Title: Evaluation of Lethal and Non-lethal Sampling for the Detection of WSIV Infection in White Sturgeon (Acipenser transmontanus)
Student: John D. Drennan
Department: Fish & Wildlife Resources and the Aquaculture Research Institute
The most common diagnostic approach for identifying white sturgeon iridovirus (WSIV) infection in white sturgeon involves lethal sampling to obtain tissue sections from the head for histological examination. In the present study, non-lethal sampling of fin tissue by histology and PCR was compared to the lethal sampling method for the ability to detect viral infection in sturgeon undergoing an experimental 80-day co-habitation challenge with WSIV isolated from the Columbia River as well as in asymptomatic sturgeon from the Kootenai River. Lethal and non-lethal sampling of each fish involved sagittally cut half heads and left pectoral fin-punch tissue to obtain stained sections for histological examination as well as the removal of a portion of the right pectoral fin for PCR testing. An increase in mortality started to occur after 40 days in the cohabitation groups and by 80 days reached 94%. All three sampling methods were equally capable of identifying infection following 28 days post challenge. However, non-lethal fin histology did not identify infection earlier than this time point and non-lethal PCR of fin tissue was more likely to detect infection compared to the standard lethal sampling method. Both lethal and non-lethal histology identified the same asymptomatic individuals from the Kootenai River population but no fish were positive by PCR, suggesting genomic differences exist between isolates. Results from this study suggest that WSIV infection requires at least 4 weeks of incubation before it can be identified histologically in fin tissue. Results also suggest that combining PCR and histological examination of fin tissue by non-lethal sampling could provide an alternative approach for detecting infected individuals in small populations where lethal sampling would be detrimental.
For more information, email the PI: Dr. Kenneth Cain”>