Most of the antigens of Mycobacterium leprae and M. tuberculosis that have been identified are members of stress protein families, which are highly conserved throughout many diverse species. Of the M. leprae and M. tuberculosis antigens identified by monoclonal antibodies, all except the 18-kDa M. leprae antigen and the 19-kDa M. tuberculosis antigen are strongly cross-reaction between these two species and are coded within very similar genes. Studies of T cell reactivity against mycobacterial antigens have indicated that M. tuberculosis bears epitopes that are cross-reactive with the M. leprae 18-kDa antigen, but attempts to identify an 18-kDa antigen-like protein or protein coding sequence in M. tuberculosis have been unsuccessful. We have used a combination of low-stringency DNA hybridization and polymerase chain reaction techniques to identify, isolate, and sequence genes from M. avium and M. intracellulare that are very similar to the 18-kDa antigen gene of M. leprae and others that are homologs of the 19-kDa antigen gene of M. tuberculosis. Unlike M. leprae, which contains a single 18-kDa antigen gene, M. avium and M. intracellulare each have two 18-kDa antigen coding sequences. Although the M. leprae, M. avium, and M. intracellulare 18-kDa antigen genes are all very similar to one another, as are the M. tuberculosis, M. avium, and M. intracellulare 19-kDa antigen genes, we have been unable to detect any 18-kDa antigen-like coding sequences in DNA from M. tuberculosis.

Studies on hybridization between a Barbary ram (Ammotragus lervia) and domestic ewes (Ovis aries) and nanny goats (Capra hircus).

Six nanny goats and 9 ewes were inseminated with Barbary semen and 4-5 days after insemination 16 hybrid embryos were recovered: 14 were transferred to ewes or nanny goats. Survival of embryos was monitored by return to service after transfer, peripheral plasma progesterone values and by examination at laparotomy. None of the Barbary ram x ewe embryos transferred to 4 ewes and 4 nanny goats or the Barbary ram x nanny goat embryos transferred to ewes survived. Of the 4 nanny goat recipients of Barbary rm x nanny goat embryos one had a resorbed fetus at 7 weeks after transfer, one was pregnant at 7 weeks but failed to produce a young and a third produced a healthy male 155 days after the transfer oestrus. The karyotype of the hybrid was 2n = 59XY, characterized by a single metacentric chromosome.

An autosomal centric fusion translocation in the Red Poll breed in Australia.

The karyotype 2n = 59,XY,t:1/29 was found in two pure bred Red Poll bulls originating from stock imported from Britain. Orthodox stained and G-banded karyotypes of the condition in this breed are presented for the first time. Non-return rates for one bull suggest no impairment of fertility when selected for artificial insemination. However, in a related herd infertility has become a serious problem. It is suggested that selection pressure does not operate to eliminate the translocation and that caution should be exercised in the use of animals.