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In vitro susceptibility of human Blastocystis subtypes to simeprevir
Shereen F Mossallam1, Salwa A T El-Mansoury1, Mona M Tolba2
1Department of Medical Parasitology, Faculty of Medicine, Alexandria University, Alexandria, Egypt.
Introduction And Aim:
Blastocystis is a common enteric parasite, having a worldwide distribution. Many antimicrobial agents are effective against it, yet side effects and drug resistance have been reported. Thus, ongoing trials are being conducted for exploring anti-Blastocystis alternatives. Proteases are attractive anti-protozoal drug targets, having documented roles in Blastocystis. Serine proteases are present in both hepatitis C virus and Blastocystis. Since drug repositioning is quite trendy, the in vitro efficacy of simeprevir (SMV), an anti-hepatitis serine protease inhibitor, against Blastocystis was investigated in the current study.
Methods:
Stool samples were collected from patients, Alexandria, Egypt. Concentrated stools were screened using direct smears, trichrome, and modified Ziehl-Neelsen stains to exclude parasitic co-infections. Positive stool isolates were cultivated, molecularly subtyped for assessing the efficacy of three SMV doses (100,150, and 200 μg/ml) along 72 hours (h), on the most common subtype, through monitoring parasite growth, viability, re-culture, and also via ultrastructure verification. The most efficient dose and duration were later tested on other subtypes.
Results:
Results revealed that Blastocystis was detected in 54.17% of examined samples. Molecularly, ST3 predominated (62%), followed by ST1 (8.6%) and ST2 (3.4%). Ascending concentrations of SMV progressively inhibited growth, viability, and re-culture of treated Blastocystis, with a non-statistically significant difference when compared to the therapeutic control metronidazole (MTZ). The most efficient dose and duration against ST3 was 150 µg/ml for 72 h. This dose inhibited the growth of ST3, ST1, and ST2 with percentages of 95.19%, 94.83%, and 94.74%, successively and viability with percentages of 98.30%, 98.09%, and 97.96%, successively. This dose abolished Blastocystis upon re-culturing. Ultra-structurally, SMV induced rupture of Blastocystis cell membrane leading to necrotic death, versus the reported apoptotic death caused by MTZ. In conclusion, 150 µg/ml SMV for 72 h proved its efficacy against ST1, ST2, and ST3 Blastocystis, thus sparing the need for pre-treatment molecular subtyping in developing countries.
Insights
Simeprevir (SMV) effectively inhibits Blastocystis growth and viability, offering a promising alternative treatment. This serine protease inhibitor demonstrates potent in vitro efficacy against common Blastocystis subtypes.
Area of Science:
- Medical Parasitology
- Drug Discovery
- Antimicrobial Agents
Background:
- Blastocystis is a prevalent enteric parasite globally.
- Existing treatments for Blastocystis have limitations including side effects and drug resistance.
- Serine proteases are crucial for Blastocystis survival and represent potential therapeutic targets.
Purpose of the Study:
- To investigate the in vitro efficacy of simeprevir (SMV), a serine protease inhibitor, as a potential anti-Blastocystis agent.
- To evaluate SMV's effectiveness against common Blastocystis subtypes (ST1, ST2, ST3).
Main Methods:
- Stool samples were collected and screened for Blastocystis.
- Positive isolates were molecularly subtyped.
- The in vitro efficacy of three SMV doses (100, 150, 200 μg/ml) over 72 hours was assessed by monitoring parasite growth, viability, and re-culture.
- Ultrastructural changes were examined.
Main Results:
- Simeprevir (SMV) demonstrated dose-dependent inhibition of Blastocystis growth and viability.
- A concentration of 150 μg/ml SMV for 72 hours was highly effective, inhibiting growth by over 94% and viability by over 97% for ST1, ST2, and ST3.
- SMV induced necrotic cell death, distinct from the apoptotic cell death caused by metronidazole.
- SMV showed comparable efficacy to metronidazole without statistical significance.
Conclusions:
- 150 μg/ml of simeprevir (SMV) for 72 hours is effective against Blastocystis subtypes ST1, ST2, and ST3 in vitro.
- SMV represents a potential alternative therapeutic agent for Blastocystis infections.
- The findings suggest SMV could be used without the need for pre-treatment molecular subtyping in resource-limited settings.
