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.

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.

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.

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.

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.