Azza H. Mohamed

Sublethal toxicity of Roundup to immunological and molecular aspects of Biomphalaria alexandrina to Schistosoma mansoni infection.

The present study was performed to elucidate the cellular mechanisms of Biomphalaria alexandrina snails hemocytes against sublethal concentration (10 mg/L) of herbicide Roundup (48% Glyphosate) and/or Schistosoma mansoni infection during 7 days of exposure. Obtained results indicated that herbicide treatment and/or infection led to significant increase (P<0.05) in total hemocytes count during exposure period. Examination of hemocytes monolayers resulted in observation of 3 morphologically different cell types, round small, hyalinocytes and spreading hemocytes. Spreading hemocytes are the dominant, more responsive and highly phagocytic cell type in all experimental groups. Moreover, the exposure to herbicide, infection or both together led to a significant increase (P<0.05) of in vitro phagocytic activity against yeast cells during 7 days of exposure. In addition, flow cytometric analysis of cell cycle and comet assay, resulted in DNA damage in B. alexandrina hemocytes exposed to herbicide and/or S. mansoni infection when compared to control group. The immunological responses as well as molecular aspects in B. alexandrina snails have been proposed as biomarkers of exposure to environmental pollutants.

The relationship between genetic variability and the susceptibility of Biomphalaria alexandrina snails to Schistosoma mansoni infection

In the present study, Biomphalaria snails collected from five Egyptian governorates (Giza, Fayoum, Kafr El-Sheikh, Ismailia and Damietta), as well as reference control Biomphalaria alexandrina snails from the Schistosome Biological Supply Center (SBSC) (Theodor Bilharz Research Institute, Egypt), were subjected to species-specific polymerase chain reaction (PCR) assays to identify the collected species. All of the collected snails were found to be B. alexandrina and there was no evidence of the presence of Biomphalaria glabrata. Randomly amplified polymorphic DNA (RAPD)-PCR assays showed different fingerprints with varying numbers of bands for the first generation (F₁) of B. alexandrina snail populations (SBSC, Giza, Fayoum, Kafr El-Sheikh, Ismailia and Damietta). The primer OPA-1 produced the highest level of polymorphism and amplified the greatest number of specific bands. The estimated similarity coefficients among the B. alexandrina populations based on the RAPD-PCR profiles ranged from 0.56 (between SBSC and Ismailia snails) to 0.72 (between Ismailia and Kafr El-Sheikh snails). Experimental infection of the F₁ of progeny from the collected snails with Schistosoma mansoni (SBSC strain) showed variable susceptibility rates ranging from 15% in the Fayoum snail group to 50.3% in SBSC snails. A negative correlation was observed between the infection rates in the different snail groups and the distances separating their corresponding governorates from the parasite source. The infection rates of the snail groups and their similarity coefficients with SBSC B. alexandrina snails were positively correlated. The variations in the rates of infection of different B. alexandrina groups with S. mansoni, as well as the differences in the similarity coefficients among these snails, are dependent not only on the geographical distribution of the snails and the parasite, but also on the genetic variability of the snails. Introduction of this variability into endemic areas may reduce the ability of the parasite to infect local hosts and consequently reduce schistosomiasis epidemiology.

Histamine Immunoreactive Elements in the Central and Peripheral Nervous Systems of the Snail, Biomphalaria spp., Intermediate Host for Schistosoma mansoni

Histamine appears to be an important transmitter throughout the Animal Kingdom. Gastropods, in particular, have been used in numerous studies establishing potential roles for this biogenic amine in the nervous system and showing its involvement in the generation of diverse behaviours. And yet, the distribution of histamine has only previously been described in a small number of molluscan species. The present study examined the localization of histamine-like immunoreactivity in the central and peripheral nervous systems of pulmonate snails of the genus Biomphalaria. This investigation demonstrates immunoreactive cells throughout the buccal, cerebral, pedal, left parietal and visceral ganglia, indicative of diverse regulatory functions in Biomphalaria. Immunoreactivity was also present in statocyst hair cells, supporting a role for histamine in graviception. In the periphery, dense innervation by immunoreactive fibers was observed in the anterior foot, perioral zone, and other regions of the body wall. This study thus shows that histamine is an abundant transmitter in these snails and its distribution suggest involvement in numerous neural circuits. In addition to providing novel subjects for comparative studies of histaminegic neurons in gastropods, Biomphalaria is also the major intermediate host for the digenetic trematode parasite, which causes human schistosomiasis. The study therefore provides a foundation for understanding potential roles for histamine in interactions between the snail hosts and their trematode parasites.

The hepatoprotective activity of blue green algae in Schistosoma mansoni infected mice.

This study aims to evaluate the immunomodulatory effects of a natural product, blue green algae (BGA) (100 mg/kg BW), alone or combined with praziquantel PZQ (250 mg/kg BW) on granulomatous inflammation, liver histopathology, some biochemical and immunological parameters in mice infected with Schistosoma mansoni. Results showed that the diameter and number of egg granuloma were significantly reduced after treatment of S. mansoni-infected mice with BGA, PZQ and their combination. The histopathological alterations observed in the liver of S. mansoni-infected mice were remarkably inhibited after BGA treatments. BGA decreased the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) as well as the level of total protein (TP) while the level of albumin was increased. Treatment of infected mice with BGA, PZQ as well as their combination led to significant elevation in the activities of hepatic antioxidant enzymes glutathione peroxidase (GPX) and glutathione-S-transferase (GST) as compared with control group. Combination of BGA and PZQ resulted in significant reduction in the level of intercellular adhesion molecules-1 (ICAM-1), vascular adhesion molecules-1 (VCAM-1) and tumor necrosis factor-alpha (TNF-α) when compared to those of the S. mansoni-infected group. Overall, BGA significantly inhibited the liver damage accompanied with schistosomiasis, exhibited a potent antioxidant and immunoprotective activities. This study suggests that BGA can be considered as promising for development a complementary and/or alternative medicine against schistosomiasis.

Molecular and serological prevalence of Toxoplasma gondii in pregnant women and sheep in Egypt

OBJECTIVE To investigate molecular and serological prevalence of Toxoplasma gondii (T. gondii) in pregnant women and sheep in Egypt. METHODS Blood samples collected from healthy 364 pregnant women and 170 sheep were investigated for T. gondii antibodies and parasitemia using highly specific and sensitive surface antigen (TgSAG2) based enzyme linked immunosorbent assay (ELISA) and real time-polymerase chain reaction (RT-PCR). RESULTS Overall prevalence of T. gondii was 51.76%, 17.65% in sheep, 33.79%, 11.81% in pregnant women, using ELISA and RT-PCR respectively. Significant differences in T. gondii prevalence were observed on the basis of contact with cats or soil in pregnant women using either RT-PCR or ELISA. In pregnant women, a significant increase was detected in aged and those eating under-cooked mutton using simultaneous ELISA/RT-PCR. CONCLUSIONS Consumption of under-cooked infected mutton is an important source of human infection and the combination of the two assays provide accurate and precise data during infection.

Tissue Responses Exhibited by Biomphalaria Alexandrina Snails from Different Egyptian Localities Following Exposure to Schistosoma Mansoni Miracidia

Snails’ susceptibilities to infection with Schistosoma mansoni were determined through observation of infection rates, total cercarial production and tissue responses of the first generation (F 1 ) of Biomphalaria alexandrina snails originally collected from different Egyptian governorates (Giza, Fayoum, Kafr El-Sheikh, Ismailia and Damietta). B. alexandrina snails from Schistosome Biological Supply Center (SBSC, TBRI), Giza, Egypt were used as a reference control group. S. mansoni miracidia from SBSC were used for snail infection. Snails’ responses towards penetrating S. mansoni miracidia were compared between groups. The emergence of cercariae for a three-month period and the calculation of survival and infection rates, in control (Schistosome Biological Supply Center-SBSC) and infected snails were evaluated. The results indicated SBSC and Giza snails showed a greater susceptibility to infection and lower mortality rates. In addition, at 6 and 72 hrs post-exposure to miracidia all the snail groups showed no difference in the anatomical locations of sporocysts. The larvae were found in the head-foot, the mantle collar and the tentacles of the snails. Sporocysts showed normal development with low tissue reactions in SBSC and Giza snail groups infected with S. mansoni miracidia (Giza origin). However, in Fayoum, Kafr El-Sheikh, Ismailia and Damietta snail groups, variable tissue responses were observed in which numerous hemocytes made direct contact with S. mansoni larvae forming capsules. The results suggested that, different responses of B. alexandrina snail’s hemocytes towards S. mansoni are related to the degree of susceptibility of these snails. So this is important in planning the strategy of schistosomiasis control.

Influence of Solar Energy on Encysted Parasitic Protozoa Giardia and Entamoeba spp in Water-Treatment Plants, Egypt

Polluted water with parasitic protozoa (Giardia lamblia and Entamoeba histolytica) causes many serious health problems like diarrhea and gastrointestinal diseases. The present study investigated the applicability of solar energy for disinfection of parasitic protozoa in polluted water. One-side blackened bottles of two liters volume each were continuously exposed to direct sun light for about seven hours which maintained water temperature in the range of 50-60 °C that was enough for destroying most of the encysted parasitic protozoa. Complete destruction of the encysted protozoa was achieved in both bottles facing south and those vertically in position at 60 °C with an ambient temperature of 40 °C. The influence of water temperature against the viability of these two cysts was found to be highly significant (P < 0.001) in both cases particularly those of Giardia where its regression coefficient equal -1.5 as compared to that of Entamoeba (-1.27). The low cost and operational simplicity of this study make it affordable and usable. It is more useful in rural areas where other sources of energy like electricity and gas are not easily available.

Immunization efficacy of ozone-exposed cercariae against subsequent Schistosoma mansoni challenge infection

CD1 mice were immunized subcutaneously with 20 ozone-exposed (70μg/ml, 1 minute exposure) Schistosoma mansoni cercariae weekly/three weeks. The efficacy of immunization was assessed 10 weeks post challenge infection by the determination of the worm burden, ova count, oogram, granuloma diameter, IgG reactions against soluble egg antigen (SEA) and tegument structural changes of recovered worms that are immunized. A reduced worm length and a reduction in worm burden were observed in the immunized group as compared to the infected not immunized group. Moreover, no ova were found in liver and intestine from the immunized mice as compared with infected control mice. Also, immunization with ozonated cercariae showed a decrement in the mean relative weight of liver and spleen. Total leukocyte count was increased in the immunized animal as compared to the infected control. The level of total IgG antibody against SEA decreased in immunized mice as compared with the infected control mice. Scanning electron microscope (SEM) images of worms recovered 10 weeks post challenge from the immunized group revealed extensive tegumental destruction. This study underlines the significant role of ozone attenuated cercariae vaccine against S. mansoni infection, which generated specific immunity with a significant level of protection.