Abstract
As described in a precious study, Sendai virus formed plaques in chick embryo (CE) cell monolaycrs with the aid of trypsin incorporated into the agar overlay medium. The virus also tormed plaques in monkey kidney (MK) cell monolaycrs without the aid of trypsin. Sendai virus grown in CE cells, as well as that grown in either of other stable cell lines tested, showed much lower plaque-forming unit (PFU) titers in MK monolayers than in CE mo nolayers. Howeycr, a mild trypsin treamnent of the virus grown in these cells enhanced its PFU titers in MK monolayers to the level obtained in CE monolayers. In spite of this marked infectivity enhancement, the enzyme treatment little affected the hemagglutinin titers of the virus. On the other hand, Sendai virus grown in embryonated eggs or MK cells showed similar PFU titers in both CE and MK monolayers and also showed no evidence of infectivty enhancement due to the enzyme treatment.
