Purification and characterization of a protective antigen from Eimeria tenella

Abstract

Chickens were partially protected against coccidiosis induced by Eimeria tenella by using extracts prepared from sonicated sporulated oocysts or from sonicated sporozoites. Following gel filtration of either extract, most of the protective antigens were confined to a single pool of proteins in the molecular mass range between 20 and 30 kDa. Further purification of proteins from the protective pool of sporulated oocyst extract yielded a protective polypeptide with a molecular mass of 26 kDa. An antiserum raised to this pool identified a polypeptide with a molecular mass of 22 kDa in the protective pool from a similarly prepared extract of sporozoites of E. tenella. In subsequent studies, this antiserum was used as an aid in cloning protective polypeptides.

Protective Immunity Induced by an Eimeria tenella Whole Sporozoite Vaccine Elicits Specific B-Cell Antigens

“…The antibody titers from rabbits increased at 14 days PI, peaked at 28 days, and then declined slightly to reach a plateau. This is consistent with previous reports where antibodies persist for prolonged periods in birds and rabbits that have received continuous booster doses [ 7 , 10 , 44 , 45 ]. The pattern of the antibody response indicates a maturation affinity event.…”

“…Yun et al [ 18 ] stated that some killed parasites administered as vaccines by different routes failed to induce protective immunity. Nonetheless, numerous studies have been carried out worldwide using soluble proteins from the sporozoite of E. tenella as a vaccine, and this type of immunogen has induced immune protection between 30% and 70% against homologous E. tenella challenge [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. To our knowledge, there are no previous reports on the use of the whole inactivated sporozoites as a vaccine in homologous challenge trials.…”

“…Vaccines with fractioned proteins of the E. tenella sporozoite have been used to test immunoprotection in challenge trials. Almost all of them have been shown to decrease the oocyst shedding of birds significantly [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. The sporozoite stage plays a critical role in invasion and likely represents the most amenable target for the host immune response, since in immune birds, they undergo a very restricted development or even fail to penetrate cells in the intestinal tract [ 8 , 13 , 14 ].…”

Life cycle stages, specific organelles and invasion mechanisms ofEimeriaspecies

“…Twenty years later a monoclonal antibody (1209-C2) specific for RBs (and able to bind related E. tenella proteins) was used to show that the merged RB separates into globules that diffuse through the schizont and re-concentrate as a refractile 'dot' within each first-generation merozoite (Danforth & Augustine, 1989). The protein target of the 1209-C2 was identified independently by two research groups seeking to validate vaccine antigens for control of coccidiosis (Crane et al, 1991;Miller et al, 1989). This RB protein, termed variously GX3262, 'B' antigen and SO7, contain large numbers of repetitive amino acid tracts (Liberator et al, 1989;Reid et al, 2014) and induce partial protection against challenge with up to four different species of Eimeria (Bhogal et al, 1989;Karkhanis et al, 1991).…”

“…The protein target of the 1209-C2 was identified independently by two research groups seeking to validate vaccine antigens for control of coccidiosis (Miller et al ., 1989; Crane et al ., 1991). This RB protein, termed variously GX3262, ‘B’ antigen and SO7, contain large numbers of repetitive amino acid tracts (Liberator et al ., 1989; Reid et al ., 2014) and induce partial protection against challenge with up to four different species of Eimeria (Bhogal et al ., 1989; Karkhanis et al ., 1991). SO7 (most common name) has been used as a candidate antigen in a variety of vaccinology studies (Song et al ., 2015; Yang et al ., 2017) although the mechanism of immune protection, and the biological function of this family of RB proteins, that are unique to the genus, remain unknown.…”