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Biomedical subjects

Ina L Smith

Publications and source records attributed to Ina L Smith.

9 recordsLinked to original sources
PubMed2006

Hendra virus infection in a veterinarian.

A veterinarian became infected with Hendra virus (HeV) after managing a terminally ill horse and performing a limited autopsy with inadequate precautions. Although she was initially only mildly ill, serological tests suggested latent HeV infection. Nevertheless, she remains well 2 years after her initial illness. Recently emerged zoonotic viruses, such as HeV, necessitate appropriate working procedures and personal protective equipment in veterinary practice.

Animals↗
PubMed2004

Detection of Australasian Flavivirus encephalitic viruses using rapid fluorogenic TaqMan RT-PCR assays.

The development of single, sensitive, fluorogenic reverse transcriptase-polymerase chain reaction (TaqMan) assays were required for the rapid and specific detection of three encephalitic viruses found in the Australasian region, namely; Japanese encephalitis virus (JEV), Murray Valley encephalitis virus (MVEV), and Kunjin virus (KUNV). Primers and a fluorogenic probe were individually designed to be complementary to a nucleotide region encompassing the 3' terminus of the nonstructural (NS) 5 gene and a portion of the 3' untranslated region (NS5-3'UTR) of each of the viral genomes respectively. Synthetically produced primer and probe controls were developed to minimize the likelihood of contamination and generation of false positives. Viral RNA from singly infected mosquitoes could be detected in pools of 1000 mosquitoes and positive mosquito pools collected from the field have been identified using each assay, indicating a high level of sensitivity and suitability for use in mosquito surveillance programs. In addition, the JEV TaqMan assay has been used to detect successfully viral RNA in sentinel pig serum samples. These assays potentially offer superior and timely detection of encephalitic viruses from surveillance samples, which is essential for the rapid implementation of vector control measures and continued monitoring of virus activity in the Australasian region.

Animals↗
PubMed2003

A molecular epidemiological study of Australian bat lyssavirus.

The genetic diversity of Australian bat lyssavirus (ABL) was investigated by comparing 24 ABL isolate glycoprotein (G) gene nucleotide sequences with those of 37 lyssaviruses representing Lyssavirus genotypes 1-6. Phylogenetic analyses indicated that ABL forms a monophyletic group separate from other lyssaviruses. This group differentiates into two clades: one associated with Pteropus (flying fox) species, the other with the insectivorous bat Saccolaimus flaviventris. Calculation of percentage nucleotide identities between isolates of the two clades revealed up to 18.7 % nucleotide sequence divergence between the two ABL variants. These observations suggest that ABL is a separate lyssavirus species with a similar epidemiology to chiropteran rabies virus (RV), where two distinct ABL variants co-exist in Australia in bat species with dissimilar ecology. Analyses of selection pressures in ABL G gene sequences provided some evidence of weak positive selection within the endodomain at amino acids 499 and 501, although in general the dominant evolutionary process observed was purifying selection. This intimates that, in nature, isolates of ABL, like those of RV, are subject to relatively strong selective constraints, suggesting a stability of host species, cell tropisms and ecological conditions.

Amino Acid Sequence↗
PubMed2003

Public health surveillance for Australian bat lyssavirus in Queensland, Australia, 2000-2001.

From February 1, 2000, to December 4, 2001, a total of 119 bats (85 Megachiroptera and 34 Microchiroptera) were tested for Australian bat lyssavirus (ABLV) infection. Eight Megachiroptera were positive by immunofluorescence assay that used cross-reactive ntibodies to rabies nucleocapsid protein. A case study of cross-species transmission of ABLV supports the conclusion that a bat reservoir exists for ABLV in which the virus circulates across Megachiroptera species within mixed communities.

Animals↗
PubMed2002

A quantitative PCR (TaqMan) assay for pathogenic Leptospira spp.

BACKGROUND: Leptospirosis is an emerging infectious disease. The differential diagnosis of leptospirosis is difficult due to the varied and often "flu like" symptoms which may result in a missed or delayed diagnosis. There are over 230 known serovars in the genus Leptospira. Confirmatory serological diagnosis of leptospirosis is usually made using the microscopic agglutination test (MAT) which relies on the use of live cultures as the source of antigen, often performed using a panel of antigens representative of local serovars. Other techniques, such as the enzyme linked immunosorbent assay (ELISA) and slide agglutination test (SAT), can detect different classes of antibody but may be subject to false positive reactions and require confirmation of these results by the MAT. METHODS: The polymerase chain reaction (PCR) has been used to detect a large number of microorganisms, including those of clinical significance. The sensitivity of PCR often precludes the need for isolation and culture, thus making it ideal for the rapid detection of organisms involved in acute infections. We employed real-time (quantitative) PCR using TaqMan chemistry to detect leptospires in clinical and environmental samples. RESULTS AND CONCLUSIONS: The PCR assay can be applied to either blood or urine samples and does not rely on the isolation and culture of the organism. Capability exists for automation and high throughput testing in a clinical laboratory. It is specific for Leptospira and may discriminate pathogenic and non-pathogenic species. The limit of detection is as low as two cells.

Blood Specimen Collection↗
PubMed2002

Sequence analysis of an isolate from a fatal human infection of Australian bat lyssavirus.

Australian bat lyssavirus (ABLV), which occurs in pteropid and insectivorous bat populations, causes a rabies-like encephalitis in infected humans. We report the first complete sequence of an ABLV isolate obtained from a human who developed symptoms 27 months after being bitten by an infected flying fox. This isolate is the smallest lyssavirus to be sequenced, with a size of 11,918 nucleotides. Analyses of previously unsequenced regions and the complete genome confirm its close relationship with classical rabies viruses. In addition, a leucine zipper-like motif, not present in the other lyssaviruses, was found in the conserved domain I of the polymerase protein. This is the first report of a lyssavirus to vary in an 11-nucleotide, strictly conserved, complementary terminal sequence. This region is thought to encode important cis-acting regulatory signals; ABLV variation indicates a greater degree of flexibility than was thought for lyssaviruses in this region. A comparison of the pteropid and insectivorous isolates of ABLV indicates considerable differences between the two viruses. If the divergence of the two occurred on the Australian mainland, ABLV may have been endemic to Australia well before European colonisation.

Adult↗
PubMed2002

Detection of Australian bat lyssavirus using a fluorogenic probe.

BACKGROUND: Australian bat lyssavirus (ABLV) has been transmitted to humans following a scratch or bite from an infected bat in two cases. Following a scratch or bite to a person, the bat is usually submitted for testing and diagnosis is made using a direct fluorescent antibody test on a brain smear. A nested RT-PCR assay has also been utilised to confirm diagnosis. If positive for lyssavirus, post-exposure prophylaxis is administered. OBJECTIVES: The TaqMan assay was developed to improve the diagnosis of ABLV infection, following problems encountered with the generation of spurious PCR products in the nested RT-PCR and also to reduce the high risk of contamination inherent with nested PCRs. STUDY DESIGN: RNA was extracted from 161 bat brains and the samples were compared using a conventional RT-PCR and the TaqMan based assay. Samples from a patient with an ABLV infection collected antemortem and postmortem were also tested. RESULTS: The sensitivity of the new TaqMan based PCR assay compared favourably with the nested PCR previously in use in our laboratory. This assay was able to detect RNA in samples collected antemortem and postmortem for the diagnosis of a human case of ABLV. CONCLUSIONS: The major advantage of the TaqMan based assay was the speed of diagnosis with a result within minutes of completing the PCR (a result within 4 h of receiving the specimen). This test greatly reduces the chance of false positives through the elimination of second-round PCR and the requirement for agarose gels. The assay is sensitive and specific and should be invaluable for future antemortem and postmortem diagnosis of ABLV infection in humans.

Animals↗