DIVERSITY AND COMPARATIVE STUDIES ON BULINUS SNAILS COLLECTED FROM TWO LOCALITIES IN EGYPT.

A comparative study of the shell structure, seasonal temperature and Calcium content of Bulinus snails from two areas (Damietta and Giza) in Egypt was done and compared with laboratory snails from Schistosome Biological Supply Center (SBSC). The shells of collected snails identified as Bulinus truncatus, showed a wide variation in shape. The results showed a significant differences were detected between the populations from SBSC and Damietta (p<0.05) for mean of measured shell width, aperture length, length of spire and number of whorls. The populations from Giza and Damietta governorates showed significant differences (P<0.05) in mean of measured length of diagonal, length of body whorl above aperture, length of spire and number of whorls. There were no statically significant differences between the populations from SBSC and Giza. The seasonal temperature affected on susceptibility of snails to infection with Schistosoma haematobium. The. mean prepatent period was short in summer and long in winter. The shells of S. haematobium - infected B. truncatus snails showed hypocalcifiction from all localities.

Osteoclastogenesis and lymph node organogenesis in different species of Egyptian rats.

The development of lymphoid organs depends on the correct expression of several molecules within a defined timeframe during ontogeny. Although this is an extremely complex process, with each secondary lymphoid tissue requiring subtly different signals, a common framework for lymphoid development is beginning to emerge. Bone remodeling is tightly regulated by a molecular trial composed of OPG/RANK/RANKL. The receptor activator of RANKL (localized on osteoblasts) enhances osteoclastogenesis via interaction with its receptor RANK (localized on osteoclasts), whereas osteoprotegerin (OPG) (produced by osteoblasts) inhibits this osteoclastogenesis by binding to RANKL. The RANK provides critical signals necessary for lymph node organogenesis and osteoclast differentiation. The TNF family molecule OPGL has been identified as a potential osteoclast differentiation factor and regulator of interactions between T cells and dendritic cells in vitro. Thus OPGL is a new regulator of lymph node organogenesis and lymphocyte development and is an essential osteoclast differentiation factor in vivo: So, the result of this study showed that lymph node organogenesis appears to require adequate quantity of RANKL, and this significant level can apparently persist despite marked overexpression of the soluble RANKL inhibitor OPG.

Immunological and molecular detection of digenetic infections in different species of Egyptian freshwater snails.

Due to the possibility of utilizing different snails in the combat of Schistosoma in Egypt; it is important to study the role it may play in transmitting other trematodes of medical and veterinary importance. Taking this background into consideration, polymerase chain reaction (PCR) assay was designed to identify trematode species at larval stages in intermediate hosts (cercariae in snails) using a combination of standard and molecular methods. This PCR assay was also applied to naturally infected molluscan in order to assess the use of the procedure for detection. The importance of the present study was to demonstrate the epidemiological situation and application in control.

Immune response of mice infested by Hyalomma dromedarii ticks infected with entomopathogenic nematodes.

In the present work, the total leucocytes count of infested mice with ticks Hyalomma dromedarii infected with nematodes showed significant increase than infested group with ticks only. The infested group of mice with ticks and infested mice with ticks and nematodes showed a markedly significant drop in the erythrocytes count. The results showed a highly significant decrease in Hb concentration, and HCT percentage for mice infested with ticks and a marked increase with ticks infected with nematodes. The results showed a significant decrease in level of IgG of mice infested with ticks, while in infested mice with ticks and nematodes, the IgG level increased to control level which might indicated that nematodes penetrate ticks that were feeding on mice through the thinner cuticle of engorging females. Differences in cytokines responses were observed between tick-infested and non-infested mice. Proinflammatory Thl T lymphocyte cytokines were suppressed and Th2 cytokines were enhanced for infestation with H. dromedarii. The data indicated a polarization of immune response towards Th2 lymphocytes.

Association of immune responses to mycobacterium tuberculosis peptide antigens with host genetic factors.

A polymerase chain reaction (PCR), based on insertion sequence IS6110, was developed to detect Mycobacterium tuberculosis complex organisms in the blood samples of 56 tuberculosis patients and 34 healthy controls. The early secreted antigenic target 6-KDa (ESAT-6) are used to stimulate T lymphocyte subsets from tuberculosis-infected patients and the correlation of these immune responses to the genetic factors (HLA type) which determined the host immune response is evaluated. ESAT-6 derived peptides: P1 (1.05+/-0.084), P2 (1.08+0.094), P3 (1.02+ 0.086), P5 (0.98+/-0.117) & P7 (1.26+/-0.152) were significantly higher in the infected group than in non-infected one. Besides, 33 patients and 12 controls were tested for HLA-DRB, HLA-DQB1 & HLA-DPB1. Only type HLA-DRB1*15 was significantly associated with tuberculosis infection using the Chi- square test (X(2)=0.04311). By using the relative risk, some HLA types were relatively more susceptible to be associated with tuberculosis infection. HLA-DR typing of patients showed that they covered a large spectrum of HLA-DR molecules encoded by HLA-DRB1, -DRB3, -DRB4, & -DRB5 genes. However, HLA-DQ typing showed that they covered the HLA-DQB1 molecules. HLA-DP typing of patients showed that they covered a large spectrum of HLA-DP molecules encoded by HLA-DPB 1.

Alterations of immune functions in heroin addicts.

The alteration of peripheral blood T-and B-lymphocyte proliferative responses were determined during different periods of withdrawal in heroin (Hw) and heroin / bhang (HBw) addicts. The results clearly demonstrated a significant decrease in the response of T- lymphocytes to PHA-stimulation and secretion of IL-2 in both Hw and HBw addicts. The in vitro presence of naloxone induced further inhibition of the PHA proliferative response and IL-2 production. Our data also indicated a significant suppression of IFN-gamma levels by human blood lymphocytes from Hw and HBw addicts. Additionally, a significant suppression of IFN-gamma production was demonstrated in the presence of naloxone. Moreover, IL-4 production was suppressed in Hw, but not in HBw groups and the in vitro presence of naloxone did not affect the level of IL-4 in both groups. However, IL-10 production was significantly increased in both groups accompanied by a significant suppression of IL-10 secretion in the presence of naloxone. In contrast, IL-5 levels stimulated by PHA showed a significant increase in both groups, while no significant effect of naloxone could be observed. Our results suggested that heroin administration can cause measurable suppression of some components of the human cellular immune system. The results further demonstrated that the immunsuppressive effect observed after heroin use are naloxone-mediated and suggested that activation of the adrenal gland is one potential mechanism for this effect.

Biomphalaria alexandrina: cellular responses of susceptible and resistant snails to Schistosoma mansoni infection.

Distribution pattern of Schistosoma mansoni miracidia level of host susceptility/resistance and the basic cellular responses brought into play during the parasite development. Several snail stocks showed a wide spectrum of host reaction to the parasite. From the present study, a vigorous "resistant-type" cellular response to invading miracidia is seen in the histological sections of non-susceptible snails. In this respect, they were classified in our study as "resistant snails". B. alexandrina experimentally infected with S. mansoni exhibit a wide range of histopathological and immunological changes. The rate of phagocytosis as well as the actual number of hemocytes were determined in different groups of snails during the infection cycle. The significant fluctuation (increase and/or decrease) in circulating hemocyte number was only correlated with a shift in hemocyte populations in the first two days after exposure to the infective stage. The in vitro phagocytic activity of resistant snail hemocytes was found to be higher than that observed in susceptible snails. The observed phagocytic activity indicates that susceptible snail hemocytes were capable of recognizing parasite antigen in vitro, despite of that, they were not able to clear the infection in vivo. Thus suggesting the presence of endogenous factors preventing the immune system of susceptible snails from destroying the developed parasite larvae. Therefore, the mechanism underlying the susceptibility of the snails should be investigated by studying the host-parasite interactions.

A possible role for an enkephalinergic system in the internal defense mechanism of Biomphalaria alexandrina exposed to Schistosoma mansoni.

The present study documents that in Bioniphalaria alexandrina coordinated responses to Schistosoma mansoni infection are modulated by receptor-mediated opioid signals. Rather comprehensive tests in susceptible and resistant snails have demonstrated: I- the presence of an endogenaus opioids in the snail hemolymph (in particular, Leu-enkephalin-like material). II- in vitro treatment of snail hemocytes with synthetic Leu-enkephalin analogue (DADLE) resulted in the modulation of cellular adherence, and phagocytic activity. III- the addition of Naloxone, either alone or in combination whith DADLE, generally reduced hemocyte activity indicating opioid-receptor-mediated mechanism. V- the presence of DADLE or Naloxone modulated the level of IL-2-, TNF-gamma- and FNF-alpha-like molecules in S. mansoni resistant and susceptible snails. Specifically, DADLE and DADLE in combination with Naloxone generally were found to be capable of modulating resistant snail hemocytes at concentrations of 10(-6) and 10(-8) M. Similar actions after incubation with the same concentrations were not detected in the susceptible snails. These observations demonstrate the existence of a complete opioid system in B. alexandrina, associated with susceptibility and resistance to S. mansoni infection, the results suggest the role of such opioid system in molecular signaling within the host and in host-parasite interactions.

Cellular and humoral immune responses to recombinant Smp17.7 Schistosoma mansoni antigen.

To determine the immunological responses to S. mansoni antigen rSmp17.7, a total of 184 subjects, 174 patients from a schistosomiasis endemic area, and 10 controls were used. Proliferation, cytokine profile in culture supernatants from antigen-stimulated peripheral blood mononuclear cells and specific IgG1, IgG3, IgG4, IgA, IgM & IgE levels were assessed. The highest stimulation index to rSmp17.7 was detected in S. mansoni patients. The evaluation of the cytokine profile [IL-2, IL-4 & IFN-gamma] in response to this antigen showed a significant increase as demonstrated by ELISA. Specifically, IFN-gamma and IL-2 were significantly detected by flow cytometry. IgG1 and IgM were the only Igs which showed a significant increase. These results highlight the importance of rSmp17.7 as a candidate vaccine for schistosomiasis. The results pave the way to understand the mechanism of schistosome-vaccine efficacy.

Ultrastructure of phagocytic cells in the spleen of Psammophis sibilans (serpentes: Colubridae).

The spleen of Psammophis sibilans is composed mainly of red pulp, the white pulp being poorly developed. The white pulp lymphoid clusters are scattered throughout the organ and contain lymphocytes, reticular cells, and some plasma cells. The red pulp consists of reticular cells intermingled with blood cells, sinusoids, and melanomacrophage centers (MMCs). Filtering of particulate matter from the blood occurs in the red pulp by phagocytes of the pulp cord. MMCs are formed by the association of free macrophages that have phagocytosed some blood cells. Early filtering of particulate matter by the phagocytes of the pulp cords may allow for more efficient phagocytosis of erythrocytes by the MMCs. © 1994 Wiley-Liss, Inc.