Comparative study on rapid dot-immunogold staining and two immunogold silver staining assays for diagnosing schistosomiasis japonica.

A fast, specific, sensitive, convenient, and economical rapid-dot-immunogold staining (R-Dot-IGS) assay was used to detect serum antibodies in patients infected with Schistosoma japonicum. The soluble egg antigen of Schistosoma japonicum was added onto microspore membrane. After pre-reacting and blocking, the serum to be detected and sheep anti-human IgG labeled with chloroauric acid were added sequentially. The assay took 15 minutes. For comparison, the dot-immunogold silver staining (Dot-IGSS) and rapid micro-volume Dot-IGSS (RM-Dot-IGSS) assay were also performed. The positive rate to detect the serum of schistosomiasis japonica by the R-Dot-IGS, Dot-IGSS and RM-Dot-IGSS assay was 98%, 98% and 100%, respectively. Samples from 50 healthy controls, 10 cases of clonorchiasis, and 10 cases of paragonimiasis showed negative reactions except for one case of clonorchiasis with RM-Dot-IGSS assay. Compared with Dot-IGSS and RM-Dot-IGSS, R-Dot-IGS assay has similar sensitivity and specificity, but the latter is quicker, simpler, and cheaper. Therefore, R-Dot-IGS is strongly recommended for rapid diagnosis of schistosomiasis japonica both in epidemiological study and in the clinic.

Immunoblot analysis of Schistosoma japonicum egg antigens with sera from patients with acute and chronic schistosomiasis japonica.

Humoral immune responses of IgG, IgM, IgA, IgE and IgG subclass antibodies to Schistosoma japonicum egg antigens were determined by immunoblotting with serum samples from individuals in China with acute (n=24) or chronic (n=35) schistosomiasis. In general, IgM, IgA, and IgE in sera from acute patients exhibited strong binding to antigens but binding was much weaker in chronic cases. Reaction of IgG4 of chronic cases was stronger than that of IgG4 of acute cases. The recognition profile of each antibody isotype in sera was analyzed for 11 major antigen molecules (antigens with apparent molecular weights of 82, 76, 61, 57, 53, 46, 40, 32, 27, 10 and less than 6.5 kDa). Except for the 10 kDa molecule, they were well-recognized by IgA and IgE in sera of acute cases. In other combinations of antibody class and clinical phase, recognition patterns against these molecules differed among individuals. Notably, the 10 kDa molecule was specifically recognized by total IgG and IgG4 in sera from most of the chronic patients, but in sera from only one acute case. This result suggests that the 10 kDa molecule is one of the major target antigens of IgG4 and may be useful as a marker antigen to characterize the clinical phases of S. japonicum infection.

Human antibody isotype responses to Schistosoma japonicum egg antigen.

Schistosoma japonicum-infected subjects from Hubei province of China were investigated to determine the class and subclass of the antibody response to soluble egg antigen (SEA), using an enzyme-linked immunosorbent assay. The subjects were 50 acute and 55 chronic cases. In acute cases, the mean OD values for IgA, IgE and IgG3 were very high, while the positive ratios of IgA and IgE were only 78% and 74%, respectively. The positive ratios of IgG, IgM, IgG1, IgG3 and IgG4 were all above 90%. In chronic cases, the mean OD values for IgG, IgG3 and IgG4 were very high, and the positivity rates of IgG, IgG1, IgG3 and IgG4 were all above 90%. Comparing the two study groups, the mean OD values of IgM, IgA, IgE were higher in acute cases than those of chronic cases (p < 0.0001), while the mean OD values of IgG, IgG4 were higher in chronic cases than in acute cases (p < 0.05). The mean OD values of IgG3 in both groups were high and those of IgG2 in both groups were low.

Experimental studies on early treatment of schistosomal infection with artemether.

An early treatment with artemether given in appropriate regimens was tested in mice, rabbits and dogs for prevention purposes. Artemether was administered intragastrically (ig) to the hosts on day 7 after infection with Schistosoma japonicum cercariae at a single dose, and the same dose of artemether was repeated every 1 or 2 weeks for 2-4 times. As a result, most of the female worms were killed before their oviposition with female worm reduction rates of 90-100%, resulting in protection of the host from damage induced by schistosome eggs. When rabbits were treated ig with artemether 10 mg kg-1 on day 7 after infection, followed by repeated dosing every week for 4 times, some parameters related to acute schistosomiasis, such as temperature, eosinophil count and eggs in the feces were negative, and low specific antigen and antibody levels in serum were seen. Further study showed that the appropriate regimens of Artemether were also effective in early treatment of reinfection with cercariae. When rabbits infected with 48-52 cercariae once every other day for 5 times were treated ig with artemether 15 mg kg-1, followed by repeated dosing every 1 or 2 week for 2- 3 times, the female worm reduction rates were 92.1-98.4%. Histopathological examination of the livers showed that the above-mentioned early treatment with Artemether exhibited a promising protective effect on dogs and rabbits. The major features included normal appearance of the liver resembling those of uninfected dogs and rabbits; few or no dispersed miliary egg tubercles appeared on the surface of the liver; the structure of the hepatic lobules was normal with normal arrangement of the liver bundles; few or no eggs appeared in the portal vein area and there was apparent diminution of total egg granuloma, comprising inflammatory, fibrous or scarred egg granuloma. On the basis of above-mentioned results, early treatment with Artemether could be recommended for field trial for controlling acute schistosomiasis, reducing infection rate and intensity of infection.

Concentration time course of praziquantel in Filipinos with mild Schistosoma japonicum infection.

Despite extensive use of praziquantel, the current drug of choice for the treatment of schistosomiasis and other helminthic infections, little information is available about its pharmacokinetics in individuals living in geographic areas where such infections are endemic. We investigated the pharmacokinetics of praziquantel by determining its serum concentration-time course in four selected Filipino volunteers with mild Schistosoma japonicum infection who lived in an endemic area in the Southern Philippines. At specified intervals during a 24-hour time period after a single oral dose of praziquantel (25 mg/kg BW), intravenous samples of blood were drawn, processed and analyzed for praziquantel using reverse phase high pressure liquid chromatography. The same study was repeated one week later to assess pharmacokinetic reproducibility. A third study, simulating current field practice, consisted of dosing the patient four hours apart and analyzing for praziquantel in serial blood samples drawn at specified time intervals after the first and second dose. The following results were obtained: 1) Serum concentration-time course of praziquantel was reproducible for each patient but varied from patient to patient. 2) Praziquantel was rapidly absorbed in the gastrointestinal tract as measurable amounts appeared in the blood as early as 15 minutes after dosing. Time to peak serum concentration ranged from 1.50 to 6.00 hours with almost complete elimination from blood by 24 hours whether it was administered as a single dose (1 x 25 mg/kg BW) or as a twice a day dose (2 x 25 mg/kg BW) 4 hours apart. Half-life values ranged from 1.00 to 2.50 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Schistosoma japonicum: the modulation of lung granuloma and inhibition of egg maturation in mice by human sera.

Human sera taken from patients with chronic schistosomiasis japonica have been demonstrated to have two effects on mice. Sera from those patients reduced the size of granuloma in mice sensitised for accelerated granuloma formation to eggs entrapped in the lungs of mice injected with the sera shortly before and at day 2 after intravenous egg challenge. The sera with this effect on the mouse lung granuloma models caused large segmented precipitates in the optimised circumoval precipitin test (COPT). Such sera also reduced the rate at which eggs matured in the liver and intestines of mice infected with S. japonicum. The results strongly support our postulate that a major cause of granuloma modulation in cases of chronic schistosomiasis japonica is antiembryonation immunity and that mice provide useful models for the analysis of our postulate. Identification of egg antigens responsible for the anti-embryonation effect should facilitate progress towards the development of a vaccine against granulomatous disease.