The use of monoclonal antibody for the immunodiagnosis of Fasciola gigantica infection in cattle.

Antigens that were specific to Fasciola gigantica were obtained from the whole worm homogenate of the parasite by immunoaffinity chromatography in cyanogen bromide-activated sepharose 4B columns and used for the production of monoclonal antibodies. The F. gigantica-specific monoclonal antibody was labelled with horseradish peroxidase and used for the detection of circulating antigen by the direct ELISA method in the sera of cattle experimentally infected with the parasite. Circulating antigens were detectable in the sera of the animals as from the third week after infection while negative absorbance values were obtained 2 weeks after the termination of the infection by chemotherapy with oxyclozanide. This immunodiagnostic method offers an attractive alternative as a supplement to the conventional coprological diagnosis of fasciolosis.

The isolation of Fasciola gigantica-specific antigens and their use in the serodiagnosis of fasciolosis in sheep by the detection of circulating antigens.

The 17kDa and 69kDa polypeptide antigens which are specific to Fasciola gigantica were excised from polyacrylamide gels and used for the immunization of rabbits to raise monospecific antisera against these polypeptides. These sera were labelled with horseradish peroxidase and used for the detection of circulating 17 kDa and 69 kDa antigens by a direct enzyme-linked immunosorbent assay in the sera of sheep that were experimentally or naturally infected with F. gigantica. The 17 kDa antigen was detected in the sera of infected sheep as early as 1 week after infection and, following chemotherapy with oxyclozanide, negative seroconversion occurred 2 weeks later. The 69 kDa antigen was detectable as from the fourth week of infection and its detection ceased 3 weeks after chemotherapy. The serodiagnosis of F. gigantica, based on the detection of the 17 kDa antigen in sheep sera, was more specific and sensitive than that based on the detection of the 69 kDa antigen.

The immune response of Trypanosoma gambiense-infected mice to Schistosoma whole worm antigens.

Heterologous humoral and cellular immune response to Schistosoma mansoni and S. bovis antigens were investigated in Tryponosoma gambiense-infected mice in order to understand the concurrent immune response to both parasites. Immune response as measured by the Indirect Haemagglutination Test (IHA), Spontaneous sheep red blood cell rosette formation with B-lymphocytes and the mean number of T-lymphocytes forming rosettes with AET-treated SRBC to the schistosome antigens, was significantly depressed in the trypanosome-infected mice. Furthermore, the timing of trypanosome infection and the inoculation of antigen was related to the degree of immunosuppression as animals which had trypanosome infection and the whole worm antigen of S. mansoni and S. bovis simultaneously had higher IHA titre than those which were inoculated with the antigens 10 days after the commencement of an infection. The results are discussed from the viewpoint of immunological control of schistosomiasis in areas where both diseases are endemic.

Detection of circulating Fasciola gigantica antigen in experimental and natural infections of sheep with fasciolosis.

Detection of circulating Fasciola gigantica antigen was performed in sera of sheep with experimental and natural F. gigantica infections using the direct enzyme-linked immunosorbent assay method. Sera from sheep with monoinfections of Schistosoma bovis, Dicrocoelium hospes and Paramphistomum microbothrium were included in the assay to ascertain specificity. Circulating F. gigantica antigen (CFA) was detected as early as 1 week after infection in the experimentally infected sheep. No detectable CFA was observed 2 weeks after chemotherapy. Positivity rates of 82.5%, 12.5%, 10% and 10% were found in sera with monospecific infections of F. gigantica, P. microbrothrium, D. hospes and S. bovis, respectively. Acid treatment of the sera did not enhance the sensitivity of the assay.

Time-course analysis of antibody response by EITB and ELISA before and after chemotherapy in sheep infected with Fasciola gigantica.

The time-course analysis of the antibody response to Fascicola gigantica infection in sheep was studied by enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immunoelectrotransfer blot (EITB). Sera from sheep experimentally infected with F. gigantica were reacted with excretory-secretory antigens of the worm before and after chemotherapy with oxyclozanide. In ELISA, there was a significant increase in anti-Fasciola antibody by 2 weeks after infection and there was a sharp decrease in antibody titer by 4 weeks after treatment. By EITB, the infected sheep sera recognised four polypeptides in the range of 43-75 kDa as early as 2 weeks after infection, with more polypeptides being recognised as the infection progressed. Recognition of an 87 kDa antigen was lost by 2 weeks after treatment and is therefore a good marker for treatment efficacy. Comparative immunoblotting with sheep anti-Paramphistomum, anti-Dicrocoelium and anti-Fasciola sera revealed that the 17 kDa, 21 kDa, 57 kDa and 69 kDa proteins are specific to fasciolosis and are good antigens for early and specific immunodiagnosis of F. gigantica infection in sheep.

Immunodiagnosis of fasciolosis in ruminants using a 28-kDa cysteine protease of Fasciola gigantica adult worms.

A homogeneous extract of a 28-kDa cysteine protease of Fasciola gigantica adult worms was used as the antigen for immunodiagnosis of fasciolosis in cattle, sheep and goats using the Falcon assay screening test enzyme-linked immunosorbent assay technique. This antiprotease assay technique was found to be very rapid and sensitive and may be useful as a supplementary method for the diagnosis of fasciolosis in ruminants.