Hymenolepis diminuta: Praziquantel removal of adult tapeworms is followed by apoptotic down-regulation of mucosal mastocytosis

The rat tapeworm, Hymenolepis diminuta, induces mastocytosis, hypertrophy of enteric smooth muscle, alteration of enteric myoelectric activity, and slowed enteric transit of the rat host's intestine. This report examines the resolution of both tapeworm-induced mastocytosis and tissue changes during the period following removal of the tapeworm with Praziquantel (PZQ). The dynamics of the mucosal mast cell (MMC) population following removal of the tapeworms was assessed by histochemical identification of MMC and morphometric techniques. As a possible mechanism of MMC population regulation, MMC apoptosis was examined over the same experimental period using the in situ nick end labeling of fragmented DNA (TUNEL). Shifts in MMC numbers were correlated with functional and morphological changes of the intestine following removal of the adult-stage tapeworm. Ileal tissues from rats infected 32 days with H. diminuta (the beginning of plateau phase of tapeworm-induced chronic mastocytosis) were harvested 1, 2, 3, and 4 weeks after the PZQ treatment. Control ilea were obtained either from rats which were never infected and never treated with PZQ or from rats infected with H, diminuta for 32 days but not treated with PZQ. In order to detect MMC and apoptosis, tissue sections of ileum were doubled stained sequentially with Astra blue for MMC granules followed by a modification of the TUNEL technique. No alteration in MMC numbers were observed in PZQ-treated animals until 3 weeks after the removal of the tapeworms. The decline of MMC occurred in the mucosa and submucosa. MMC numbers first approached uninfected control levels at 4 weeks posttreatment. Coincident with the decline in mucosal MMC numbers, the rate of MMC entering apoptosis also declined. Simultaneously, ileal smooth muscle layers, hypertrophied by infection, and mucosal structures began the process of involution and atrophy. Apoptosis of MMC in the submucosa and muscularis mucosa was not detected. In conclusion, H. diminuta elicited mastocytosis and increased thickness of both mucosa and muscularis externa do not begin a decline toward control Values until 3 weeks after the parasites are gone and normal intestinal motility is restored. These data are consistent with the lack of MMC mediation of altered motility, and the decline in the rate of MMC apoptosis at 3 weeks post-PZQ suggests that apoptosis may play an important role in the involution of tapeworm-induced mastocytosis. (C) 1999 Academic Press.

The occurrence of Crepidobothrium sp. (Cestoda, Proteocephalidae) in Bothrops moojeni (Hoge) (Serpentes, Viperidae)

The occurrence of Crepidobothrium sp.(Cestoda, Proteocephalidae) in the intestine of Bothrops moojeni (Hoge,1965)(Serpentes, Viperidae) is reported. The host snake was rescued from the fauna in Porto Primavera dam, Mato Grosso do Sul State, Brazil. The snake died in captivity on July 13,1999. At necropsy, 28 tapeworms were found in the snake intestine. The analysis of specimens morphology allowed the conclusion that they belong to the Crepidobothrium (Monticelli, 1900) genus. It was not possible to determine the Crepidobothrium species due to the lack of the gravid proglottids. This is the first report of B. moojeni as a host of cestodes.

Characterization of S3Pvac Anti-Cysticercosis Vaccine Components: Implications for the Development of an Anti-Cestodiasis Vaccine

Background: Cysticercosis and hydatidosis seriously affect human health and are responsible for considerable economic loss in animal husbandry in non-developed and developed countries. S3Pvac and EG95 are the only field trial-tested vaccine candidates against cysticercosis and hydatidosis, respectively. S3Pvac is composed of three peptides (KETc1, GK1 and KETc12), originally identified in a Taenia crassiceps cDNA library. S3Pvac synthetically and recombinantly expressed is effective against experimentally and naturally acquired cysticercosis.Methodology/ Principal Findings: In this study, the homologous sequences of two of the S3Pvac peptides, GK1 and KETc1, were identified and further characterized in Taenia crassiceps WFU, Taenia solium, Taenia saginata, Echinococcus granulosus and Echinococcus multilocularis. Comparisons of the nucleotide and amino acid sequences coding for KETc1 and GK1 revealed significant homologies in these species. The predicted secondary structure of GK1 is almost identical between the species, while some differences were observed in the C terminal region of KETc1 according to 3D modeling. A KETc1 variant with a deletion of three C-terminal amino acids protected to the same extent against experimental murine cysticercosis as the entire peptide. on the contrary, immunization with the truncated GK1 failed to induce protection. Immunolocalization studies revealed the non stage-specificity of the two S3Pvac epitopes and their persistence in the larval tegument of all species and in Taenia adult tapeworms.Conclusions/ Significance: These results indicate that GK1 and KETc1 may be considered candidates to be included in the formulation of a multivalent and multistage vaccine against these cestodiases because of their enhancing effects on other available vaccine candidates.