Isolation and analysis of surface antigens of filarial nematode Setaria digitata.

Surface antigens of adult filarial parasite S. digitata was isolated by employing techniques from manual dissection to treatment with detergents. Among the surface antigen preparations (SAPs), the activities of marker enzymes such as alkaline phosphatase, adenosine triphosphatase and 5' nucleotidase were higher with that isolated by triton X-100 technique (SAP2). On SDS-PAGE, the SAP2 has three major proteins with molecular weights 17, 29 and 36 KD which were consistent with the PBS soluble cuticular proteins (SAP1). Besides these, few other minor protein bands were also observed with the other SAPs. All SAPs were antigenic and showed positive reaction against antiserum to SAP2, and the results confirmed the SAP2 as a better preparation. The release of 29 KD surface protein during in vitro culture of adult parasite and its cross-reactivity with antiserum to surface antigens revealed the possible natural shedding of surface molecules into the host system.