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Resistance to reinfection with Schistosoma japonicum in the mouse
Abstract:
BALB/c and outbred mice infected with a Philippine isolate of Schistosoma japonicum for 50 to 60 days expressed strong resistance to reinfection. The extent of this reinfection resistance ranged from 72 to 93% in 5 experiments (mean = 80% resistance) as determined by numbers of immature worms recovered from already infected and age- and sex-matched challenge control mice exposed 20 days previously to cercariae. Determination of numbers of recoverable worms from (the initial) infection suggest that adult worms are lost progressively during the period in which impressive resistance to reinfection is demonstrable. An important unresolved question is whether loss of adult worms is related in any way to expression of resistance to reinfection. Some indirect evidence indicates that the major component of reinfection resistance is expressed prior to day 4 of challenge infection. This evidence derives from analysis of lung petechiae which, in a primary infection, have been shown to provide an indication of number of adult worms which can be detected subsequently (e.g. at 30-40 days of infection). Although anti-parasite immune response have not yet been shown to be responsible for this apparent concomitant immunity, the magnitude of resistance to reinfection in the S. japonicum/mouse system should facilitate identification of any immunological effector mechanisms involved.
Insights
Mice infected with Schistosoma japonicum develop strong resistance to reinfection, losing adult worms as immunity develops. This resistance may be linked to early immune responses against the parasite.
Area of Science:
- Immunology
- Parasitology
- Infectious Diseases
Background:
- Schistosomiasis japonica is a significant human parasitic disease.
- Understanding host resistance mechanisms is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the development of resistance to reinfection in mice infected with Schistosoma japonicum.
- To explore the relationship between adult worm burden and resistance to superinfection.
Main Methods:
- BALB/c and outbred mice were infected with Schistosoma japonicum.
- Reinfection resistance was assessed by comparing worm burdens in previously infected and control mice.
- Lung petechiae were analyzed as an indicator of adult worm burden.
Main Results:
- Mice exhibited 72-93% resistance to reinfection.
- Adult worm loss occurred progressively during the development of resistance.
- Evidence suggests major resistance is expressed before day 4 of challenge infection.
Conclusions:
- The Schistosoma japonicum/mouse model demonstrates significant concomitant immunity.
- Further research is needed to identify the immunological mechanisms underlying this resistance.
- Understanding these mechanisms could lead to novel therapeutic strategies for schistosomiasis.