Immunological memory in mice to adult Hymenolepis diminuta (Cestoda)

Following a primary infection with Hymenolepsis diminuta mice were found to be strongly resistant to a challenge infection over a period of eight months. Challenge was by three cysticercoids administered orally, or by inserting into the duodenum one 7-day-old strobilate worm recovered from a donor mouse. Autopsy of immunized mice 6, 8, and 9 days after challenge showed that challenge worms established but that, with few exceptions, only shunted or destrobilated worms remained. Autopsy of recently immunized mice, at daily intervals following challenge, confirmed that transplanted worms establish as well in immunized as in naive mice, and showed that worms grow normally for the first 48 hr but between 48 to 120 hr most worms destrobilate or are lost. In naive mice, transplanted worms survive and grow, approximately doubling their weight daily for at least 6 days (144 hr). The results provide insight to the problem of developing a useful vaccine and the location of memory cells.