The capacity of extracts or excretory-secretory products of adult and larval stages of Ascaris suum to induce protective immunity was evaluated. Extracts of 2nd, 3rd or 4th-stage larvae were unable to induce significant protection while adult worms did so. The excretory-secretory products of the adult or larval stages did not induce protection to a challenge infection. However, larvae cultured from the 3rd to the 4th stage produced a substance which was capable of inducing a significant level of protection. It is postulated that this immunogen is associated with the metabolism of the larvae and is involved with the developmental and moulting processes.
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Acknowiedgements-The authors wish to express their appreciationt o Mr. DerekM uncey,M rs. RosettaG oss and Miss Norma Molina for their assistancet hroughout these studies. This work was supported in part by U.S.P.H.S.R esearchG rant AI-06262R, esearcThr aining Grant AI-00302a nd BiomediaSl cienceSs upportG rant RRO-7083.
- Ascaris suum
- excretory-secretory products
- guinea pig
- soluble antigens