Rate of Clearance of Vibrio fetus var. venerealis in the Rabbit.

The rate of clearance of Vibrio fetus var. venerealis was measured by using in vivo and in vitro methods. The rate of clearance from the circulating blood increased in immune rabbits and reached a plateau 4 days after immunization. Thereafter in vivo clearance did not increase further despite rising agglutinin titers. Vibriocidal activity of freshly drawn blood paralleled the rate of in vivo clearance although it was less effective at 4 days. Vibriocidal activity of immune serum was not demonstrated at the same intervals of time as the freshly drawn blood. Vibriocidal activity of immune sera plus complement was demonstrated after 1 hr of incubation at 37 C in a candle jar. An effective systemic immune response to V. fetus var. venerealis can be elicited in the rabbit. These results suggest that humoral antibodies play an important role in effecting acquired immunity against V. fetus var. venerealis.