Stability of ELISA activity in frozen samples of barley yellow dwarf virus-infected leaf and leaf extracts
1990
Nazare Pereira, A.M. | Lister, R.M. (Purdue University, West Lafayette, IN (USA))
When replicate samples of barley yellow dwarf virus-infected intact oat (Avena sativa L.) leaf, leaf extracts in phosphate buffer, or chloroform-clarified leaf extracts, were stored frozen at -20 deg C, -80 deg C, or in liquid nitrogen, their enzyme-linked immunosorbent assay (ELISA) activities fluctuated over time and according to the virus isolate involved. With the Purdue (P)-PAV isolate, no significant decrease of ELISA activity was noted with leaf, crude leaf extracts, or clarified extracts stored for up to 4 weeks at -20 deg C, -80 deg C, or in liquid nitrogen, except that clarified extracts stored at -20 deg C deteriorated after 1 week. When tested after 8 weeks, however, ELISA activity was reduced to values that remained similar thereafter for up to 14 weeks, the longest period of storage tested. With the MAV and RPV isolates, significant deterioration in ELISA activity was noted in most samples after 4 weeks of storage, after which ELISA activity appeared to stabilize, although in some cases an increase in activity was observed in samples stored for longer periods. Again, deterioration was most evident after storage of clarified extracts at -20 deg C, which was overall the least effective treatment for preserving ELISA activity.
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