Cercarial Antigen Research Articles

The efficacy of cercarial antigen loaded on nanoparticles as a potential vaccine candidate in Schistosoma mansoni-infected mice.

Schistosomiasis is one of the most common causes of morbidity and mortality from parasitic diseases. Mass treatment has proven to be insufficient because of repeated infection after treatment and the appearance of strains resistant to drug therapy. Hence, immunization is a new approach to control the disease and limit the pathological consequences of schistosomiasis. To evaluate the prophylactic effect of Cercarial antigen (CAP) loaded on chitosan nanoparticles (CSNPs) as a potential vaccine against Schistosoma mansoni-infected mice. 130 mice divided into 2 groups were used: Group I: Control groups (50 mice) subdivided into subgroup Ia (10 mice): Non-infected mice (normal control), subgroup Ib (20 mice): Schistosoma infected mice (infected control) and subgroup Ic (20 mice): Non-infected mice receiving NPs only. Group II: Vaccinated group (80 mice) subdivided equally into subgroup IIa (CAP): Received cercarial antigen and subgroup IIb (CAP + CSNP): Received cercarial antigen loaded on chitosan NPs then both vaccinated groups were infected with S. mansoni 3 weeks following the initial vaccination dose. CAP + CSNP and CAP groups showed significant reduction in adult worms count, hepatic egg count, hepatic granulomas number and size in comparison to the infected control group. Elevation of serum IgG and IgM levels, CD4+ and CD8+ T cell frequencies, IL-4, IL-10 and INF-γ levels was more significant in CAP + CSNP group than CAP group. CAP + CSNP is a promising new preparation of Schistosomal antigens that gave better results than immunization with CAP alone. CSNPs enhanced the immune and protective effect of CAP as validated by parasitological, histopathological and immunohistochemical studies.

The Efficiency of Schistosoma mansoni Crude Antigens in Inhibition of Heat Shock Protein, Apoptosis, and Lysosomal Activity: An Immunohistochemical Study.

The adverse impact of schistosomiasis on tissues is considered in generating a schistosomal vaccine. The purpose of this study was to evaluate the effectiveness of Schistosoma mansoni crude antigens as a therapeutic and prophylactic formulation in the inhibition of heat shock protein, apoptosis, and CD3/CD20 expression in a liver and spleen mouse models using the immunohistochemistry method. A total of 65 mice were divided into five groups: (i) infected untreated group (G1), (ii) therapeutic treated group (G2) with egg soluble egg antigen (SEA), and soluble worm antigen preparation (SWAP), (iii) prophylactically treated group (G3) with cercarial antigen preparation (CAP), (iv) combined treated group with three antigens (G4), and (v) control group (G5). The results we obtained showed that CAP, SEA, and SWAP antigens mitigated the deterioration and inflammation induced by infection. Apoptosis and sinusoidal injuries were significantly reduced when treated with CAP antigen before infection. After infection, using SEA and SWAP antigens may help lighten the liver's load. A high degree of activation in T and B cells in the liver and spleen is linked to this. Our findings shed light on the immunological mechanisms that contribute to the recovery from therapy and vaccination against schistosome damage.

Assessment of the Diagnostic Performance of Normal and Irradiated Schistosoma mansoni Cercarial Antigens using ELISA

Assessment of the Diagnostic Performance of Normal and Irradiated Schistosoma mansoni Cercarial Antigens using ELISA

An Insight into the Potential Parasitological Effect ofSchistosoma mansoniAntigens in Infected Mice: Prophylactic Role of Cercarial Antigen

Schistosomiasis is a multifactorial disease that includes environmental, behavioral, parasitic, vector, and host factors. This study aimed to assess the protective effect of single and polyvalent antigens from cercarial antigen preparations (CAPs), soluble worm antigen preparations (SWAPs), and soluble egg antigens (SEAs) which were used as candidate vaccines in an experimental model of Schistosoma mansoni-infected mice. The efficiency of the antigens was tested by determining their effects on fecal egg count, egg viability analysis, and tissue egg counts. Histological and morphometric analyses of granulomas in liver and intestine tissues were performed. In the present study, all immunized groups showed a significant reduction in the average fecal egg count and tissue egg load compared with infected mice. The most substantial reduction in fecal egg count was observed in the combined vaccinated group (23.23 ± 3.2). The group vaccinated with CAP before infection showed the highest reduction in tissue egg load (liver and intestine: 85.22 and 91.70%, respectively). Immunized animals showed a highly significant reduction in the numbers of hepatic granulomas compared with the infected non-immunized group. In conclusion, combining these different antigens (CAP, SWAP, and SEA) augments the protective immunity compared with other immunized groups.

Evaluation of Gamma Radiation-Attenuated Schistosoma mansoni Cercarial Antigens for Immunodiagnosis

DEVELOPMENT of sensitive and specific diagnostic tools for early diagnosis and treatment has an important necessity. This study focuses on identifying and evaluating immunodiagnostic potential of irradiated Schistosoma mansoni cercarial antigens by immunoblot analysis using infected human sera. Forty two serum samples were divided into: 14 sera from S. mansoni infected patients (Group I), 18 sera of patients with other parasitic diseases (Group II) and 10 sera from healthy individuals (Group III). Characterization of normal and 0.4Gy gamma radiation-attenuated cercarial antigens (Cer. Ags) was conducted using Gel Electrophoresis (SDS- PAGE). Normal Cer. Ags was resolved into six individual bands of 205, ≈160, 97, 66, 43 and ≈38kDa while irradiated Cer. Ags. showed same bands except 66kDa, in addition to two more bands which were ≈50 and 24kDa. Immunoblot analysis of irradiated cercarial antigens using pooled sera of patients with schistosomiasis mansoni identified four bands two like normal one, 97kDa and ≈32kDa, in addition to ≈50kDa and 43kDa bands. Total IgG immunoblotting using irradiated cercarial antigens with individual sera of patients with schistosomiasis and other parasites revealed that higher diagnostic accuracy was achieved by both 97kDa and 24kDa with 78.6%. Both 97 and 43kDa bands gave a higher sensitivity of 64.3% while 24kDa bands achieved the highest specificity of 89.3%. It could be concluded that total immunoblotting using irradiated cercarial antigens at 97kDa and 24kDa proved to be valuable as diagnostic tests for human schistosomiasis.

Antigenic cross-reactivity between Schistosoma mansoni and allergenic invertebrates putatively due to shared glycanic epitopes

Previous studies have shown that rabbit IgG antibodies against Schistosoma mansoni egg antigens (SmSEA) cross-react with allergens in natural rubber latex, peanuts and grass and tree pollens. Here we describe antigenic molecules that cross-react with rabbit anti-S. mansoni IgG antibodies in extracts of the house dust mite (HDM) Dermatophagoides farinae, the Australian cockroach (ACR) Periplaneta australasiae and in the venom of the honey bee Apis mellifera (HBV). Tandem mass spectrometry identified the cross-reactive allergens as Der f 15 in HDM, two homologues of the Periplaneta americana cockroach allergen Cr-PI/Per a 3 in ACR and two isoforms of the allergen Api m 1 (phospholipase A2: PLA2) in HBV. Cross-reactive rabbit anti-SmSEA IgG antibodies eluted from the three invertebrate allergens reacted with S. mansoni egg antigens and variably with schistosome cercarial and worm antigens. Treatment of the electroblotted allergens with sodium metaperiodate abrogated most of the cross-reactivity of the rabbit anti-SmSEA antibodies, suggesting it was due to cross-reactive carbohydrate determinants (CCDs). Furthermore, analyses of the allergens’ amino acid sequences indicated that they had potential for both N- and O-linked glycosylation. A potential role for the CCDs shared by the schistosome and invertebrates in inducing an allergy-protective effect, as proposed by the hygiene hypothesis, is discussed.

Elevation of C-reactive protein, P-selectin and Resistin as potential inflammatory biomarkers of urogenital Schistosomiasis exposure in preschool children

BackgroundSchistosomiasis is known to induce inflammatory immune responses. C-reactive protein (CRP), resistin and P-selectin are serological inflammatory markers that rise during the acute stages of infection. Here, we propose such inflammatory biomarkers have a potential for use in urogenital schistosomiasis diagnostic screening for exposure and infection in preschool-aged children.MethodsAs part of a larger study on urogenital schistosomiasis, 299 preschool children aged 1–5 years were included in this cross-sectional study. Parasitological diagnosis was conducted using urine filtration for Schistosoma haemtobium infection, and Kato Katz for S. mansoni infection. Serum levels of P-selectin, resistin, CRP, and antibodies against S. haematobium cercarial antigen preparation (CAP) and soluble worm antigen preparation (SWAP) were measured by ELISA.ResultsOf the 299 participants, 14% were egg positive for S. haematobium. Serology showed 46 and 9% of the participants to have been exposed to S. haematobium cercarial antigens and adult worm antigens, respectively. Levels of P-selectin were significantly higher in participants infected with S. haematobium (egg-positive) than in uninfected participants (p = 0.001). Levels of P-selectin were also higher in those exposed to cercarial antigen than in unexposed participants (p = 0.019). There was a positive correlation between P-selectin and infection intensity (r = 0.172; p = 0.002), as well as with IgM responses to CAP and SWAP (r = 0.183; p = 0.001); (r = 0.333; p < 0.0001) respectively. CRP significantly correlated with IgM responses to CAP (r = 0.133; p = 0.029) while resistin correlated with IgM responses to CAP and SWAP (r = 0.127; p = 0.016); (r = 0.197; p = 0.0004). CRP levels were higher in those exposed to cercarial and adult worm antigens than unexposed participants (p = 0.035); (p = 0.002) respectively, while resistin was higher in participants exposed to cercarial antigen than unexposed participants (p = 0.024).ConclusionIn this preschool population, P-selectin is significantly associated with urogenital schistosome infection and intensity; hence a potential biomarker for infection diagnosis and disease monitoring. The inflammatory biomarkers (P-selectin, Resistin and CRP) were significantly higher in participants exposed to cercarial antigens than unexposed individuals indicating an underlying inflammatory environment.

Cross-Reactivity between Schistosoma mansoni Antigens and the Latex Allergen Hev b 7: Putative Implication of Cross-Reactive Carbohydrate Determinants (CCDs).

IgG antibodies produced by rabbits immunized against S. mansoni antigens cross-reacted with aqueous soluble constituents of a variety of allergens. The antibody cross-reactivity was largely sensitive to degradation by treatment of the target antigens with sodium meta-periodate, suggesting the cross-reactivity was due to carbohydrate determinants that were common to both the schistosome and the allergens (CCDs). The reaction between the rabbit antibodies and a 43 kDa molecule in a rubber latex extract was analysed further: tandem mass spectrometry identified the latex molecule as allergen Hev b 7. Rabbit anti-schistosome IgG antibodies purified by acid-elution from solid-phase latex Hev b 7 reacted with the S. mansoni egg antigens IPSE/alpha-1 and kappa-5 and cercarial antigens SPO-1 and a fatty acid-binding protein. Moreover, purified anti-S. mansoni egg, latex cross-reactive antibodies reacted with antigenic constituents of some fruits, a result of potential relevance to the latex-fruit syndrome of allergic reactions. We propose that IgG anti-schistosome antibodies that cross-react with allergens may be able to block IgE-induced allergic reactions and thus provide a possible explanation for the hygiene hypothesis.

Protective capacity of cercarial transformation fluid alone or in combination with crude cercarial antigen against challenge infections of Schistosoma mansoni in mice.

Schistosomiasis is the second major parasitic disease in the world after malaria. It affects 201.5 million cases in Africa alone. The aim of this research was to explore alternative vaccination strategies against experimental schistosomiasis mansoni. We assessed the effect of cercarial transformation fluid (CTF) singly and in combination with crude cercarial antigen (CCA) using alum as an adjuvant. The combined antigens gave the best results, as evidenced by a significant reduction in the worm load (62.07%), tissue egg count (78.16%, 86.46%) in liver and intestine respectively, and hepatic granuloma size (29.96%). Scanning electron microscopy revealed changes in the tegument, in the form of roughness and appearance of vesicles and furrows between the tegumental tubercles. Also, resorption of the ventral sucker and dimples replacing its spines were observed. The female tegument was irregular and its posterior end showed loss of spines and sensory bulbs. Moreover, there was a significant decrease in liver enzymes (alanine transaminase (ALT) and aspartate transaminase (AST)) compared to infected control mice. A significant elevation in CD4+T-lymphocytes, denoting amelioration of the immune status, in mice that received combined antigens was also observed. It can be concluded that combined antigens demonstrate potential as a vaccine against Schistosoma mansoni.

Antibody response of definitive hosts against antigens of two life stages of the neuropathogenic schistosome Trichobilharzia regenti.

BackgroundThe nasal avian schistosome Trichobilharzia regenti spends part of its intravertebrate period of life within the central nervous system. Migration of the parasites can be accompanied by neuromotor disorders or paralysis in natural definitive hosts (ducks) and even in laboratory mammals. Cercariae are also able to penetrate human skin and induce cercarial dermatitis. While the cellular and antibody responses against cercariae and migrating schistosomula have been investigated in mice, little is known about immune reactions in birds. This study first describes the dynamics of antibody response in infected ducks and identifies frequently recognized antigens that may serve as diagnostic markers of infection by T. regenti.MethodsGroups of 35 domestic ducks and 10 mallards were exposed to different doses of T. regenti cercariae. Sera were collected at predefined time intervals and tested by ELISA for the presence of specific anti-cercarial IgY and IgM. Antigens recognized by the antibodies were identified on Western blots of cercariae and schistosomula. The applicability in immunodiagnostics was statistically evaluated by expression of specificity and sensitivity values for individual antigens.ResultsIn ELISA, the levels of anti-cercarial IgM peaked on day 15 pi. Increased production of IgY associated with the later phases of infection was observed in most individuals around 20 dpi and culminated 30 dpi. The time course of antibody response did not differ among experimental groups, variations were only observed in the levels of specific IgY which depended rather on the age of ducks at the time of infection than on the infectious dose. On Western blots, 40 cercarial and 7 schistosomular antigens were recognized by IgY from infected ducks. Among them, 4 cercarial antigens of 50, 47, 32 and 19 kDa provided the most sensitive and specific reactions.ConclusionsAntigens of cercariae and schistosomula elicited distinct antibody response in ducks, which correlated positively with the age of animals at the time of infection. Several antigens originating in cercariae and fewer in schistosomula were recognized by IgY with diverse sensitivity and specificity; only a few seemed to be common to both stages. Four of them were considered as the most promising candidates for immunodiagnostics.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-1007-y) contains supplementary material, which is available to authorized users.

Studies on the role of tumor necrosis factor- alpha (TNF-α) in hepatocytes induced apoptosis in vaccinated, Schistosoma mansoni-challenged mice.

Tumour Necrosis Factor-alpha (TNF-α) plays a complex role in pathophysiological changes caused by schistosomiasis in the liver cells as induced apoptosis. So, The highlighted experimentally the role of TNF-α in hepatocytes apoptosis, using that as an assessment of the efficacy of antischistosomal vaccination by mixed crude antigens preparations [Cercarial antigen preparation (CAP) + soluble worm antigen preparation (SWAP) + soluble egg antigen(SEA)] by parasitological, histo-pathological and histochemical studies using Feulgen stain of hepatoytes DNA, a serological study also of serum TNF-α level by ELISA. Fifty two laboratory bred Albino male mice, were used in this study. They were classified into four groups (13 mice in each group), G1: normal control, G2 as infected control while G3 supported by Freund's Adjuvant (F. Adj) then infected and G4 vaccinated with combined antigens (CAP, SWAP and SEA) + F. Adj, then infected. Mice were sacrificed by cervical dislocation 9 weeks post infection, parasitological (Kato-Katz thick smear for egg count), histopathologial {haematoxylin and eosin (H&E) staining of hepatic sections}, histochemical (feulgen staining of hepatocytes DNA) and ELISA to estimate serum TNF-α level were performed. The data showed that vaccination with combined antigens showed protective effect on vaccinated then Schistosoma challenged mice, hepatocytes induced apoptosis was directly proportional with the TNF-α serum level, and the protection degree of potential combined vaccine was inversely proportional with serum TNF-α level and induced apoptosis.

Effect of Ultra Violet Attenuated Cercariae on Antibody Response in Rabbits

Ultraviolet (UV) light is an electromagnetic radiation below the visible wavelengths. Their use in cercariae attenuation needs to be examined. In the present work, Schistosoma mansoni cercariae was exposed to UV radiation. Few studies showed previously an inflicted damage seen on the adult schistosome worms developed from irradiated cercariae. The aim of the study was to find out whether this damage was attributed to direct effect of UV-irradiation on cercariae or due to the host's immunogenicity induced by UV- irradiated cercariae. Single as well as multiple exposures of cercariae to UV Light were examined. They were exposed to UV light, for 1, 2 and 3 hrs and then, were subjected to different treatments: the first one was for the assessment of cercarial viability after one hour of the 3 different treatments. The second one was for rabbit infection and the third one was for cercarial antigen preparation. The cercarial antigens (Ag) were recognized by protective antibodies (IgG1 fractions) which then, were separated and purified from vaccinated rabbit's serum. This cercarial Ag was identified as UVISmC1 gene encoding a protein showing 100% identity at the amino acid level with previously identified S. mansoni clones; theses clones are encoding 51.7 kDa antigens elicited as a result of direct effect of UV radiation on cercariae as well as host's immunogenicity induced by UV irradiated cercariae. This was verified by the recognition of this Ag prepared from E coli clones isolated from cDNA expression library. In conclusion, the data showed a remarkable potency of the UV-radiation-attenuated cercaria in eliciting differential high effectiveness in Ab response under laboratory conditions at 1, 2 and 3 hrs of UV light output at 254 nm. An understanding of the protective immune response elicited by RA cercaria may help in designing a candidate vaccine which is still needed.

In vitroandin vivoeffects of hesperidin treatment on adult worms ofSchistosoma mansoni

Hesperidin has been reported to exert a wide range of pharmacological effects, including antifungal, antiviral, antioxidant, anti-inflammatory and anticarcinogenic activities. Herein, the schistosomicidal activity of this compound was evaluated in vitro and in vivo. Using an in vitro assay, a concentration of 200 μg/ml of hesperidin resulted in the mortality of 100% adult worms of Schistosoma (S.) mansoni within 72 h and a partial tegumental alteration in 10% of worms. However, after 144 h incubation, 50 and 100 μg/ml concentrations showed 0% and 10% mortality in adult worms, respectively, without any changes to the tegument. Sublethal doses did not influence egg output nor the development of eggs deposited by pairs of adult worms. In an in vivo study, mice infected with S. mansoni and treated with 600 mg hesperidin/kg body weight showed a respective reduction of 50, 45.2, 50 and 47.5% of males, females, worm pairs and total worm burden. In addition, a respective reduction, based on the number of eggs/g tissue, of 41.5, 63.7 and 58.6% was observed in the liver, intestine and liver/intestinal tissue combined. Furthermore, S. mansoni-specific IgG level significantly increased with hesperidin treatment, whereas IgA and IgE levels were not significantly changed. IgM levels decreased in response to cercarial antigen preparation but were not altered in response to soluble worm or soluble egg antigen. As in hesperidin-treated mice, praziquantel-treated mice showed a similar pattern of specific antibody response to S. mansoni antigens. The present study represents the first report on the effects of the schistosomicidal activity of hesperidin.

Efficacy of L-carnosine against Schistosoma mansoni antigens in liver, heart, kidney and brain of rabbits

Article history: The present investigation was an attempt to study the enhancememt effect of L-carnosine (beta alanyl-l-histidine) on the influence of vaccination on healthy (non-infected) rabbits treated with Schistosoma mansoni egg antigens, cercariae antigens, and worms antigens as protective agents against infection. This study involved individual injection of three Schistosoma mansoni antigens: soluble egg antigen (SEA), cercarial antigen preparation (CAP) and soluble worm antigen preparation (SWAP), in three rabbit groups, respectively. Three other groups each received the same specific antigen in conjunction with the administration of L-carnosine, biochemical parameters including DNA, RNA, DNA/RNA ratio concentrations in addition ATPase, and acetyl cholinesterase activities were measured in liver, heart, kidney and brain in all groups. Elevation in most parameters was observed in the immunized groups. Carnosine treatment of rabbit groups immunized with SEA, CAP and SWAP in comparison to the non-carnosine-treated immunized groups resulted in amelioration the changes of DNA, RNA, ATPase and acetyl cholinesterase activities in most groups. L-carnosine has a beneficial effect in the amelioration of the changes in biochemical parameters as a result of S. mansoni antigen immunization.

Comparison of Schistosoma mansoni Soluble Cercarial Antigens and Soluble Egg Antigens for Serodiagnosing Schistosome Infections

A Schistosoma mansoni cercarial antigen preparation (cercarial transformation fluid – SmCTF) was evaluated for detection of anti-schistosome antibodies in human sera in 4 collaborating laboratories. The performance of SmCTF was compared with that of S. mansoni egg antigens (SmSEA) in an indirect enzyme-immunoassay (ELISA) antigen assay, the latter being used routinely in 3 of the 4 participating laboratories to diagnose S. mansoni and S. haematobium infections. In the fourth laboratory the performance of SmCTF was compared with that of S. japonicum egg antigens (SjSEA) in ELISA for detection of anti-S. japonicum antibodies. In all 4 laboratories the results given by SmCTF in ELISA were very similar to those given by the antigen preparation routinely used in the respective laboratory to detect anti-schistosome antibodies in human infection sera. In so far as the ELISA results from SmCTF are thus so little different from those given by schistosome egg antigens and also cheaper to produce, the former is a potentially useful new diagnostic aid for schistosomiasis.

Inhibitory effect of some new uracil and thiouracil derivatives on cercarial penetration enzymes

Some uracil- and thiouracil-5-sulfonohydrazide derivatives have been synthesized to be evaluated as antischistosomal agents. N-[2-(1,5-Dimethyl-3-oxo-2-phenylpyrazolin-4-yl)-4-oxo-1,3-thiazolidin-3-yl]-4-oxo-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-sulfonamide (3c) was formulated in jojoba oil and used to paint mice tails before infection with Schistosoma mansoni cercariae. Using Boc-Val-Leu-Gly-Arg-PNA, a specific substrate for trypsin-like serine proteinases, compound 3c inhibited cercarial serine protease activity with 50 % inhibition concentration (IC50) of 160 μg. Upon topical application on mice tails before infection with S. mansoni cercariae, it caused a 20 % reduction in worm burden compared with untreated infected mice. Using soluble crude cercarial antigen in enzyme-linked immunosorbent assay (ELISA), no significant changes were observed in the levels of immunoglobulin M (IgM) and IgG in sera from treated infected mice at 2, 4, and 6 weeks postinfection (WPI) compared with the level in sera from infected untreated mice. At 4 WPI, sera from treated infected mice showed significantly low (P < 0.05) IgM reactivity to crude soluble worm antigen compared with infected nontreated ones. IgG levels in sera from treated infected mice at 2 and 4 WPI were significantly lower (P < 0.05) than in sera from infected nontreated mice. At 6 WPI, the IgG response showed no significant differences in sera from both mice groups. Sera from treated infected mice at 2, 4, and 6 WPI had generally lower IgM reactivity to soluble egg antigen when compared with the level in sera from nontreated infected mice. At all time points postinfection, sera collected from treated infected mice showed significantly low IgG reactivity (P < 0.05) compared with infected nontreated mice.

A HIGH POTENT ANTIBODY RESPONSE IN RABBITS INFECTED WITH ULTRA VIOLET ATTENUATED CERCARIAE

Ultraviolet (UV) light is an electromagnetic radiation below the visible wavelengths. Their use in cercariae attenuation needs to be examined. In the present work, Schistosoma mansoni cercariae was exposed to UV radiation. Few studies showed previously an inflicted damage seen on the adult schistosome worms developed from irradiated cercariae. The aim of the study was to find out whether this damage was attributed to direct effect of UV-irradiation on cercariae or due to the host's immunogenicity induced by UV- irradiated cercariae. Single as well as multiple exposures of cercariae to UV Light were examined. They were exposed to UV light, for 1, 2 and 3 hrs and then, were subjected to different treatments: the first one was for the assessment of cercarial viability after one hour of the 3 different treatments. The second one was for rabbit infection and the third one was for cercarial antigen preparation. The cercarial antigens (Ag) were recognized by protective antibodies (IgG1 fractions) which then, were separated and purified from vaccinated rabbit's serum. This cercarial Ag was identified as UVISmC1 gene encoding a protein showing 100% identity at the amino acid level with previously identified S. mansoni clones; theses clones are encoding 51.7 kDa antigens elicited as a result of direct effect of UV radiation on cercariae as well as host's immunogenicity induced by UV irradiated cercariae. This was verified by the recognition of this Ag prepared from E coli clones isolated from cDNA expression library. In conclusion, the data showed a remarkable potency of the UV-radiation-attenuated cercaria in eliciting differential high effectiveness in Ab response under laboratory conditions at 1, 2 and 3 hrs of UV light output at 254 nm. An understanding of the protective immune response elicited by RA cercaria may help in designing a candidate vaccine which is still needed.

Evaluation of the immunological effect of beta alanyl-l-histidine against Schistosoma mansoni antigens in rabbits

The influence of vaccination on healthy (non-infected) rabbits treated with Schistosoma mansoni egg antigens, cercariae, and worms as prophylactic agents against infection, and the benefit of beta alanyl-l-histidine treatment against Schistosoma mansoni infection were investigated. This study involved individual injection of three Schistosoma mansoni antigens: soluble egg antigen (SEA), cercarial antigen preparation (CAP) and soluble worm antigen preparation (SWAP), in three rabbit groups, respectively. Three other groups each received the same specific antigen in conjunction with the administration of (beta alanyl-l-histidine) L-carnosine. Hepatic total protein, glycogen and glycogen phosphorylase, total serum protein and one diminution electrophoresis of protein fractions (180 KDa; 116 KDa; 97, 4 KDa, serum albumin 66 KDa; 48. 5 KDa; 29 KDa; 18.400 KDa; 14.200 KDa; 6.5 KDa) were measured in all the rabbit groups. Elevation in most parameters was observed in the immunized groups. Carnosine treatment of rabbit groups immunized with SEA, CAP and SWAP in comparison to the non-carnosine-treated immunized groups resulted in amelioration of serum protein fractions in all SEA and SWAP-immunized animals, and reduction in glycogen phosphorylase b in SWAP animals alone. In addition, changes in glycogen content were observed in the CAP-immunized group. L-carnosine has a beneficial effect in the amelioration of most biochemical parameters as a result of S. mansoni antigen immunization.

Comparative sensitivities of various tests for diagnosing early Schistosoma mansoni infection in mice

Objective: We compared the diagnostic values of cercarial antigen preparation, cercarial secretions, soluble worm antigen preparation and worm vomit prepared from the parasite Schistosoma mansoni. Methods: Enzyme linked immunosorbant assay was used to detect IgG in plasma from Schistosoma mansoni infected mice. In parallel, specific primers for the parasite genome was used to detect S. mansoni DNA in plasma and urine from infected mice and hemolymph and tissues of infected Biomphalaria alexandrina snails by Polymerase chain reaction. Results: The results showed that all the above diagnostic approaches enabled infection to be diagnosed as early as three days post mice exposure to parasite cercariae. Conclusion: Cercarial secretions and worm vomit represent new useful economic crude antigens for preliminary detection of parasite active transmission or response to therapy in an endemic setting. Also, it was found that the detection of Schistosoma mansoni DNA in urine from infected mice was the most sensitive and specific (although expensive) method for infection diagnosis than all the others.

Immune Responses in Mice after Immunization with Antigens from Different Stages of the Parasite Schistosoma mansoni

Mice responses to immunization with Schistosoma mansoni antigens were investigated. Priming with cercarial antigen preparation (CAP) induced significant (P < 0.05) IgM, IgG, IgG2a, IgG2b, and IgA increases, while booster caused a significant IgG1 increase. A soluble worm antigen preparation (SWAP) caused significant IgG elevation. Priming with soluble egg antigen (SEA) caused significant IgM and IgG2a increases, while booster induced significant IgM, IgG and IgA increases. CAP-immunized mice sera (IMS) recognized CAP peptides ranging from 23-78 kDa. SWAP-IMS recognized SWAP peptides ranging from 40-75 kDa. SEA-IMS recognized SEA peptides ranging from 33-101 kDa. The cross-reactive peptides among the 3 antigens were identified. CAP caused significant increases in mesenteric lymph nodes (MLNs) CD(4,8)+, B lymphocytes, CD8+ thymocytes, CD4+ T and B splenocytes. SWAP priming caused significant increases in MLNs CD(4,8)+ thymocytes and B splenocytes. SWAP booster caused significant increases in MLNs CD8+ T and B lymphocytes, CD(4,8)+ thymocytes and CD4+ T and B splenocytes. SEA caused significant increase in CD4+ T cells.