Cnidarian venoms and extracts have shown a broad variety of biological activities including cytotoxic, antibacterial and antitumoral effects. Most of these studied extracts were obtained from sea anemones or jellyfish. The present study aimed to determine the toxic activity and assess the antitumor and antiparasitic potential of Palythoa caribaeorum venom by evaluating its in vitro toxicity on several models including human tumor cell lines and against the parasite Giardia intestinalis. The presence of cytolysins and vasoconstrictor activity of P. caribaeorum venom were determined by hemolysis, PLA2 and isolated rat aortic ring assays, respectively. The cytotoxic effect was tested on HCT-15 (human colorectal adenocarcinoma), MCF-7 (human mammary adenocarcinoma), K562 (human chronic myelogenous leukemia), U251 (human glyoblastoma), PC-3 (human prostatic adenocarcinoma) and SKLU-1 (human lung adenocarcinoma). An in vivo toxicity assay was performed with crickets and the antiparasitic assay was performed against G. intestinalis at 24 h of incubation. P. caribaeorum venom produced hemolytic and PLA2 activity and showed specific cytotoxicity against U251 and SKLU-1 cell lines, with approximately 50% growing inhibition. The venom was toxic to insects and showed activity against G. intestinalis in a dose-dependent manner by possibly altering its membrane osmotic equilibrium. These results suggest that P. caribaeorum venom contains compounds with potential therapeutic value against microorganisms and cancer.

The giardiasis is a neglected parasitic disease. The WHO has estimated more than 280 million of human infections each year; however, intraepithelial giardiasis is a rare entity, there are only 5 reports showing invasive giardiasis. A pediatric female patient with chronic abdominal pain, diarrhea, or pasty stools, without fever, was seen in the Gastroenterology and Nutrition Service. The stool studies were negative for pathogens and lactose hydrogen breath test was positive. The presumptive clinical diagnosis was giardiasis and the patient was empirically treated with nitazoxanide. But, the patient persisted with abdominal pain and pasty stools. Endoscopy was indicated to search for Helicobacter and Giardia. Guardian and patient gave written informed consent. Hematological profile was normal. The endoscopy was performed under general anesthesia and the biopsies and duodenal aspirate were obtained. The microscopic analyses of duodenal fluid showed Giardia trophozoites. Electron microscopic analysis was negative for Helicobacter pylori, but Giardia trophozoites with a typical crescent shape within the tissue were found. The patient was treated with tinidazole, subsequent tests showed that lactose absorption was normal, stool examinations were negative for Giardia and abdominal pain had stopped. This case suggest that intraepithelial giardiasis could be a common entity but unseen because the giardiasis diagnosis is usually made on fecal samples. Future studies are necessary to determine the role of intraepithelial trophozoites in giardiasis pathogenic mechanisms.

Toxocara canis is a nematode that parasitizes dogs, while humans are paratenic hosts. When humans are infected the migrating larvae damage the liver, lungs and even the nervous system. Larva migrans diagnosis is based on immunological techniques; however, the commercial immunodiagnostic kits detect anti-T. canis antibodies which may cross-react with other parasites, mainly nematodes with extra-intestinal migration. Moreover, antibodies do not necessarily reflect an active infection; so detection and quantification of circulating antigens may provide appropriate and timely information for treatment, which prevents irreversible damage. Here we report the standardization of a monoclonal antibody based antigen capture ELISA to diagnose human toxocariasis without cross-reaction. We developed anti-T. canis polyclonal antibodies in rabbits and a monoclonal antibody in mouse which did not cross-react with 15 antigens from several parasites. The sandwich ELISA standardization was performed using sera from mice experimentally infected. We tested the method using 29 positive and 58 negative human sera previously typified with a commercial kit, which detects antibodies. Only 5.0 μg/mL and 10 μg/mL polyclonal antibodies and monoclonal antibody, respectively, were needed in the sandwich ELISA standardization, detecting since 440 pg/mL larva antigens. Nine out of 29 antibody-positive sera were also positive for antigens and no false positive were found. Taking the antibody kit as the reference standard, the sensibility and specificity of the antigen test were 31% and 100%, respectively. With these tools we established a detection threshold as low as 440 pg/mL antigen. Monoclonal antibody is specific, and did not cross-react with antigens from other parasites. Detection of circulating antigens helps provide appropriate and timely treatment and prevents irreversible damage.