Immunolocalization and immunodetection of the excretory/secretory (ES) antigens of Fasciola gigantica

Abstract

The digenetic trematode Fasciola gigantica is a parasite of great agricultural and economic importance. Along with Fasciola hepatica, F. gigantica incurs huge economic losses to the agricultural sector. Because of unavailability of an effective and commercial vaccine, the earliest diagnosis of the disease is the only way to control the disease. The conventional coprological techniques are able to detect the disease only after the parasites get matured and starts releasing their eggs with the faeces of host, therefore prepatent infection remain undiagnosed. The alternative method is by serological tests that uses circulatory antigens. Despite high sensitivity, their reliability is quite low because of the common antigens shared between different helminth parasites. To overcome this, investigation was shifted to identify the copro-antigens which could be more sensitive and reliable. In the present study, we tried to identify some of the immunodominant proteins from the Excretory Secretory (ES) product of F. gigantica which can be further characterized and used for early detection of infection and also as drug and vaccine candidates. The ES products of F. gigantica were collected and used for raising the polyclonal antibody in rabbit. The polypeptide profile was generated as well as immunogenic polypeptides were identified. The Source of ES antigen was immunolocalized using confocal microscopy and dot blot assay was performed to diagnose field infection. The polypeptide profile of ES products revealed a total of 24 polypeptides out of which 12 immunogenic polypeptides were identified by western blotting. Confocal micrographs showed the immunolocalization of antigens in the intestinal caecae, vitalline glands, gonads as well as in the tegument of the worm. The dot blot assay confirmed the utility of ES products for the detection of field infection. Subsequently, cross reactivity was found negative with Gigantocotyle explanatum; an amphitome parasite of same habitat. However, the cross reactivity with other helminths needs to be worked out.

Immune response in goats vaccinated with thiol‐binding proteins from Haemonchus contortus

“…These data suggest that the antigens used in the immunizations are excreted/secreted by the parasite, so that the reactions observed within the worms would be the result of the recognition of precursors or proteins that would be part of those E/S products. The internal immunolocalization by anti‐E/S serum has also been observed in other helminths, such as Fasciola gigantica , in which the recognition of antigens in the gut and reproductive organs has also been reported . Our results could also explain the similarity of proteolytic profiles in gelatine gels of extracts obtained from H. contortus adult worm homogenates and those from their E/S products …”

The pervasive effects of recombinant Fasciola gigantica Ras-related protein Rab10 on the functions of goat peripheral blood mononuclear cells

“…Several studies have investigated various excretory/secretory products (ESPs) and virulence effector molecules employed by F. gigantica flukes to ensure their survival and establishment of persistent infection [ 5 , 6 ]. Rab proteins are a family of small GTP-binding proteins, part of the Ras superfamily, which regulate intracellular membrane trafficking of several pathogens; including parasites (e.g.…”

Immunodiagnosis of cattle fascioliasis using a 27 kDa Fasciola gigantica antigen

“…Serological tests for antibodies have limited diagnostic value as well because antibody titers persist after the infected cattle have been cured. In addition, the infected cattle with recent infections had a negative test; a phenomenon demonstrated in experimental animals during the first 1-4 weeks of infection [18][19][20].…”