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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 110, No. 5, 2015, pp. 585-595
Bioline Code: oc15079
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 110, No. 5, 2015, pp. 585-595

 en Impact of the age of Biomphalaria alexandrina check for this species in other resources snails on Schistosoma mansoni check for this species in other resources transmission: modulation of the genetic outcome and the internal defence system of the snail
Abou-El-Naga, Iman Fathy; Sadaka, Hayam Abd El-Monem; Amer, Eglal Ibrahim; Diab, Iman Hassan & Khedr, Safaa Ibrahim Abd El-Halim


Of the approximately 34 identified Biomphalaria species, Biomphalaria alexandrina check for this species in other resources represents the intermediate host of Schistosoma mansoni check for this species in other resources in Egypt. Using parasitological and SOD1 enzyme assay, this study aimed to elucidate the impact of the age of B. alexandrina snails on their genetic variability and internal defence against S. mansoni infection. Susceptible and resistant snails were reared individually for self-reproduction; four subgroups of their progeny were used in experiment. The young susceptible subgroup showed the highest infection rate, the shortest pre-patent period, the highest total cercarial production, the highest mortality rate and the lowest SOD1 activity. Among the young and adult susceptible subgroups, 8% and 26% were found to be resistant, indicating the inheritance of resistance alleles from parents. The adult resistant subgroup, however, contained only resistant snails and showed the highest enzyme activity. The complex interaction between snail age, genetic background and internal defence resulted in great variability in compatibility patterns, with the highest significant difference between young susceptible and adult resistant snails. The results demonstrate that resistance alleles function to a greater degree in adults, with higher SOD1 activity and provide potential implications for Biomphalaria control. The identification of the most susceptible snail age enables determination of the best timing for applying molluscicides. Moreover, adult resistant snails could be beneficial in biological snail control.

Biomphalaria alexandrina; Schistosoma mansoni; age; genetics; internal defence system

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