Secretion of trials during gliding motility of Eimeria nieschulzi (Apicomplexa, Coccidia) sporozoites visualized by a monoclonal antibody and immuno-gold-silver enhancement.

Abstract

Surface proteins of sporozoites and merozoites of pathogenic Sporozoa (Plasmodium, Toxoplasma, Cryptosporidium, Eimeria) are increasing in interest as subjects of research and are promising candidates for vaccines against these parasites (Brothers etal. 1988; Heidrich 1986; Johnson etal. 1983; Luft et al. 1987; Whitmire et al. 1989). However, little is known about the biological significance of these surface proteins. Surface proteins are in close interaction with the host cell during the invasion of parasites, reflecting a close relationship between motility and invasion (King 1988; Russell 1983). Little is known about the synthesis of these surface components or their integration into the parasite's cell membrane. Sporozoites of E. nieschulzi were excysted and incubated on glass slides in a moist chamber at 37~ using Dulbecco's modified Eagle's medium (DMEM; Gibco). After 5, 10 and 15 min, sporozoites were fixed in saturated formalin vapor and air-dried. An incubation with the monoclonal antibody (mcab) 3C3 (Tomavo et al. 1989) directly coupled to 5 nm colloidal gold was followed by silver enhancement using AuroProbe LM (Janssen Pharmaceutica, Beerse, Belgium). After 5-30 min, revelation slides were examined by light microscopy using bright-field and phase contrast (Zeiss, Photomikroskop II). Sporozoites that were allowed to glide on the glass slide for 5-15 rain left behind trails of 20-60gm in length and 0.3-0.5 gm in width (Figs. 1-4). Also, the surface of the sporozoites re-