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Trichinella spiralis: intestinal expression of systemic stage-specific immunity to newborn larvae
Insights
Rats immunized against newborn Trichinella spiralis larvae showed reduced larval migration. This immunity, transferable via serum, specifically targets larval stages, not adult worms.
Area of Science:
- Parasitology
- Immunology
- Helminthology
Background:
- Trichinella spiralis is a parasitic nematode causing trichinellosis.
- Larval migration is a critical stage in the parasite's life cycle and pathogenesis.
- Understanding host immunity against migrating larvae is key to controlling infection.
Purpose of the Study:
- To investigate the efficacy of intravenous immunization with newborn Trichinella spiralis larvae.
- To determine the impact of such immunization on larval migration and establishment.
- To assess the role of antibodies in conferring protection against migrating larvae.
Main Methods:
- Rats were immunized intravenously with newborn T. spiralis larvae.
- Immunized rats were challenged with adult T. spiralis worms or larvae.
- Larval recovery was quantified in thoracic duct lymph, portal vein blood, and peritoneal fluid.
- Passive transfer of immune serum was performed in naive rats.
Main Results:
- Intravenous immunization conferred specific immunity against newborn T. spiralis larvae.
- Larval recovery in thoracic duct lymph and portal vein blood was reduced by 75-90%.
- Larval migration was delayed and inhibited, with no larvae found in peritoneal fluid.
- Adult worm establishment and fecundity were unaffected.
- Immune serum transfer replicated the protective effects on larval migration.
Conclusions:
- Intravenous immunization effectively induces immunity against migrating newborn T. spiralis larvae.
- This immunity primarily impacts larval translocation, not adult worm parameters.
- Antibodies play a significant role in mediating protection against migrating larvae.
- The findings suggest potential strategies for controlling trichinellosis by targeting larval migration.
Abstract:
Rats immunized with newborn Trichinella spiralis larvae i.v. were found to confer a specific anti-newborn larvae immunity in the small intestine. In rats immunized with newborn larvae i.v. and then challenged with adult worms intraintestinally, total newborn larvae recovery was reduced by 75-90% in thoracic duct lymph and in hepatic portal vein blood. No newborn larvae were found in the peritoneal fluid of immunized rats. In addition to an absolute reduction in number, larval migration from the small intestine to the thoracic duct was delayed by 6-12 h and migration to the portal vein was inhibited for at least 8 h. The establishment of adult worms in the small intestine and female worm fecundity were not affected by anti-newborn larvae immunity. Identical quantitative effects on newborn larvae migration from the small intestine were achieved by homologous transfer of anti-newborn larvae immune serum i.v. into naive recipient rats.