DETERMINATION OF THE DURATION OF A PRIMARY IMMUNE-RESPONSE AND THE ID50 OF ALA RABBIT ROTAVIRUS IN RABBITS

The rabbit model of rotavirus infection has been used to examine the i mmune response to rotavirus infection and to evaluate strategies for r otavirus vaccine development. To determine the 50% infectious does (ID 50) of tissue culture adapted ALA virus, rabbits were orally inoculate d with 10(1)-10(3) PFU of ALA rotavirus. The ID50 Of ALA virus was det ermined to be 1.7 x 10(2) PFU. The immune response induced in rabbits infected at low virus doses (10(2)-10(3) PFU) was of similar magnitude to the immune responses induced with a high dose (10(6) PFU) inoculum , indicating that the immune response to ALA rotavinus in rabbits is n ot dose dependent. To determine if a single rotavirus inoculation woul d induce a long lasting immune response, four rabbits were inoculated once with ALA virus (3.5 x 10(5) PFU) and their serologic and mucosal antirotavirus titers were monitored at intervals for 1.5-2 years. The infected rabbits maintained serologic and mucosal rotavirus antibody t iters until the final time point more than 700 days post inoculation. These data are important because they indicate that the antigenic load achieved following a single oral inoculation is sufficient to achieve long lasting immunity, the goal of any potential vaccine.