Characterization of orthoreoviruses isolated from American crow (Corvus brachyrhynchos) winter mortality events in eastern Canada
Bibliographic record
Abstract
A putative reovirus has been isolated from mortality events in American crows,\nof eastern Canada. The purpose of this research is to establish biological characteristics\nof this American crow reovirus, its genetic relatedness to other reoviruses and to\ndetermine its pathogenic significance for commercial poultry. The growth properties of\nthe isolates were assessed in VERO and QM 5 cell lines, the partial S2 and S4 genome\nsegments were sequenced and phylogenetic analysis were performed and a\npathogenicity trial in SPF chickens was done.\nTwenty-six suspect orthoreoviruses (2 from PEI and 24 from Ontario) were\nisolated from winter mortality events affecting American crow in eastern Canada.\nFourteen isolates exhibiting CPE were analyzed (2 from PEI and 12 from Ontario)\nusing avian orthoreovirus genome segment-specific primers for segments S2 and S4, in\na conventional one-step RT-PCR assay. Results confirmed that 14 of the 26 viruses\nwere from the family Reoviridae, 100 % of the PEI isolates (2/2) and 91.67% of the\nOntario isolates (11/12) were avian orthoreoviruses; and 1/24 (4.2%) of the Ontario\nisolates was a rotavirus. This is the first report of isolation and accurate identification of\navian orthoreoviruses from American crow mortality events supporting the etiological\nrole of American crow orthoreoviruses in the winter crow mortality syndrome.\nAnalysis of the S2 sequences discovered that the PEI and Ontario isolates had\nsequence similarity to avian orthoreovirus isolates of commercial poultry. Analysis of\nthe S4 sequences revealed that both isolates had the highest sequence similarity with\nTvärminne avian virus (TVAV). S2 and S4 genome segments of the two isolates had\n99.8% and 95.2% sequence similarity respectively with each other. Phylogenetic analysis of S2 sequences placed these viruses in the same cluster\nwith avian orthoreoviruses of commercial poultry. However, the S4 phylogenetics\nestablished that American crow orthoreovirus isolates have a closer relationship to the\nTVAV. These American crow isolates are genetically distinct from most other avianorigin\northoreoviruses and have a reassorted S4 segment which has been acquired from\nthe TVAV.\nIn the experimental infection of SPF chickens, American crow orthoreovirus\nisolates crossed the species barrier resulted in clinical disease with high morbidity and\nlow mortality producing enteric lesions in the lower gastrointestinal tract from\nventriculus to jejunum.\nThe sensitivity and specificity of S4 genome segment specific conventional onestep\nRT-PCR assay for American crow orthoreovirus was assessed. The assay had a\n100% analytical specificity, however virus isolation in VERO cells had higher detection\nlimit than the RT-PCR. Application of this assay for the detection of American crow\northoreovirus in intestinal tissue confirmed 9 positives out of 44 samples tested. In\naddition to the 9 RT-PCR positives, another 5 samples of the 44 produced characteristic\nCPE in VERO cells. Infected first passage VERO cell lysate of these 5 samples yielded\northoreovirus S4 segment specific PCR band confirming the CPE observed in VERO\ncells was due to American crow orthoreovirus. This RT-PCR assay is useful as an\nancillary diagnostic tool for routine detection of avian orthoreoviruses.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".