Determination of the duration of a primary immune response and the ID50 of ALA rabbit rotavirus in rabbits

Abstract

The rabbit model of rotavirus infection has been used to examine the immune response to rotavirus infection and to evaluate strategies for rotavirus vaccine development. To determine the 50% infectious does (ID50) of tissue culture adapted ALA virus, rabbits were orally inoculated with 101-103 PFU of ALA rotavirus. The ID50 of ALA virus was determined to be 1.7x102 PFU. The immune response induced in rabbits infected at low virus doses (102-103 PFU) was of similar magnitude to the immune responses induced with a high dose (106 PFU) inoculum, indicating that the immune response to ALA rotavirus in rabbits is not dose dependent. To determine if a single rotavirus inoculation would induce a long lasting immune response, four rabbits were inoculated once with ALA virus (3.5 x 105 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 titers 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.