Paediatrics (RCH) - Research Publications
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ItemIdentification of a novel picornavirus related to cosaviruses in a child with acute diarrhea(BMC, 2008-12-22)Diarrhea, the third leading infectious cause of death worldwide, causes approximately 2 million deaths a year. Approximately 40% of these cases are of unknown etiology. We previously developed a metagenomic strategy for identification of novel viruses from diarrhea samples. By applying mass sequencing to a stool sample collected in Melbourne, Australia from a child with acute diarrhea, one 395 bp sequence read was identified that possessed only limited identity to known picornaviruses. This initial fragment shared only 55% amino acid identity to its top BLAST hit, the VP3 protein of Theiler's-like virus, suggesting that a novel picornavirus might be present in this sample. By using a combination of mass sequencing, RT-PCR, 5' RACE and 3' RACE, 6562 bp of the viral genome was sequenced, which includes the entire putative polyprotein. The overall genomic organization of this virus was similar to known picornaviruses. Phylogenetic analysis of the polyprotein demonstrated that the virus was divergent from previously described picornaviruses and appears to belong to the newly proposed picornavirus genus, Cosavirus. Based on the analysis discussed here, we propose that this virus represents a new species in the Cosavirus genus, and it has tentatively been named Human Cosavirus E1 (HCoSV-E1).
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ItemMetagenomic analysis of human diarrhea: Viral detection and discovery(PUBLIC LIBRARY SCIENCE, 2008-02)Worldwide, approximately 1.8 million children die from diarrhea annually, and millions more suffer multiple episodes of nonfatal diarrhea. On average, in up to 40% of cases, no etiologic agent can be identified. The advent of metagenomic sequencing has enabled systematic and unbiased characterization of microbial populations; thus, metagenomic approaches have the potential to define the spectrum of viruses, including novel viruses, present in stool during episodes of acute diarrhea. The detection of novel or unexpected viruses would then enable investigations to assess whether these agents play a causal role in human diarrhea. In this study, we characterized the eukaryotic viral communities present in diarrhea specimens from 12 children by employing a strategy of "micro-mass sequencing" that entails minimal starting sample quantity (<100 mg stool), minimal sample purification, and limited sequencing (384 reads per sample). Using this methodology we detected known enteric viruses as well as multiple sequences from putatively novel viruses with only limited sequence similarity to viruses in GenBank.
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ItemKlassevirus 1, a previously undescribed member of the family Picornaviridae, is globally widespread(BMC, 2009-06-24)BACKGROUND: Diarrhea is the third leading infectious cause of death worldwide and is estimated to be responsible for approximately 2 million deaths a year. While many infectious causes of diarrhea have been established, approximately 40% of all diarrhea cases are of unknown etiology. In an effort to identify novel viruses that may be causal agents of diarrhea, we used high throughput mass sequencing to analyze stool samples collected from patients with acute diarrhea. RESULTS: Sequences with limited similarity to known picornaviruses were detected in a stool sample collected in Australia from a child with acute diarrhea. Using a combination of mass sequencing, RT-PCR, 5' RACE and 3' RACE, a 6383 bp fragment of the viral genome was sequenced. Phylogenetic analysis demonstrated that this virus was highly divergent from, but most closely related to, members of the genus Kobuvirus. We have tentatively named this novel virus klassevirus 1. We also detected klassevirus 1 by RT-PCR in a diarrhea specimen collected from a patient in St. Louis, United States as well as in untreated sewage collected in Barcelona, Spain. CONCLUSION: Klassevirus 1 is a previously undescribed picornavirus that is globally widespread and present on at least three continents. Further investigations to determine whether klassevirus 1 is a human pathogen are needed.
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ItemIdentification and Characterisation of Pseudomonas 16S Ribosomal DNA from Ileal Biopsies of Children with Crohn's Disease(PUBLIC LIBRARY SCIENCE, 2008-10-31)Molecular analysis of bacterial 16S rRNA genes has made a significant contribution to the identification and characterisation of bacterial flora in the human gut. In particular, this methodology has helped characterise bacterial families implicated in the aetiology of inflammatory bowel disease (IBD). In this study we have used a genus specific bacterial 16S PCR to investigate the prevalence and diversity of Pseudomonas species derived from the ileum of children with Crohn's disease (CD), and from control children with non-inflammatory bowel disease (non-IBD) undergoing their initial endoscopic examination. Fifty eight percent of CD patients (18/32) were positive using the Pseudomonas PCR, while significantly fewer children in the non-IBD group, 33% (12/36), were PCR positive for Pseudomonas (p<0.05, Fischer's exact test). Pseudomonas specific 16S PCR products from 13 CD and 12 non-IBD children were cloned and sequenced. Five hundred and eighty one sequences were generated and used for the comparative analysis of Pseudomonas diversity between CD and non-IBD patients. Pseudomonas species were less diverse in CD patients compared with non-IBD patients. In particular P.aeruginosa was only identified in non-IBD patients.
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ItemThe burden of hospitalised rotavirus infections in Fiji(ELSEVIER SCI LTD, 2009-11-20)Rotavirus is the most common cause of acute severe dehydrating diarrhoea in young children worldwide. We describe the burden of rotavirus disease and the rotavirus types causing it in the largest city in Fiji. During 2006 and 2007, 592 children under 5 years of age were admitted to hospital in Suva, Fiji with acute diarrhoea. Of the 454 children for whom a stool specimen was tested, 39% were positive for rotavirus and the predominant strain found was the serotype G3[P8]. There is a significant burden of disease due to rotavirus in Fiji and the introduction of rotavirus vaccines into the national immunization schedule may drastically reduce inpatient diarrhoeal disease.