Serum interferon in bovine ephemeral fever

Ephemeral fever was produced experimentally in eight cows. Clinical signs wereapparent 80 to 130 h after inoculation and blood samples were subsequentlycollected at hourly intervals. Recovery followed 34 to 82 h after the onset offever. Neutralising antibodies were first detected in serum 72 to 96 h afterrecovery. Plasma fibrinogen levels rose from a mean of 59 ::t 21 mg/l-1 to a peakof 153+ 44 mg/l-1, 56 to 96 h after the initial rectal temperature rise. Interferonwas detected in serum approximately 8 -14 h before the temperature andneutrophils began to rise and reached a peak 10 h later. The level of interferonfell before clinical recovery. Increased levels of interferon were detected inseven natural cases of ephemeral fever.