Redescription of Pallisentis (Brevitritospinus) Indica (Acanthocephala: Quadrigyridae) from Channa punctatus Bloch & Schneider (Channidae) in Aligarh, India with New Understandings of Old Structures.

Pallisentis indica Mital and Lal, 1976 was originally described from Channa gachua Hamilton (Channidae) in Kali Nadi River, Aligarh, India. The parasite was later placed in the subgenus Brevitritospinus Amin, Heckmann, Ha, Luc, and Doanh, 2000 . Our collection from the spotted snakehead Channa punctatus Bloch & Schneider in another locality of the same stream in Aligarh produced many specimens with variable traits, revealing new structures that have never before been described in the Acanthocephala, especially relating to the ducted trunk spines. The proboscis has 4 circles of 10 hooks each, with hooks in the anterior 2 circles being considerably larger than those in the posterior 2 circles. Y-shaped trunk spines are ducted in 2 regions separated by a spineless zone. The anterior collar spines are in complete rings of 9-17 circles of crowded spines and the larger posterior trunk spines are in 1 (posterior) to 41 (anterior) circles extending to level of cement glands in males posteriorly. Considerable variations from the original description and new structures are reported for the first time.

Time-dependent tegumental surface changes in juvenile Fasciola gigantica in response to triclabendazole treatment in goat.

Triclabendazole (TCBZ), the anthelmintic drug active against both mature and immature liver flukes, was used to investigate the effect of in vivo treatment on the tegumental surface of juvenile Fasciola gigantica. Five goats were infected with 150 F. gigantica metacercariae each by oral gavage. Four of them were treated with single dose of TCBZ at 10mg/kg at four weeks post-infection. They were euthanized at 0 (untreated), 24, 48, 72 and 96h post treatment. Juvenile flukes were manually retrieved from the goat livers and processed for scanning electron microscopy. In control flukes, the anterior region was adorned with sharply pointed spines projecting away from the surface, while in the posterior region, spines become shorter and narrower, loosing serration and with the appearance of distinct furrows and papillae. The dorsal surface retained the same pattern of surface architecture similar to that of ventral surface. Flukes obtained from 24h post-treatment did not show any apparent change and were still very active. However, there were limited movements and some blebbing, swelling, deposition of tegumental secretions and some flattening displayed by the flukes of 48h post-treatment. All the worms were found dead 72h post-treatment and showed advanced level of tegumental disruptions, consisting of severe distortion of spines, sloughing off the tegument to expose the basal lamina, formation of pores and isolated patches of lesions. By 96h post-treatment, the disruption was extremely severe and the tegument was completely sheared off causing deeper lesions that exposed the underlying musculature. The disruption was more severe at posterior than anterior region and on ventral than dorsal surface. The present study further establishes the time-course of TCBZ action in vivo with 100% efficacy against the juvenile tropical liver fluke.

Cysteine protease is a major component in the excretory/secretory products of Euclinostomum heterostomum (Digenea: Clinostomidae).

Cysteine proteases of parasite organisms play numerous indispensable roles in tissue penetration, feeding, immunoevasion, virulence, egg hatching and metacercarial excystment. They are critical key enzymes in the biology of parasites and have been exploited as serodiagnostic markers, therapeutic and vaccine targets. In the present study, the cysteine proteases in the in vitro released excretory/secretory (E/S) products of the digenetic trematode parasite, Euclinostomum heterostomum have been analysed. The encysted progenetic metacercariae of E. heterostomum collected from the infected liver and kidney of Channa punctatus were excysted in vitro and incubated in phosphate buffer at 37 ± 1 °C, and the E/S products released were analysed. The spectrophotometric analysis of the proteases revealed active hydrolysis of chromogenic substrate, azocoll, in a time-, temperature- and pH-dependent manner. Optimum activity was observed at pH 7.0 at 37 ± 1 °C, and with 1 mM each of various protease inhibitors (Mini Protease Inhibitor Cocktail, ethylene diaminetetraacetic acid, phenyl methyl sulphonyl fluoride, iodoacetamide and 1,10-phenanthroline) used, significant inhibition was observed by iodoacetamide and 85% of inhibition at a concentration of 2 mM, suggesting that cysteine protease is a major component in the E/S of this parasite. Four discrete protease bands of Mr 36, 39, 43 and 47 kDa were identified by gelatin-substrate zymography. Maximum gelatinolytic activity was observed at pH 7.0, and among various inhibitors used, almost complete disappearance of protease bands was observed by 2 mM iodoacetamide. The proteolytic cleavage of bovine serum albumin, bovine haemoglobin and human haemoglobin in vitro were also studied.

Egg viability studies on Clinostomum complanatum (Digenea: Clinostomidae) from two experimental animal model systems.

Viability of eggs is important for the successful completion of trematode life cycle, both in natural and laboratory conditions. The present study was designed to check the viability of eggs released by the digenetic trematode parasite Clinostomum complanatum transformed in experimentally infected chicken and rabbit eye. The incubation of the released eggs in distilled water at 28 ± 1 °C led to the embryonation followed by hatching on tenth day to release miracidia. These can be used to infect the snails. We propose that these two in vivo model systems can be used as a source of viable eggs for further studies on developmental biology and life cycle where in law-protected animals are not to be used. To the best of our knowledge, in contrast to the previous attempts, this is the first successful study to report any experimental model to produce ovigerous adult worms capable of releasing viable eggs.

Incidence and histopathology of encysted progenetic metacercaria of Clinostomum complanatum (Digenea: Clinostomidae) in Channa punctatus and its development in experimental host.

OBJECTIVE: To study the incidence of encysted progenetic metacercariae of Clinostomum complanatum (C. complanatum) in Channa punctatus (C. punctatus), associated histopathology and the experimental infection to laboratory chicken to obtain ovigerous adult worms. METHODS: Live C. punctatus were brought from local fish market of Aligarh, India, dissected and examined on a monthly basis for the presence of C. complanatum cysts. For histochemistry, infected tissue sections with attached cysts were processed for haematoxylene and eosin staining. Cysts were aseptically fed to 4 day old leghorn chicken to obtain adult worms. Mechanically excysted metacercaria and the ovigerous adult worms were stained in carmine to prepare permanent slides. RESULTS: One year survey for the infection of encysted progenetic metacercaria of C. complanatum in C. punctatus revealed the prevalence, intensity and abundance of 24.7%, 2.27 and 0.608, respectively. Histopathology showed heavy infiltration of immune cells at the site of cyst attachment and some tissue damage was also evident. Following feeding to experimental chicken, about 41.07% of the encysted metacercariae were able to excyst and migrate back to bucco-pharyngeal region where they tenaciously attached and fed on blood, and transformed into ovigerous adult worms from 62 hours onwards of post infection. CONCLUSIONS: The parasite is potentially pathogenic to the host, and the availability of a suitable intermediate host can be a contributing factor for the occurrence of C. complanatum metacercaria either in the excysted or encysted form, indicating loose host specificity and zoonotic potential.