tailieunhanh - Báo cáo y học: "No influence of oxygen levels on pathogenesis and virus shedding in Salmonid alphavirus (SAV)challenged Atlantic salmon (Salmo salar L.)"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: No influence of oxygen levels on pathogenesis and virus shedding in Salmonid alphavirus (SAV)challenged Atlantic salmon (Salmo salar L.) | Andersen et al. Virology Journal 2010 7 198 http content 7 1 198 VIROLOGY JOURNAL RESEARCH Open Access No influence of oxygen levels on pathogenesis and virus shedding in Salmonid alphavirus SAV -challenged Atlantic salmon Salmo salar L. Linda Andersen1 Kjartan Hodneland2 Are Nylund1 Abstract Background For more than three decades diseases caused by salmonid alphaviruses SAV have become a major problem of increasing economic importance in the European fish-farming industry. However experimental infection trials with SAV result in low or no mortality very different from most field outbreaks of pancreas disease PD . This probably reflects the difficulties in reproducing complex biotic and abiotic field conditions in the laboratory. In this study we looked at the relationship between SAV-infection in salmon and sub-lethal environmental hypoxia as a result of reduced flow-through in tank systems. Results The experiment demonstrated that constant reduced oxygen levels 60-65 oxygen saturation mg L did not significantly increase the severity or the progress of pancreas disease PD . These conclusions are based upon assessments of a semi-quantitative histopathological lesion score system morbidities mortalities and levels of SAV RNA in tissues and water measured by 1 MDS electropositive virus filters and downstream real-time RT-PCR . Furthermore we demonstrate that the fish population shed detectable levels of the virus into the surrounding water during viraemia 4-13 days after . infection and prior to appearance of severe lesions in heart 21-35 dpi . After this period viral RNA from SAV could not be detected in water samples although still present in tissues gills and hearts at lasting low levels. Lesions could be seen in exocrine pancreas at 7-21 days post infection but no muscle lesions were seen. Conclusions In our study experimentally induced hypoxia failed to explain the discrepancy between the severities reported from field outbreaks

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