| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1990: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1989: ¥900,000 (Direct Cost: ¥900,000)
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| Research Abstract |
Strongyloides venezuelensis is a rodent parasite which is infective to mice. In the present study, the murine infection model with S. venezuelensis was found to be a more useful model for the study of human strongyloidiasis than that with S. ratti, because S. venezuelensis is much more infective to mice and also because the migratory route in mice may be comparable to that of S. stercoralis in humans. The mice infected with S. venezuelensis were also found to aquire an almost complete resistance to the secondary infection after expulsion of intestinal adults of the primary infection.
Unlike the immunocompetent nu/+ mice, the hypothymic nude (nu/nu) mice were unable to expel the adult worms and no aquired resistance to rechallenge was observed among them. The expulsion of adult worm, as well as the resistance against migratory larvae in the secondary infection, were transferrable to nude mice by spleen cells from intact nu/+ mice, but not by infected serum. These results support the hypothesis that direct worm immunity and worm expulsion are a T cell-dependent phenomenon.
In another experiment in which inetrleukin-5 (IL-5) was depleted by treatment with anti-IL-5 monoclonal antibodies, the anti-IL-5 treatment did not affect worm burden and faecal egg output after primary infection. However, when mice were treated after expulsion of intestinal adults, the worm recovery from lungs after the secondary infection was the same as that in the primary infection. The results suggested that the host's protective immunity against tissuemigrating larvae was IL-5-dependent but intestinal immunity was not.
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