Development of the rapid and simple elisa (whole blood-ELISA) using coconut water-tween as a wash solution for whole blood sample from Schistosoma japonicum-infected rabbit and human.

PBS-Tween as a wash solution, prepared with distilled water, is used in ELISA. In areas where schistosomiasis is endemic, however, distilled water is hard to come by. We have modified a WHOLE BLOOD-ELISA test to use coconut water-Tween as a wash solution, because coconut water is easy to come by and cheap in the tropics. We applied the test to whole blood samples from rabbits and humans infected with Schistosoma japonicum. This modified WHOLE BLOOD-ELISA was confirmed to be a rapid, simple, and cost-effective method.

A rapid and simplified ELISA using whole blood samples of Schistosoma japonicum-infected rabbits.

A rapid and simplified ELISA using whole blood samples of Schistosoma japonicum-infected rabbits was compared with a conventional ELISA. This whole-blood ELISA has advantages. The volume of crude egg antigens, whole blood samples, and conjugates was only 0.05 ml. The incubation time was shortened to 5 minutes. Wells were washed three to five times with PBS-Tween after each procedure. Optical density values were measured in 10 minutes after transfer of 0.1 ml of substrate. Constant temperature was not necessary. The entire procedure took only 20-30 minutes.

Development of the rapid and simplified ELISA (WHOLE BLOOD-ELISA) using samples of Schistosoma japonicum-infected human whole blood.

An ELISA technique was developed using samples of Schistosoma japonicum-infected human whole blood based on the conventional ELISA. In this study, the following were demonstrated. 1) Whole blood samples could be used. 2) The volume of whole blood and conjugate could be reduced to 0.05 ml. 3) The incubation time was shortened to 5 minutes. 4) The optical density could be measured at 10 minutes after transferring the substrate and the volume was reduced to 0.1 ml. 5) It did not require a fixed temperature setting. 6) The operation time was as short as 20 to 30 minutes. 7) The optical density values were almost the same as the conventional ELISA and were not influenced by other common intestinal helminthic infections. 8) The observed variations from day to day including effects of sampling in stool examination were negated by the results of this ELISA technique. 9) Based on correlation with stool examination results, criteria can be formulated in which optical density values of 0.3 and above as positive, 0.1 to less than 0.3 as doubtful, and less than 0.1 as negative. Whenever an immunological field survey is necessary, before and after a selective or a mass treatment control program, this WHOLE BLOOD-ELISA, which was shown to be rapid and simple, is recommended.

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.