Susceptibility of Snails to Infection with Schistosomes is influenced by Temperature and Expression of Heat Shock Proteins.
The freshwater snail,Biomphalaria glabratais the obligate intermediate host for the transmission of the parasitic trematode,Schistosoma mansonithe causative agent of the chronic debilitating neglected tropical disease, schistosomiasis. We showed previously that in juvenile snails, early and significant induction of stress manifested by the expression of stress proteins, Hsp 70, Hsp 90 and reverse transcriptase (RT) of the non- LTR retrotransposon, nimbus, is a characteristic feature of juvenile susceptible NMRI but not resistant BS-90 snails. These latter, however, could be rendered susceptible after mild heat shock at 32°C, revealing that resistance in the BS-90 resistant snail to schistosomes is a temperature dependent trait. Here we tested the hypothesis that maintenance of BS-90 resistant snails at the permissive temperature for several generations affects the resistance phenotype displayed at the non-permissive temperature of 25°C. The progeny of BS-90 snails bred and maintained through several generations (F1 to F4) at 32°C were susceptible to the schistosome infection when returned to room temperature, shedding cercariae at four weeks post-infection. Moreover, the study of expression levels of the heat shock protein (Hsp) 70 protein by ELISA and western blot analysis, showed that this protein is also differentially expressed between susceptible and resistant snails, with susceptible snails expressing more protein than their resistant counterparts after early exposure to wild-type but not to radiation-attenuated miracidia. These data suggested that in the face of global warming, the ability to sustain a reduction in schistosomiasis by using refractory snails as a strategy to block transmission of the disease might prove challenging since non-lethal elevation in temperature, affects snail susceptibility toS. mansoni.
University of the District of Columbia, 4200 Connecticut Ave, Washington, D.C. 20008, USA ; George Washington University, Department of Microbiology, School of Medicine and Health Sciences, 2300 Eye Street NW, Washington, D.C, USA.
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M
Knight
University of the District of Columbia, 4200 Connecticut Ave, Washington, D.C. 20008, USA.
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O
Elhelu
University of the District of Columbia, 4200 Connecticut Ave, Washington, D.C. 20008, USA.
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M
Smith
University of the District of Columbia, 4200 Connecticut Ave, Washington, D.C. 20008, USA.
B
B
Haugen
Schistosomiasis Resource Center, Biomedical Research Institute, 12111 Parklawn Drive, Rockville, USA.
A
A
Miller
Schistosomiasis Resource Center, Biomedical Research Institute, 12111 Parklawn Drive, Rockville, USA.
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N
Raghavan
University of the District of Columbia, 4200 Connecticut Ave, Washington, D.C. 20008, USA.
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C
Wellman
University of the District of Columbia, 4200 Connecticut Ave, Washington, D.C. 20008, USA.
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C
Cousin
University of the District of Columbia, 4200 Connecticut Ave, Washington, D.C. 20008, USA.
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F
Dixon
George Washington University, Department of Microbiology, School of Medicine and Health Sciences, 2300 Eye Street NW, Washington, D.C, USA.
V
V
Mann
George Washington University, Department of Microbiology, School of Medicine and Health Sciences, 2300 Eye Street NW, Washington, D.C, USA.
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G
Rinaldi
Schistosomiasis Resource Center, Biomedical Research Institute, 12111 Parklawn Drive, Rockville, USA.
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W
Ittiprasert
George Washington University, Department of Microbiology, School of Medicine and Health Sciences, 2300 Eye Street NW, Washington, D.C, USA.
P J
PJ
Brindley
Biomphalaria glabrata; Global warming; Resistant BS-90 snails; Schistosoma mansoni; Susceptibility