Circulating interferon-alpha in patients with Kyasanur forest disease.

Endogenous interferon (IFN) levels were monitored in acute (51) and convalescent phase (19) sera collected from patients suffering from Kyasanur forest disease (KFD). Levels of circulating IFN in the acute samples (GM 216.3 +/- 8.7) collected between 4 to 7 post onset day (POD) were significantly higher (P less than 0.001) than the convalescent samples (GM 13.19 +/- 1.6) collected between 30th to 90th POD. Interferonemia was concomitant with the viraemic phase. Neutralization studies indicated that the endogenous (circulating) IFN was antigenically similar to acid stable form of IFN-alpha.