Dr. Murai Éva - Gubányi András szerk.: Parasitologia Hungarica 31. (Budapest, 1998)

Partial purification of protoscolex antigens and their possible role in the immunodiagnosis of echinococcosis Gul AHMAD

1 and Wajih Ahmad NlZAMI

2 Section of Parasitology, Department of Zoology Aligarh Muslim University, Aligarh - 202 002 India (Received 11 December, 1996) Abstract: Soluble proteins of the protoscoleces isolated from the hydatid cysts of the lung of Indian water buffalo were partially purified on a Sephadex G-200 column. Six major fractions (F1-F6) were tested for their antigenicity. The cell-mediated immune response (CMI) of dogs against these fractions was monitored by the migration inhibition test (MIT). Marked inhibition of macrophage migration was observed by using the Fl and F6 fractions only between 4 to 32 and 8 to 24 days post infection (PI), respectively. The circulating IgG response was also monitored by dot blotting using alkaline phosphatase conjugated anti-dog IgG. Considerable IgG response against fractions Fl, F2 and F6 was found from PI day 4, becoming more intensive with the age of infection. It is suggested that MIT can be used for detecting prépaient infections with E. granulosus in the dog by using the Fl (Mr > 90 kD) fraction of the protoscoleces as an antigen. Keywords: Echinococcus granulosus, prepatent period, dog, protoscolex, antigenic fractions, immune response, monocyte, macrophage, circulating IgG INTRODUCTION The diagnosis of canine echinococcosis is generally based on conventional microscopic coprological examination, which is time consuming and depends on maturity of the worms. Different strains of worms are known to have prepatent periods of varying length ranging from days 35 to 54 (McManus and Smyth 1986; Irshadullah and Nizami 1992). Therefore, early diagnosis of the infection is difficult, and thus immunological methods may be of practical utility. A number of antigens of immunodiagnostic potential have been reported from protoscoleces (Gasser et al. 1991,1992). Although recombinant antigens (like GST fusion protein 10P1) have also been tested for their diagnostic value, they showed relatively low sensitivity (Gasser et al. 1990). In the present study partially purified protoscolex antigens were used to monitor the immune response of dogs during the early development of the parasite in the definitive host, by the migration inhibition technique (MIT) for cell-mediated immunity (CMI) and by the dot blot assay for circulating antibodies.