Specific cross-immunity between Hymenolepis nana and H. diminuta: immunization with heterologous and homologous light infections

Abstract

ABSTRACTThe consequences of previous and concurrent infection with two related species of cestodes, Hymenolepis nana and H. diminuta, were studied in CD1 mice. A H. diminuta infection strongly affected the establishment and the survival of a secondary H. nana egg or cyst infection administered 30 days later. An infection of 20 H. nana eggs strongly protected against a 5-cyst H. diminuta challenge, whereas an infection of 10 H. nana cysts was ineffective; 20 H. nana eggs also protected against a challenge with 5 cysts of H. diminuta administered 5 days later. No effects were observed in either parasite during a concurrent infection established by administration of cysts. An H. nana egg-infection was unable to affect the establishment of a secondary H. nana cyst-infection given 1 month later; however a significant decrease in growth was found. Similar results were found when a primary H. nana egg-infection was followed 5 days later by the homologous cyst-infection. But an infection with 5 H. nana cysts was unable to protect against a homologous challenge of 5 cysts or 20 eggs. The reciprocal cross immunity between the heterologous parasites and the failure of protection of homologous challenges are discussed in relation to light infections.