Haemonchus contortus is an economically important gastrointestinal parasite that infects primarily sheep and goats. To survive inside the host, the parasite must overcome the host immune response. In this study, we have identified and characterized a complement-C3-binding protein (H.c-C3BP) from this parasite employing biochemical and molecular biology tools. Initially, a truncated form of the protein was isolated from the excretory-secretory products of the parasite using C3-Sepharose column that facilitated its identification by mass spectroscopy. Subsequently, the parent molecule was generated in E. coli, and sequence analysis confirmed it as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). GAPDH reacted with the antiserum raised against the truncated protein, and the truncated protein reacted with anti-GAPDH antiserum. The protein inhibited complement function as measured by haemolytic assay and membrane attack complex (MAC) formation. Sera from H. contortus-infected animals reacted with GAPDH as well as the truncated form of the protein, which further lend support to protein secretion. Thus, the C3-binding property of H. contortus GAPDH is a new function, and it represents a new entity of complement-binding protein. Identification and characterization of H.c-C3BP should facilitate development of new therapeutics considering a key role of this protein in immune modulation.

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The present study is related to Dipylidium caninum infection in dogs. Three dogs about 1 year of age with the history of scooting behaviour and passing diarrhoeic stool containing white specks were presented before the clinicians. Physical examination of dogs revealed flea infestation and faecal examination revealed the presence of gravid segments, which were confirmed microscopically to be of cestode, D. caninum. Dogs were treated with Praziquantel@5 mg/kg body wt. orally. Dogs showed marked recovery post treatment. On re-examination after a week, faeces were found negative for any parasitic eggs/gravid segments.

In an attempt to develop a suitable serological test for early detection of Fasciola gigantica infection in buffaloes, a group of proteins were isolated from the somatic antigen of the parasite by immunoaffinity chromatography. The process of isolation of the proteins has been standardized and significant level of repeatability was achieved. To test the diagnostic potentiality of the antigens, two serological tests, viz., enzyme-linked immunosorbent assay (ELISA) and dot enzyme-linked immunosorbent assay, were standardized using the sera from experimentally noninfected (group A) and infected (group B) animals. Further, the sensitivity and the specificity of the tests were evaluated employing the field sera from animals of different parasitic load viz., F. gigantica positive (group C), F. gigantica and Gastrothylax crumenifer positive (group D), F. gigantica and Gigantocotyle explanatum positive (group E), a group of sera without F. gigantica but other trematode infection (group F), only G. crumenifer positive (group G), only G. explanatum positive (group H), G. crumenifer and G. explanatum positive (group I), and PM negative (group J) collected from slaughterhouses of Bareilly (Uttar Pradesh, India) and Patna (Bihar, India). In plate ELISA, the sensitivity of the antigen and the test was 75.75% while the specificity was 97%, 95%, and 98%, respectively, against G. crumenifer, G. explanatum, and mixed infection of G. crumenifer and G. explanatum, respectively. In the case of dot ELISA the sensitivity was 86.5% and specificity was 92.3%, 94.7%, and 90%, respectively, against G. crumenifer, G. explanatum, and mixed infection of G. crumenifer and G. explanatum, respectively. The potentiality of the antigen in the diagnosis of field infection is discussed.

Fasciola gigantica, causative agent of tropical fasciolosis, inflicts substantial economic losses on the livestock industry, affecting severely buffalo productivity in the tropical countries. Very few vaccination trials with different target antigens against F. gigantica infection have been conducted in this host. Present study describes a vaccination trial in buffaloes with F. gigantica recombinant glutathione S-transferase and fatty acid binding protein. The two recombinant proteins were expressed in Escherichia coli and evaluated for their immunoprophylactic potential in buffalo calves, using montanide 70 M-VG, a mineral oil-based adjuvant, for delivering the antigens. Buffalo calves were distributed in three groups, with group I, II and III calves immunized with recombinant glutathione S-transferase, fatty acid binding protein and a cocktail of these two antigens, respectively. Immunization of the calves evoked a mixed IgG1 and IgG2 antibody response. Present vaccination trial in these animals achieved a maximum protection level of 35%, when the two antigens were used in combination. Eosinophils were measured in both immunized and non-immunized challenge control animals, which showed a steady increase in their count in response to immunization with both the antigens and infection with F. gigantica, respectively.