Diagnostic efficacy of monoclonal antibody based sandwich enzyme linked immunosorbent assay (ELISA) for detection of Fasciola gigantica excretory/secretory antigens in both serum and stool.

BACKGROUND: This research was carried out to develop a reliable monoclonal antibody (MoAb)-based sandwich enzyme linked immunosorbent assay (ELISA) for the diagnosis of active Fasciola gigantica infection in both serum and stool for comparative purposes. METHODS: From a panel of MoAbs raised against F. gigantica excretory/secretory antigens (ES Ags), a pair (12B/11D/3F and 10A/9D/10G) was chosen due to its high reactivity and strict specificity to F. gigantica antigen by indirect ELISA. RESULTS: The two MoAbs were of the IgG1 and IgG(2a) subclasses, respectively. Using SDS-PAGE and EITB, the selected MoAbs recognized 83, 64, 45 and 26 kDa bands of ES Ags. The lower detection limit of ELISA assay was 3 ng/ml. In stool, the sensitivity, specificity and diagnostic efficacy of ELISA was 96%, 98.2 and 97.1%; while in serum they were 94%, 94.6% and 94.3%, respectively. Moreover, a positive correlation was found between ova count in stool of F. gigantica infected patients and the OD readings of ELISA in both stool and serum samples (r = 0.730, p < 0.01 and r = 0.608; p < 0.01, respectively). CONCLUSIONS: These data showed that the use of MoAb-based sandwich ELISA for the detection of F. gigantica coproantigens in stool specimens was superior to serum samples; it provides a highly efficient, non-invasive technique for the diagnosis of active F. gigantica infection.

Immunological and parasitological parameters after treatment with dexamethasone in murine Schistosoma mansoni.

This work aimed to evaluate the effect of diphenyl dimethyl bicarboxylate (DDB) and dexamethasone alone and in combination with praziquantel on various parasitological, immunological and pathological parameters reflecting disease severity and morbidity in murine schistosomiasis. DDB and dexamethasone had no effect on worm burden but altered tissue egg distribution. This indicates that, under the schedule used, neither drug interfered with the development of adult worms or oviposition, but both can modulate liver pathology. Dexamethasone resulted in a greater reduction in granuloma size than did DDB. Dexamethasone-treated mice also showed lower levels of serum gamma interferon (IFN-γ), interleukin-12 (IL-12) and IL-4, together with higher IL-10 levels, than infected untreated control animals. These data suggest that dexamethasone is a convenient and promising coadjuvant agent that results in decreased morbidity in murine schistosomiasis.

Immunomodulation of pulmonary and hepatic granulomatous response in mice immunized with purified lung-stage schistosomulae antigen.

The present objective was to investigate the possible effect of immunization protocol against Schistosoma mansoni infection using purified lung-stage schistosomulae antigen. Two experimental models (lung & liver) were used, each of 3 groups (Gs): Immunized G. (10 mice) infected control G. (10 mice) and normal control G. (10 mice). Hundred microg of purified schistosomulae antigen followed by two booster doses each of 50 microg antigen and at one week interval were injected intraperitoneally into Swiss albino mice three days prior to intravenous injection of 3000 viable S. mansoni eggs (lung model) or to exposure to 100 cercariae (hepatic model). Mice were sacrificed 16 days post-injection (lung model) and 8 weeks post-infection (hepatic model). Various parasitological parameters, histopathological assessments and immunological parameters were studied. The data revealed that immunization with purified lung-stage schistosomulae antigen induces protective effect against S. mansoni infection. The marked reduction in worm burden, egg load, granuloma diameter and collagen content were accompanied by increased percentage of degenerated ova and amelioration of the associated pathological changes in pulmonary and hepatic tissue. Increased levels of specific immunoglobulins particularly IgG & IgM and decreased ratio of T cell subsets (CD4+/CD8+) in granulomas of both models were also noticed.