ELSEVIER zyxwvutsrq PARASITOLOGY zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Serologic Recognition of Hydatid Cyst Antigens Using Different Purification M ethods Younes Sbihi, Dirk Janssen, and Antonio Osuna zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONM The specificity and sensitivity of enzyme-linked immunosor- bent assays (ELlSA) and Western immunoblot assays in de- tecting antibodies in serum from patients sufiering cystic ky- datid disease (Echinococcus granulosus) are compared using either crude antigen preparations (total sheep kydatid fluid and homogenates of protoscoleces), purified fractions enriched in Antigens 5 and B, and glycoproteins from kydatid fklid. Polyprotein bands of 12-14, 20, and 34 kDa, when purified from kydatid fluid by applying changes in the ionic strength, yielded a sensitive (95% ) immunodiagnostic test that was also INTRODUCTION Today, the morphologic diagnosis of hydatidosis (Echinococcus grunulosus) is feasible by means of im- age techniques (digital radiography, ultrasonogra- phy, computerized tomography, and nuclear mag- netic resonance> and gives essential information on the location of cysts. However, clinical diagnosis is based only on assumption and needs specific confir- mation, for example by immunodiagnosis, to differ- entiate hydatidosis from other cystic lesions or tu- mors (Hira et al., 1993; Babba et al., 1994). The presence of raised specific antibody titers in patients with hydatid disease has been assayed by various techniques such as indirect hemagglutination or la- tex agglutination, immunoelectrophoresis, comple- ment fixation, and indirect fluorescent antibody tests From the Instituto de Biotecnologia, Universidad de Granada, Granada, Spain. Address reprint requests to Antonio Osuna, Instituto de Bio- tecnologia, Universidad de Granada, Campus Fuentenueva s/ n, 18071 Granada, Spain. Received 20 November 1995; revised and accepted 11 March 1996. DIAGN MICROBIOL INFECT DIS 1996;24:205-211 0 1996 Y. Sbihi et al. 655 Avenue of the Americas, New York, NY 10010 extremely specific (100% ) when assayed with sera from nonin- fected humans and from patients suffering from other parasitic diseases. However, subjecting kydatid fluid to chromatography through a concanavitin A column rendered a 42 kDa band that was sensitive (95% ) as well as kigkZy specific (100%) for kydatidosis. Therefore, purification procedures can strongly affect the diagnostic value zyxwvutsrqponmlkjihgfedcbaZYXWVU of antigens with identical electro- pkoretic bekavior in sodium dodecyl sulfate-polyacylamide gel electropkoresis (SDS-PAGE). (Rickard and Lightowlers, 1985). In addition, en- zyme-linked immunosorbent assay (ELISA) is con- sidered an effective method overall to evaluate the serological immunostatus of patients (Farag et al., 1975). However, the literature on this subject often contains apparently contradictory reports concern- ing the specificity and sensitivity of the assay, sug- gesting that its effectiveness depends largely on the type of antigen source used, and making compari- sons difficult (Shepherd and McManus, 1987; Light- owlers et al., 1989; Siracusano et al., 1991). Western blotting of hydatid antigens followed by ELISA has confirmed the importance of defined di- agnostic antigens such as antigens 5 and B (Shepherd and McManus, 1987). In the present report, we com- pare the sensitivity and specificity of ELISA using different preparations of hydatid antigen, and, by means of immunoblotting, we describe the diagnos- tic value of the antigen composition according to the way the antigen was prepared. Different polypep- tides that are present in protoscoleces and in hydatid fluid were purified from the latter following the tra- ditional method used to obtain a preparation en- riched in antigens 5 and B (Oriol et al., 1971), and 0732-8893/ 96 PII SO732-8893(96)00061-2