Antiprotozoal potential of Salvadora persica against three virulent subtypes of Blastocystis sp.

Blastocystis sp. is a group of anaerobic protozoa parasitizing the gastrointestinal tract of humans and a broad variety of animals. Evidences of Blastocystis parasites resistance development to antiprotozoal drugs urge the exploration of new therapeutics. Antiprotozoal potential of Salvadora persica, a medicinal plant traditionally used for oral hygiene, was evaluated in vitro against Blastocystis sp. human isolates. Until now, no study has described the effect of S. persica extracts on this parasitic protozoa. Blastocystis sp. positive stool samples collected from patients with gastrointestinal complaints and asymptomatic individuals diagnosed by microscopy were furthermore cultured in vitro and characterized by PCR and multiplex-PCR using sequence-tagged-site primers to determine their subtypes. Out of 21 Blastocystis sp. isolates, five were determined as ST1, 14 as ST3, and two as ST5 subtypes. Antiprotozoal activity of untreated and heat-treated S. persica roots aqueous extracts was evaluated in vitro by serial dilutions on three Blastocystis sp. subtypes; ST1, ST3, and ST5 isolated from symptomatic patients. A significant killing activity was observed with both, untreated and heat-treated aqueous extracts of S. persica at minimal concentration of 2.5 µl/ml compared to parasites' growth controls (P < 0.05). Maximal antiprotozoal effect was reached at a concentration of 20 µl/ml of S. persica aqueous extract. Means of growth inhibition effect obtained with untreated and heat-treated extracts at 40 µl/ml against the three subtypes of Blastocystis sp. were 80% (SD 2.3) and 82% (SD 1.1), respectively. No significant difference was observed in the inhibitory effect of S. persica extracts between the three Blastocystis sp. subtypes. Aqueous extract of S. persica roots contains therefore heat-stable components with significant antiprotozoal activity against Blastocystis sp. subtypes ST1, ST3, and ST5 in vitro. Further investigations are required to determine and characterize the active antiprotozoal components of S. persica roots and their evaluation in vivo.

Subtyping of Blastocystis sp. isolated from symptomatic and asymptomatic individuals in Makkah, Saudi Arabia.

BACKGROUND: Blastocystis is a group of cosmopolitan gastrointestinal parasite of humans and a wide variety of animals. These anaerobic protozoans include more than 17 specific small-subunit ribosomal RNA subtypes, of which nine are found in humans with a variable geographical distribution. Until now, no study has described the Blastocystis subtypes present in Saudi Arabia. METHODS: In total, 1,262 faecal samples were collected from patients with gastrointestinal complaints and asymptomatic individuals visiting two major hospitals. All samples were analysed by F1/R1 diagnostic PCR, microscopy and culture methods. The subtypes of Blastocystis sp. isolates were determined by the sequenced-tagged site (STS)-based method. RESULTS: One-hundred-thirty-three positive cases were detected by F1/R1 diagnostic PCR, of which 122 were also positive by the culture method and 83 by direct microscopy. The sensitivities of direct microscopy and the culture method were 62% and 92%, respectively. Subtype (ST3) was the most prevalent (80.5%), followed by ST1 (14.5%) and ST2 (5%). ST4, ST5, ST6 and ST7 were not detected in this study. ST3 infections were significantly predominant (P < 0.05) among symptomatic patients. CONCLUSIONS: To our knowledge, this study provides the first run-through information on Blastocystis sp. epidemiology in Makkah city, revealing a rather moderate prevalence of 10.5% and the presence of three subtypes, ST1, ST2, and ST3. ST3 was the most predominant, particularly among symptomatic patients.

Vaccination with Toxoplasma lysate antigen and CpG oligodeoxynucleotides: comparison of immune responses in intranasal versus intramuscular administrations.

Toxoplasma gondii (T. gondii) is one of the most successful intracellular protozoan parasites on earth and highly prevalent in most warm-blooded vertebrates. There are no drugs that target the chronic cyst stage of this infection; therefore, development of an effective vaccine would be an important advance in disease control. Oligodeoxynucleotides (ODN) which contain immunostimulatory CG motifs (CpG ODN) can promote T-helper 1 (Th1) responses, an adjuvant activity that is desirable for vaccination against intracellular pathogen. In this study, we compare the immune responses of Toxoplasma susceptible C57BL/6 mice following intranasal and intramuscular vaccination with Toxoplasma lysate antigen (TLA) with or without CpG ODN as adjuvant. Immunized and control non-immunized mice were challenged with 85 cyst of the moderately virulent Beverley strain of T. gondii. Intranasal vaccination gave significantly a higher protection compared to other groups as indicated by prolonged survival and significantly reduced brain cyst burden (P < 0.01). Intranasal vaccination stimulated cellular immunity towards Th1 response characterized by significant INF-γ production (P < 0.01). Furthermore, fecal IgA antibody levels as an indicator of mucosal immune responses were significantly higher (P < 0.05) in intranasal vaccinated group before the challenge compared to all other groups. Intranasal vaccination was not able to upgrade the Th1 humoral arm. In contrast, intramuscular vaccination enhanced humoral immunity towards a type Th1 pattern characterized by a significant increase of specific IgG and Ig2a. Our results suggest that intranasal administration of CpG/TLA would provide a stable, pronounced, and effective vaccine against toxoplasmosis through stimulation of Th1 cellular immunity and mucosal IgA.

Application of adult worm and lung-stage antigens to immunize against Schistosoma mansoni using cytokines as adjuvants.

Different Schistosoma mansoni antigens; adult worm antigen (SWAP) and lung-stage antigen (SLAP) together with different cytokine adjuvants (Interferon-gamma and Interleukin-4) were used to immunize mice against. S. mansoni. Immunization program was directed towards the production of an intense immune response together with balanced T-helper1 and T-helper2 immune responses. The goal of immunization was not only to protect from infection but also to modulate the pathology inflicted by the parasite. Parameters like adult load, egg counts, anti-Schistosoma antibody titers and liver pathology were used to evaluate the different immunization scheme. SLAP antigen has proven to be a better antigen not only in protection but also in pathology modulation. SLAP plus IFN-gamma as an adjuvant was the best immunization regimen with almost 50% protection and a remarkable resolving of parasite pathology. Unexpectedly, IL-4 had a weak but observed adjuvant protective effect. The results is a step in the path for a Schistosoma vaccine that guides the immune system towards a balanced response targeting the pathology induced by the parasite rather than the parasite itself.