Cystic echinococcosis (CE), also called hydatidosis, is a zoonotic parasitosis worldwide distributed 1 caused by the larval stage (metacestode) of Echinococcus granulosus sensu lato. This hermaphrodite worm develops in the intestine of domestic and wild canids, and then its gravid proglottid releases the eggs to the faeces, contaminating the environment. The eggs ingested by the intermediate host hatch in the duodenum, and the oncosphere then penetrates the intestinal wall, migrates, and becomes trapped in the host's organs, where it becomes metacestode. The parasite's cycle is accomplished when the infected organ from the intermediate host is ingested by the definitive host (canids). 2 Humans, as intermediate accidental hosts, who are more exposed to the infection in unsanitary conditions, develop a parasitic disease involving the encystment of the larvae in different organs (the liver in 70%-80% of the cases, the lungs in 20%-30% of the cases and other organs with lower frequency), 3 resulting in a wide spectrum of clinical manifestations. Mitochondrial DNA has so far allowed identifying eight Echinococcus granulosus sensu lato genotypes (G1, G3-G8, and G10). 4,5 Four of these genotypes, G1 in sheep, G5 in cattle, G6 in camelids and G7 in swine, have been detected in Argentina. 4 Abstract Cystic echinococcosis (CE) can be diagnosed by means of several serological approaches, but their results vary among laboratories due to the molecular characteristics of the reference antigens used. Thus, this study aimed to address both the relevance of an EGPE cell line previously obtained from Echinococcus granulosus protoscoleces G1 and the complexity of the immune response by using two different in vitro growth stages as separate sources of parasite antigens. The serum reactivity was investigated by western blotting (WB) in 21 CE patients from an endemic area in a matched case-control design and also in seven experimentally infected sheep and five healthy control sheep. EGPE-antigen-human serum sensitivity by WB was higher than that of hydatid fluid (HF) WB, ELISA and DD5 (P < .05, Chi-square test). EGPE protein extract was immunogenic in mice and hyperimmune plasma reacted with HF proteins, and AgB2 expression was detected by molecular analysis. Proteins of 37 to 60 kDa were recognized by 95.24% of the CE patients' sera but, with poor specificity. Statistically significant differences were found between serum protein extract recognition at 7 and 20 days of cell growth. The EGPE cell line is a laboratory source of antigens for improvement of CE serological diagnosis. K E Y W O R D S cell line extract, Cystic echinococcosis, human, immunoblot, parasite, sera, sheep
