title: Microassay for interferon, using [3H]uridine, microculture plates, and a multiple automated sample harvester.
abstract: A microassay for interferon is described which uses target cells grown in microculture wells, [3H]uridine to measure vesicular stomatitis virus replication in target cells, and a multiple automated sample harvester to collect the radioactively labeled viral ribonucleic acid onto glass fiber filter disks. The disks were placed in minivials, and radioactivity was counted in a liquid scintillation spectrophotometer. Interferon activity was calculated as the reciprocal of the highest titer which inhibited the incorporation of [3H]uridine into viral ribonucleic acid by 50%. Interferon titers determined by the microassay were similar to the plaque reduction assay when 100 plaque-forming units of challenge vesicular stomatitis virus was used. However, it was found that the interferon titers decreased approximately 2-fold for each 10-fold increase in the concentration of challenge vesicular stomatitis virus when tested in the range of 10(2) to 10(5) plaque-forming units. Interferon titers determined by the microassay show a high degree of repeatability, and the assay can be used to measure small and large numbers of interferon samples.
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods*; D002460:Cell Line; D007372:Interferons / Q000032:analysis* / Q000494:pharmacology; D051379:Mice; D012367:RNA, Viral / Q000096:biosynthesis; D014529:Uridine / Q000378:metabolism; D014721:Vesicular stomatitis Indiana virus / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D010948:Viral Plaque Assay
chemical_list: D012367:RNA, Viral; D007372:Interferons; D014529:Uridine