ANTIBODY-RESPONSES AGAINST EM18 AND EM16 SERODIAGNOSTIC MARKERS IN ALVEOLAR AND CYSTIC ECHINOCOCCOSIS PATIENTS FROM NORTHWEST CHINA

Western blot analysis was carried out in order to evaluate new serodia gnostic markers, Em18 and Em16, for differentiation of alveolar echino coccosis (AE) from cystic echinococcosis (CE) using 36 serum samples f rom hydatid patients from Xinjiang, China, where AE and CE are both en demic and one double infection case has been reported. All AE cases ex cept one (5/6) who exhibited a calcified lesion and a single case of d ouble infection showed antibody responses against Em18 and Em16. Some of CE patient sera (6/22) showed antibody response against Em16 except one who showed that against Em18. Analyses of IgG subclass responses against Em18 and Em16 were carried out using all serum samples showing antibody responses against Em18 and/or Em16 (seven CE, five AE, and o ne AE + CE) and additional samples of three CE and 22 AE from Sichuan, China. IgG(4) was the most predominant antibody subclass. Em18 and Em 16 were recognized by both IgG(4) and IgG(1) (in most cases) or by eit her IgG(4) or IgG(1) (in minor cases) or by IgG(3) (in very rare cases ). Neither Em18 nor Em16 was recognized by IgG(2) antibodies. The usef ulness of Em18 and Em16 as potential new markers for serological diffe rentiation of human AE and CE, respectively, is discussed.