Immune-reaction of African and Chinese schistosomiasis patient sera in line-blots with recombinant Sj22

Ursula HERTER¹, Binta SAN¹, Ewald BECK² and Andreas RUPPEL^1
1 Department of Tropical Hygiene, University of Heidelberg
² Institute of Biochemisty, Academic Hospital Center; University of Giessen, Germany

A tegument-associated protein of 22 kD is expressed on Schistosoma mansoni larvae and adult worms. We have cloned this molecule from a S. japonicum cDNA library as recombinant His-tag-protein (rSj22) and purified it to near homogeneity. To be tested as potentially serodiagnostic antigen, rSj22 was dissolved in appropriate buffer and applied to nitrocellulose in a manner analogous to writing with ink on paper. We termed this novel technique as "line blot" (Beck, unpublished). The nitrocellulose strips are then ready to be processed in a way analogous to western blots with some modifications. We tested sera from schistosomiasis patients infected with S. mansoni (N =120 from Mali) or S. haematobium (n = 20 from Nigeria). All of these patients had a chronic infection. Over 95% of these African sera gave a positive result in Sj22- line blot. Patients with S. japonicum (n = 60 from the Hubei Province) were classified as acute, chronic or late stage schistosomiasis. The vast majority of chronic cases gave a positive reaction. However, among acute and late cases a substantial part of sera did not react. All healthy control sera were negative. Positive reactions with Sj22-line-blot were also obtained with sera from mice obtained 6 weeks after infection with 150 - 200 cercariae, but not with naive mice. We conclude: (i) rSj22 is valuable for diagnosis of infections with all human schistosomes; (ii) with S. japonicum, a differential response is observed with different stages of the disease.

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created 21/12/00