Potential control of the infective stage of Taenia pisiformis using Bacillus thuringiensis GP526 strain.

The GP526 strain of Bacillus thuringiensis has been referred as an in vitro helminthicide on various stages of Dipylidium caninum and Centrocestus formosanus. Our study addresses the in vitro ovicidal activity of GP526 strain spore-crystal complex on Taenia pisiformis eggs, evaluating induced damage microscopically. The eggs exposed to the total extract containing spores and crystals show damage after 24 hours, with loss of integrity on the eggshell, and an ovicidal activity of 33% at 1mg/ml. The destruction of the embryophore was observed after 120 h with a 72% of ovicidal activity at 1 mg/ml. The LC50 was 609.6 µg/ml, dose that causes a 50% of lethality on the hexacanth embryo, altering the oncosphere membrane. The spore-crystal proteins were extracted, and the protein profile was obtained by electrophoresis, finding a major band of 100 kDa suggestive of an S-layer protein, since an S-layer was immunodetected in both, spores and extracted proteins. The protein fraction containing the S-layer protein presents adhesion to the T. pisiformis eggs, and 0.4 mg/ml of the protein induces a lethality of 21.08% at 24 h. The characterization of molecular mechanisms of ovicidal activity will be an important contribution, so the characterization of the proteins that make up the extract of the GP526 strain, would be useful to support the biological potential for control of this cestodiasis and other parasitosis. B. thuringiensis is shown as a potent helminthicide on eggs, with useful potential for biological control of this cestodiasis.

Histometric and morphological damage caused by Serratia marcescens to the tick Rhipicephalus microplus (Acari: Ixodidae).

Rhipicephalus microplus tick is the ectoparasite causing the greatest economic losses in the livestock industry. Multi-resistance in ticks is increasing, generating the inefficiency of traditional ixodicides, for which biological control has been proposed as an alternative. In this work, we analyze the histomorphological damage caused by the bacterial strain EC-35 on Rhipicephalus microplus. The ixodicidal effect of EC-35 total protein was evaluated on larval or adult ticks comparing with the commercial ixodicide coumaphos 0.02% as a control. Female ticks were processed using the paraffin-embedding technique and stained with hematoxylin-eosin. Also, the pathogenicity of EC-35 was evaluated by capillary feeding and coelom inoculation tests. The identification of the bacterium was performed using the molecular markers 16S RNA and rpoB, by PCR and sequencing technique, and the evolutionary distance was analyzed by Bayesian phylogenetic inference. No differences were observed in the perimeter and area of larvae treated with EC-35 or Coumaphos. The thickness of the integument decreased a 65% with the EC-35 treatment (6.01 ± 0.6 µm) and of 30% in coumaphos (12.04 ± 1.2 µm) in larvae compared with the control group (18.41 ± 2 µm), while no difference was found in adult ticks. The capillary feeding test and coelom inoculation with EC-35 showed an inhibition of reproductive potential of 99.8 ± 7 and an oviposition Inhibition 97 ± 3.02%. The EC-35 strain was genetically related to Serratia marcescens, concluding that these bacteria caused high mortality, oviposition Inhibition, and integument thinning and drastic loss of histoarchitecture in R. microplus tick larvae.

Nematicidal Effect and Histological Modifications Induced by Hydrolysable Tannin Extract on the Third-Stage Infective Larvae of Haemonchus contortus.

Haemonchus contortus is the most frequent and most important nematode parasite in the ruminants production of tropical and subtropical regions. There are strains resistant to all families of available anthelmintics. Consequently, the conduction of research to find other resources that allow effective control of this parasitic disease, preferably focusing on green production, is necessary. The aim of this study was to evaluate the effect of hydrolysable tannin extract (HTE) on larvae 3 (L3) of H. contortus in vitro. L3 were exposed to different HTE concentrations and times. In addition, both light and scanning electron microscopy were used to explore physical damage on L3 subjected to HTE activity. After 72 h of incubation, the mean lethal concentration of HTE was 2 mg/mL; this concentration has been previously referred to as safe for consumption in cattle. Scanning electron microscopy revealed H. contortus L3 destruction, damage was evident by separation of the sheath mainly in the cervical and caudal regions of the larva and by rupture of the cuticle with larval evisceration. Our results suggest that hydrolysable tannin extract from chestnut could be considered as a green alternative for parasitic control in ruminants.

Effects of Taenia Pisiformis Infection and Obesity on Clinical Parameters, Organometry and Fat Distribution in Male Rabbits.

Taenia pisiformis infection causes important economic loss in farms. It is suggested that obesity has a major impact on infection and reproduction. We addressed the impact of T. pisiformis infection in normal and obese rabbits to evaluate its effect on parameters important in behavior and reproduction. T. pisiformis infection in obese rabbits decreased body weight. In the obese-infected rabbits, eosinophils and heterophiles were increased 23% by the infection (P ≤ 0.05). T. pisiformis decreased cholesterol by 13% in normal weight infected rabbits and 10% in obese group (P ≤ 0.05), while triglyceride and VLDL were increased by 23% and 45% in the non-infected obese group (P ≤ 0.05). The infection increased serum cortisol levels only in normal weight rabbits (P ≤ 0.05). Liver weight was 20% higher in obese and obese-infected rabbits (P ≤ 0.05). Testicular weight in obese-infected was 46% higher than normal weight (P ≤ 0.0001) and 20% more than the obese-non-infected (P ≤ 0.0001). Furthermore, the infection reduced the weight of submandibular glands in infected and obese-infected rabbits (P ≤ 0.05), body fat increased 10% in the obese-infected than in the obese, and infected group was 35% over the normal weight non-infected (P ≤ 0.01). Our results show that T. pisiformis alters metabolic characteristics in rabbits, which can impact on the production and welfare of animals.

Nematicidal and ovicidal activity of Bacillus thuringiensis against the zoonotic nematode Ancylostoma caninum.

Ancylostoma caninum is a gastrointestinal parasite that affect dogs and humans, considered a worldwide public health problem. The control of these parasitosis is increasingly difficult due to the development of multi-drug resistance. Bacillus thuringiensis is an insecticidal, spore forming bacterium, often species specific. The strain GP526 of B. thuringiensis has toxic effect on the cestode Dipylidium caninum and the trematode Centrocestus formosanus, both of them zoonotic parasites. The high degrees of specificity and environment safe make B. thuringiensis suitable for use against pathogen parasites, especially those resistant to synthetic chemical insecticides. The objective of the current work was to evaluate the in vitro effect of B. thuringiensis on Ancylostoma caninum. Spore-crystal mixture of the strains was co-incubated with 120 adult nematodes (males, non-pregnant females and pregnant females) or with 4800 eggs. GP526 showed a nematicidal effect with an LT50 of 35.8 h and an LC50 of 60 µg/ml. It also showed an ovicidal effect with an LC50 of 94.9 µg/ml. Histological analyses showed detachment of the cuticle and of the uterus in adult females, and vacuolization with destruction of the eggs. The effects of GP526 strain were comparable to those of albendazole, allowing us to propose GP526 for A. caninum control, in both, the adult stage at a gastrointestinal level, and in egg stage in the environment. In addition, GP526 can be proposed as a potential broad spectrum antiparasitic drug.

Influence of the interaction between cysticercosis and obesity on rabbit behavior and productive parameters.

Parasites induce behavioral changes in the host and obesity is a health problem affecting different animal species. Cysticercosis caused by Taenia pisiformis affects some behavior of rabbits and reproductive behavior of does. Rabbits do not escape from metabolic disorders, being long-live animals useful in breeding, research and companion animals. Here, we addressed the interaction between parasitosis and obesity, and studied how these conditions or the comorbidity affect behavioral and productive parameters in bucks infected with 3000 T. pisiformis eggs. We found that the chronic infection reduced locomotor activity by 28.5% in obese, 18.5% in infected and 47% in obese-infected group (comorbid). The exploratory activity reduced by 42% in obese, 48% in infected and 68% in comorbid rabbits (P ≤ 0.001). Chinning was not affected by obesity, while infection decreased it by 25%. Behavioral reproductive parameters like response time, the mount latency and number of ejaculates were affected by infection and obesity. Furthermore, obesity seems to increase the parasite load promoting the formation of liver granulomas (16% granulomas compared with normal weight), with a higher number of cysticerci in obese animals (86% more than normal weight). Infection decreases body weight, body mass index and the zoometric index BW/LV in obese and normal weight rabbits. In conclusion, infection with T. pisiformis altered behavioral and productive parameters, and obesity magnifies the impact caused by the infection. Also, obesity leads to major susceptibility to infection with T. pisiformis.

Anthelmintic effect and tissue alterations induced in vitro by hydrolysable tannins on the adult stage of the gastrointestinal nematode Haemonchus contortus.

Haemonchus contortus constitutes a severe problem for ruminant's production, it is the most frequent nematode parasite both in template and tropical regions, induces economical losses, and shows increasing resistance to currently available anthelmintics. Tannins are secondary metabolites that naturally fulfill defense functions in plants, representing a non-conventional, natural alternative in the treatment of gastrointestinal parasites in sheep. The objective of this work was to explore the in vitro anthelmintic activity of hydrolysable tannins on adult stage of Haemonchus contortus. Adults nematodes were obtained directly from the abomasum of ovines, and a dose response curve was performed with tannins extract at 0, 2, 4, 8, 25 and 50 mg/mL, and a time response curve at 0.5, 1, 2 and 24 h at 37 °C. Hydrolysable tannins decreased motility and induced mortality of H. contortus. We observed cuticle disruption around the mouth and reproductive organs, as well as evisceration. After 24 h of exposition, 8 mg/mL induced 83% of mortality and with 25 mg/kg 100% of mortality was achieved. The LD50 was 3.54 mg/mL, while LD90 was 10 mg/mL. We propose hydrolysable tannins as an alternative to contribute in the nematode control in ruminants.

Behavioural and productive response to experimental infection with stage 3 larvae of Haemonchus contortus in feedlot bull-calves.

Haemonchus contortus is a nematode parasite that establishes in the abomasum of ruminants, it has a cosmopolitan distribution and is a worldwide health problem for livestock. As a first line of defence against parasites, behaviour can help to prevent or fight infection, and may even serve as a method of early presumptive diagnosis. Parasites can affect performance of cattle and cause significant economic losses. The aim of this study was to determine the behavioural and productive changes induced by an experimental infection with H. contortus L3 in bovines. We used 32 dewormed bull calves, randomly divided into two groups, 8 no inoculated controls and 24 that were inoculated with 4000 L3 of H. contortus. Inoculation did not influence haematocrit or haemoglobin values at 0, 28 and 42 days post infection (P> 0.20); however, an increase in the frequency of urination (P = 0.0001) and defecation (P = 0.0001), number of steps (P < 0.001) and self-grooming (P < 0.01) events were observed, even in inoculated animals in which not parasite eggs were found in faeces. During the first 28 days post-inoculation with H. contortus, feedlot performance was not affected (P = 0.16), but during the last 14 days (29-42) inoculated animals gained 15% less weight compared to controls (P = 0.04). Over 42 days, inoculated calves showed a 28% poorer feed efficiency during the 42 days post-inoculation than controls (P < 0.01). Across the experiment, calves inoculated with H. contortus obtained less net energy both for maintenance as for gain from diet (P < 0.01). It is concluded that both, performance and behaviour were modified in feedlot bull-calves parasitized by H. contortus, supporting the practice of deworming when eggs of this parasite are detected in the faeces even in low amounts.

Therapeutic use of Bacillus thuringiensis in the treatment of psoroptic mange in naturally infested New Zealand rabbits.

Bacillus thuringiensis is a bacteria known for its bioinsecticidal toxins and it has been proposed as an alternative in the treatment of several parasites that infect domestic animals (helminths, ticks, mites). In this work, we evaluated the clinical efficiency of the Bacillus thuringiensis GP532 strain in the treatment of six rabbits naturally infested with the P. cuniculi mite. GP532 extract (10mg/ml) was applied by aspersion in both pinna, with a second application after seven days, and the therapeutic effect was measured in both qualitative and quantitative manner. GP532 application resulted in a decreased infestation rate, which was observed as early as 3days post-treatment. At day 14, a decrease from 4.66±0.61 to 0.50±0.10 in the left pinna and from 1.66±0.21 to 0.66±0.16 (P<0.05) in the right pinna was observed. This response was comparable to the commercial drug Ivermectin, which induced a decreased infestation rate from 4.00±0.51 to 0.16±0.10 in the left pinna and from 4.66±0.80 to 0.25±0.11 in the right pinna (P<0.05). At day 30 post-treatment, GP532 decreased the total infested area by 76.80±16.06%, whereas Ivermectin resulted in a 97.41±0.99% decrease. Neither treatment produced irritation or macroscopic lesions. Our results show that the B. thuringiensis GP532 strain has a therapeutic potential in the treatment of psoroptic mange in rabbits.

Taenia pisiformis cysticercosis induces decreased prolificacy and increased progesterone levels in rabbits.

Reproductive alterations in hosts infected by parasites have been recognized in several phyla, especially in arthropods and mollusks, but it has been less studied in higher vertebrates, particularly in mammals. In the present study, ten eight week-old female New Zealand rabbits (Oryctolagus cuniculus) were either infected with Taenia pisiformis eggs or uninfected, and 7 weeks later they were mated. We found that serum progesterone levels were increased during pregnancy in infected does. At birth, litter size of infected does was reduced by half as compared to the control group, and, at weaning, the number of kits and the weight of litters was lower. Since serum progesterone levels have a key role in the maintenance of pregnancy and implantation, we propose that the observed prolificacy alterations in does infected with T. pisiformis infection were due to changes in the levels of circulating progesterone during pregnancy.

Behavioral and hormonal changes associated with the infective dose in experimental taeniasis in golden hamsters (Mesocricetus auratus).

INTRODUCTION: It has been reported that behavioral changes relate to infection in different parasitoses. However, the relation between the extent of the behavioral changes and the magnitude of the infection has been scarcely studied. The aim of this study was to evaluate the relationship between different doses of infection and the behavioral changes induced in the experimental Taenia pisiformis taeniasis in golden hamsters. METHODS: Groups of nine hamsters were infected with three or six T. pisiformis metacestodes. The locomotor activity was quantified daily in an open field test during the 21 days after infection; anxiety test was performed in an elevated plus-maze with a dark/light area at 7, 14 and 21 days post-infection, and serum cortisol levels were determined by radioimmunoassay before infection and at day 22 after infection. RESULTS: The challenge itself induced modifications on behavior and cortisol levels in hamsters, with or without successful infection (taenia development). Animals challenged with three metacestodes induced a decrease in locomotor activity and an increase in anxiety in infected animals. A higher and earlier decrease in locomotor activity and increased anxiety levels were observed in hamsters challenged with six cysticerci, which were accompanied by higher levels of sera cortisol at the end of the experiment. At necropsy, 44-55% of hamster became infected with an efficiency of implantation of 22-26%, challenged with three or six cysticerci respectively. CONCLUSION: The challenge of hamsters with metacestodes, promote behavioral changes in an extent dependent on the magnitude of the challenge, disregarding the effectiveness of the infection.

Acaricidal effect and histological damage induced by Bacillus thuringiensis protein extracts on the mite Psoroptes cuniculi.

BACKGROUND: The mite Psoroptes cuniculi is a common worldwide ectoparasite and the most frequently found in rabbit farms. It causes significant economic losses on commercial rabbit breeding associated with poor leather quality, reduced conception rates, weight loss, poor growth and death. Several strategies have been proposed for the treatment of mange caused by this mite, ranging from the use of acaricides, entomopathogenic fungi, essential oils and vaccines. However, therapy and control of both human scabies and animal mange are still based mainly on the use of drugs and chemicals such as ivermectin, which involves disadvantages including genotoxic and cytotoxic effects, resistance and environmental damage. Bacillus thuringiensis is a bacterium, innocuous for human being, domestic animals and plants that produces highly biodegradable proteins, and has been used worldwide for biological control. The aim of this work was to find an alternative treatment based on biological control for scabies caused by Psoroptes cuniculi, using protein extracts from strains of Bacillus thuringiensis. METHODS: P. cuniculi mites were obtained from naturally infected New Zealand rabbits, and different doses of protein from B. thuringiensis were added to the mites. We measured mortality and obtained the median lethal concentration and median lethal times. For histological analysis, the mites were fixed in 10% formalin, processed according to the paraffin embedded tissue technique. Sections were stained with hematoxylin-eosin to observe the general histological structure. RESULTS: We report here for the first time evidence about the in vitro acaricidal effect caused by the strain GP532 of B. thuringiensis on the mite Psoroptes cuniculi, with an LC50 of 1.3 mg/ml and a LT50 of 68 h. Histological alterations caused by B. thuringiensis on this mite, included the presence of dilated intercellular spaces in the basal membrane, membrane detachment of the peritrophic matrix and morphological alterations in columnar cells of the intestine. CONCLUSIONS: Since this mite is an obligate ectoparasite that affects rabbits, goats, horses, cows and sheep, B. thuringiensis protein extracts are proposed as a potential treatment for biological control of mange in farm animals.

Hormonal and behavioral changes induced by acute and chronic experimental infestation with Psoroptes cuniculi in the domestic rabbit Oryctolagus cuniculus.

BACKGROUND: Parasitic diseases are important in animal production because they cause high economic losses. Affected animals often exhibit stereotypical behavioral alterations such as anorexia and inactivity, among others. Among the diseases that commonly affect domestic rabbits is mange, which is caused by the mite Psoroptes cuniculi. Therefore, within the context of the host-parasite relationship, it is critical to understand the mechanisms involved in the alteration of host behavior, in order to better utilize sick animal behavior as a strategy for diagnosis and treatment of disease. METHODS: Rabbits were infested placing mites in the ear conduct. We characterized changes in exploratory behavior and scent marking evoked by acute (1-9 days) and chronic (25-33 days) experimental infestation. Behavior was recorded during ten minutes while the animals were in a 120 cm × 120 cm open field arena divided into 9 squares. Serum cortisol was measured individually using radioimmunoassay kits. Locomotor activity, chinning, rearing and body weight were compared using a Friedman test, the effect of treatment (infested versus non-infested) across time was analyzed using a repeated measures ANOVA, and the Pearson test was used to determine whether chinning and ambulation scores were significantly correlated. Serum cortisol levels and food consumption were analyzed with a Kruskal-Wallis test and body temperature was analyzed with an ANOVA test. RESULTS: We observed a significant decrease in rearing behavior as early as two days post-infestation, while chinning and locomotor activity were significantly decreased four days post-infestation. Chronic infestation was associated with decreased food intake, significant weight loss, and a trend toward increased serum cortisol levels, while no changes were observed in body temperature. CONCLUSIONS: The presence of visible lesions within the ear canal is commonly used to detect mite infestation in rabbits, but this is possible only after chronic infestation. The behaviors described here may be a useful and economic tool in guiding the early diagnosis of parasitic infestation by P. cuniculi, allowing for early treatment and the application of control measures before significant weight loss occurs, thereby avoiding economic losses.

Macroscopic morphometric analysis of genital organs of rabbit does with differing parturitions at 24 hours post-weaning / Análisis morfométrico macroscópico de órganos genitales de conejas con diferentes partos a las 24 horas post-destete

The purpose of this study was to analyze the macroscopic morphometry of the ovaries, uterus and vagina in rabbit does in the first, second and third parturition at 24 hours post-weaning in order to determine if there are differences between parturitions. Weaning of the litter was performed at 30 days post-partum and 24 hours later the does were euthanized. Right and left ovaries, uterine horns-cervix and vagina were removed, and the length of each one was measured. Significant differences were found in the average of the right ovary length between the first group with respect to second and third parturition group (P 0.05 and P 0.01). Also, left ovary length was different between the first and second with respect to third parturition group (P <0.001). Average total ovary length increased significantly as the number of parturitions increased in second and third parturition groups (P 0.01 and P0.001). The weight of the left and right ovaries was higher in does in their second and third parturition when compared to those in their first (P 0.5; P 0.01). The average total ovary weight increased significantly as the number of parturitions in second and third parturition groups (P0.001). The length of the left and right uterine horn-cervix of the rabbits after second and third parturition decreased when compared to that of females in their first parturition (P 0.05; P0.001). The average total uterine horns-cervix length decreased significantly as the number of parturitions in second and third parturition groups (P0.001). Furthermore, vagina length in females in their third parturition was greater than that of first and second parturition (P 0.01).The color of the vulva of the majority of females in their first parturition (3/4) was pale pink while. In contrast, the majority of females in their second parturition (3/4) had their vulva intensely red. All of the females (4/4) in the third parturition group had their vulva intensely red...

El propósito de este estudio fue analizar la morfometría macroscópica de los ovarios, útero y vagina en conejas de primero, segundo y tercer parto a las 24 horas post-destete con el propósito de determinar si existen diferencias entre los partos. El destete de la camada se realizó a los 30 días después del parto y 24 horas después fueron eutanasiadas. De cada animal se removieron los ovarios derecho e izquierdo, cuernos-cuello uterinos derecho e izquierdo y la vagina y se midió la longitud de cada uno de los órganos genitales. Se encontraron diferencias significativas en la longitud del ovario derecho entre el grupo de primer parto con respecto al de segundo y tercer parto (P 0,05 y P 0,01). Además, la longitud media de ovario izquierdo fue significativamente diferente entre el grupo de primero y segundo parto con respecto al de tercer parto (P <0,001). La longitud total de los ovarios aumentó con el número de partos y fue mayor en los grupos de segundo y tercer parto (P 0,01 y P 0,001). El peso de los ovarios derecho e izquierdo fue mayor en el grupo de segundo y tercer parto al compararlo con el de primero parto (P 0,5; P 0,01). Por otra parte, el peso total de los ovarios aumentó en los grupos de segundo y tercer parto (P 0,001). La longitud del cuerno-cuello uterino izquierdo y derecho de los grupos de segundo y tercer parto disminuyó al compararlo con el de las hembras de primer parto (P 0,05; P 0,001). La longitud total del cuerno-cuello uterino izquierdo y derecho disminuyó significativamente en las hembras de segundo y tercer parto (P 0,001). La longitud de la vagina de hembras de tercer parto fue mayor que la de primero y segundo parto (P 0,01). El color de la vulva de la mayoría de las hembras de primer parto (3/4) fue rosa pálido. En contraste, la mayoría de las hembras en su segundo parto (3/4) presentaron vulva de color rojo intenso. Todas las hembras del grupo de tercer parto (4/4) presentaron vulva de color rojo intenso...

In vitro ovicidal and cestocidal effects of toxins from Bacillus thuringiensis on the canine and human parasite Dipylidium caninum.

Bacillus thuringiensis is a gram-positive soil-dwelling bacterium that is commonly used as a biological pesticide. This bacterium may also be used for biological control of helminth parasites in domestic animals. In this study, we evaluated the possible ovicidal and cestocidal effects of a total protein extract of B. thuringiensis native strains on the zoonotic cestode parasite of dogs, Dipylidium caninum (D. caninum). Dose and time response curves were determined by coincubating B. thuringiensis proteins at concentration ranging from 100 to 1000 µ g/mL along with 4000 egg capsules of D. caninum. Egg viability was evaluated using the trypan blue exclusion test. The lethal concentration of toxins on eggs was 600 µ g/ml, and the best incubation time to produce this effect was 3 h. In the adult stage, the motility and the thickness of the tegument were used as indicators of damage. The motility was inhibited by 100% after 8 hours of culture compared to the control group, while the thickness of the cestode was reduced by 34%. Conclusively, proteins of the strain GP526 of B. thuringiensis directly act upon D. caninum showing ovicidal and cestocidal effects. Thus, B. thuringiensis is proposed as a potential biological control agent against this zoonosis.

Effective protection induced by three different versions of the porcine S3Pvac anticysticercosis vaccine against rabbit experimental Taenia pisiformis cysticercosis.

In an effort to develop an effective and affordable oral vaccine against porcine Taenia solium cysticercosis, the S3Pvac anti-cysticercosis vaccine was expressed in papaya calli. Taenia pisiformis experimental rabbit cysticercosis was used as a model to compare the efficacy of the oral vaccine vs. the injectable S3Pvac-synthetic and S3Pvac-phage versions. Oral S3Pvac-papaya significantly reduced the expected number of hepatic lesions and peritoneal cysticerci to a similar extent than the injectable vaccines. This study reports for the first time an effective oral vaccine against T. pisiformis cysticercosis, possibly useful against porcine T. solium cysticercosis.

A new MAP kinase protein involved in estradiol-stimulated reproduction of the helminth parasite Taenia crassiceps.

MAP kinases (MAPK) are involved in the regulation of cellular processes such as reproduction and growth. In parasites, the role of MAPK has been scarcely studied. Here, we describe the participation of an ERK-like protein in estrogen-dependent reproduction of the helminth parasite Taenia crassiceps. Our results show that 17beta-estradiol induces a concentration-dependent increase in the bud number of in vitro cultured cysticerci. If parasites are also incubated in presence of an ERK-inhibitor, the stimulatory effect of estrogen is blocked. The expression of ERK-like mRNA and its corresponding protein was detected in the parasite. The ERK-like protein was over-expressed by all treatments. Nevertheless, a strong induction of phosphorylation of this protein was observed only in response to 17beta-estradiol. Cross-contamination by host cells was discarded by flow cytometry analysis. Parasite cells expressing the ERK-like protein were exclusively located at the subtegument tissue by confocal microscopy. Finally, the ERK-like protein was separated by bidimensional electrophoresis and then sequenced, showing the conserved TEY activation motif, typical of all known ERK 1/2 proteins. Our results show that an ERK-like protein is involved in the molecular signalling during the interaction between the host and T. crassiceps, and may be considered as target for anti-helminth drugs design.

Syk and Lyn phosphorylation induced by FcgammaRI and FgammaRII crosslinking is determined by the differentiation state of U-937 monocytic cells.

Fcgamma receptor (FcgammaR)-mediated phagocytosis by mononuclear phagocytes is an essential function in host defense. This process is initiated by crosslinking of membrane FcgammaRs, which induces phosphorylation and activation of Src and Syk tyrosine kinases. Activation of these enzymes is essential for initiating the biochemical cascade that results in the cytoskeletal and membrane changes involved in phagocytosis. Phagocytic capacity and other effector functions of mononuclear phagocytes change during differentiation/maturation of these cells. This is a complex process governed by different soluble and micro-environmental factors, giving rise to populations of cells with distinct phenotypic characteristics. Several agents, including calcitriol, have been shown to induce in vitro differentiation-related phenotypic changes in monocytic cell lines. In this paper, we characterized the changes in the initial biochemical signals associated with the increase in FcgammaR-mediated phagocytosis induced by calcitriol in monocytic U-937 cells. The 10-fold increase in phagocytic capacity is not accompanied by an increase in FcgammaR expression. However, the phosphorylation levels of Lyn and Syk after FcgammaRI or FcgammaRII crosslinking are increased after calcitriol treatment. Our results suggest that signaling induced by FcgammaR in mononuclear phagocytes is not only dependent on the quantity of FcgammaRs aggregated by a stimulus, but it is highly dependent on the cell's differentiation state.

Expression of mRNA for interleukin-1beta, interleukin-6, tumor necrosis factor-alpha and macrophage migration inhibitory factor in HPA-axis tissues in Schistosoma mansoni-infected baboons (Papio cynocephalus).

Cytokines may regulate the function of the hypothalamic-pituitary-adrenal axis during schistosomiasis. This possibility was investigated in baboons experimentally infected with Schistosoma mansoni. Serum levels of corticotrophin-releasing hormone, adrenocorticotrophin, cortisol and dehydroepiandrosterone were confirmed to be decreased in infected baboons as previously shown. To explore if this effect is associated with specific expression of cytokines with endocrine activity, and are also associated with the pathology of the disease, Northern blots for interleukin-1beta, interleukin-6, tumor necrosis factor-alpha and macrophage migration inhibitory factor in hypothalamic-pituitary-adrenal axis tissues were performed. Infection induced interleukin-1beta gene expression in the hypothalamus, while interleukin-6 and migration inhibitory factor mRNAs were induced only in the pituitary and adrenal glands. Tumor necrosis factor-alpha gene expression was induced in the hypothalamus and the pituitary gland. Histopathological analysis of the hypothalamic-pituitary-adrenal axis tissues in infected and control baboons revealed no morphological differences between them. These results suggest that specific cytokines expressed in hypothalamic-pituitary-adrenal axis tissues could regulate hormone secretion during schistosomiasis.