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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 90, No. 4, 1995, pp. 507-509
Bioline Code: oc95099
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 90, No. 4, 1995, pp. 507-509

 en Schistosoma mansoni: reinfections and concomitant immunity in mice. Importance of perfusion time after challenge infection for evaluation of immunoprotection
Paulo Marcos Z Coelho; Romulo T Mello & Teresinha Ev Pollom


The concomitant immunity in the presence of repeated infections (with 15 cercariae) was studied in mice sacrificed on the 20th day after each infection. The comparison of the averages of immature worms, recovered from mice submitted to reinfection, with those of their respective controls (previously uninfected) showed a significantly lower worm recovery rate in the animals with previous infections (concomitant immunity). However, statistically significant differences could not be detected among the various groups of animals, when the mice that accumulated worms in this mature stage were perfused.

The theoretical projection based on the accumulation of young worms which developed to adult ones indicates a lower recovery rate of adult worms in the animals with concomitant immunity, but this projection was not corroborated by the experimental data. The visceral hemodynamic alterations that occurred in reinfections due to the pathogeny, favouring recirculation of the recent arriving worms to the portal system, could explain the lower recovery rate of immature worms, which could remain in other organs on the occasion of perfusion of the portal system.

These results suggest that special care should be taken when one wants to investigate concomitant immunity in mice based on the distinction of the immature worms from challenge infection and the mature ones from primary infection.

Schistosoma mansoni - concomitant immunity - perfusion time - immunoprotection

© Copyright 1995 Fundacao Oswaldo Cruz
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