To elucidate the mechanisms of antischistosoma resistance,
drug-resistant Schistosoma mansoni laboratory isolates are essential.
We developed a new method for inducing resistance to praziquantel (PZQ)
using successive drug treatments of Biomphalaria glabrata snails
infected with S. mansoni. Infected B. glabrata were treated three times
with 100 mg/kg PZQ for five consecutive days with a one-week interval
between them. After the treatment, the cercariae (LE-PZQ) produced from
these snails and the LE strains (susceptible) were used to infect mice.
Forty-five days after infection, mice were treated with 200, 400 or 800
mg/kg PZQ. Thirty days post-treatment, we observed that the mean number
of worms recovered by perfusion was significantly higher in the group
of mice infected with the LE-PZQ isolate treated with 200 and 400 mg/kg
in comparison to the LE strain with the same treatment. Moreover, there
was a significant difference between the ED50 (effective dose required
to kill 50% of the worms) of the LE-PZQ isolate (362 mg/kg) and the LE
strain (68 mg/kg). In the in vitro assays, the worms of the LE-PZQ
isolate were also less susceptible to PZQ. Thus, the use of infected
snails as an experimental model for development of resistance to S.
mansoni is effective, fast, simple and cheap